JP3885936B2 - Polarization control circuit array and optical circuit using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polarization control circuit array that enables polarization independence of optical components, and a polarization-independent optical circuit using the polarization control circuit array. Examples of the optical circuit include an optical amplifier array, an optical modulator array, an optical switch array, and an optical attenuator array for controlling the optical intensity of light having a plurality of wavelengths. The present invention is useful when applied to optical components constituting an optical wavelength division multiplexing communication system.
[0002]
[Prior art]
In order to respond to the demand for an increase in capacity of a communication system accompanying the explosive progress of the Internet, optical wavelength division multiplexing is widely used. Various optical components such as an optical switch array and an optical attenuator array for controlling the light intensity for each of a plurality of wavelengths are indispensable for configuring an optical wavelength division multiplexing communication system.
[0003]
However, in high-speed transmission, an effect caused by polarization, such as polarization dependent loss (PDL) of an optical component, causes degradation of the quality of the optical signal, which is a problem. For example, in a Mach-Zehnder interferometer (MZI) type LN modulator that performs light intensity modulation using the electro-optic effect, the electro-optic effect has a very large polarization dependency, and thus usually a large PDL is generated. .
[0004]
This PDL becomes a serious problem when the MZI type LN modulator is used as an optical attenuator or an optical switch.
[0005]
Therefore, in order to eliminate PDL, conventionally, there is a method of demultiplexing light into two orthogonal polarizations, converting the demultiplexed light into the same polarization (TM polarization), and then performing individual modulation. Proposed (for example, G.Isikawa et al., ECOC96, Th3-3, Oslo “80-Gb / s (2x40-GB-s) transmission experiments over 667-km dispersion-shifted fiber using Ti: LiNbO3 OTDM modulator and demultiplexer ").
[0006]
FIG. 12 shows a schematic configuration example of a polarization-independent optical modulator using this technique. In FIG. 12, 1201a-1201b is an input optical waveguide, 1202 and 1216a-1216b are polarization multiplexing / demultiplexing circuits, 1204 and 1214 are ordinary half-wave plates, and 1206a-1206b and 1212a-1212b are directivity Couplers, 1208a-1208c are ground electrodes, 1209a-1209b are signal electrodes, and 1217a-1217b are output optical waveguides. Reference numerals 1203a-1203b, 1205a-1205b, 1207a-1207d, 1210a-1210d, 1213a-1213d, and 1215a-1215d denote optical waveguides.
[0007]
The polarization multiplexing / demultiplexing circuit 1202 and the half-wave plate 1204 constitute a first polarization control circuit. The half-wave plate 1204 is inserted in the groove between the optical waveguides 1203a and 1205a connected to the upper output port of the polarization multiplexing / demultiplexing circuit 1202, as indicated by the blackened portion. The polarization multiplexing / demultiplexing circuit 1202 demultiplexes the input arbitrarily polarized light into TM polarization and TE polarization. The half-wave plate 1204 converts TE polarized light out of the demultiplexed light into TM polarized light. As a result, the input light is demultiplexed into two orthogonal polarizations, and the demultiplexed light is converted into the same polarization (TM polarization).
[0008]
A directional coupler 1206a, a directional coupler 1212a, an upper arm (optical waveguides 1207a and 1210a) and a lower arm (optical waveguides 1207b and 1210b) therebetween, and a signal electrode 1209a provided on the lower arm are MZI. A type LN modulator is configured. Similarly, a directional coupler 1206b, a directional coupler 1212b, an upper arm (optical waveguides 1207c and 1210c) and a lower arm (optical waveguides 1207d and 1210d) therebetween, and a signal electrode 1209b provided on the upper arm are also provided. And MZI type LN modulator. These two upper and lower MZI LN modulators both receive TM-polarized light and control the light intensity according to the electrical signals applied to the respective signal electrodes 1209a and 1209b.
[0009]
The half-wave plate 1214 and the polarization multiplexing / demultiplexing circuits 1216a and 1216b constitute a second polarization control circuit. The half-wave plate 1214 is indicated by a blackened portion, as shown in each groove of two adjacent optical waveguides (grooves between the optical waveguides 1213c and 1215c connected to the through ports of the lower MZI type LN modulator, Inserted in the groove between the optical waveguides 1213d and 1215d connected to the cross port), the TM polarized light output from the through port and the cross port of the lower MZI LN modulator is TE polarized. Convert to The polarization multiplexing / demultiplexing circuit 1216a outputs TM polarized light output from the through port of the upper MZI type LN modulator, and is output from the through port of the lower MZI type LN modulator, and has a 1/2 wavelength. The plate 1214 combines the light polarized from the TM polarization to the TE polarization. Similarly, the polarization multiplexing / demultiplexing circuit 1216b outputs the TM polarized light output from the cross port of the upper MZI LN modulator and the cross port of the lower MZI LN modulator. The two-wave plate 1214 combines the light converted from the TM polarization into the TE polarization.
[0010]
Details of the operation are as follows.
(1) The light input from the input optical waveguide 1201a or 1201b is demultiplexed into TE polarization and TM polarization by the polarization multiplexing / demultiplexing circuit 1202. The demultiplexed TE-polarized light is converted into TM-polarized light by the half-wave plate 1204 through the optical waveguide 1203a, and then output to the upper MZI LN modulator through the optical waveguide 1205a. The demultiplexed TM polarized light passes through the optical waveguides 1203b and 1205b and is output to the lower MZI type LN modulator as it is.
(2) The TM polarized light output from the through port of the upper MZI LN modulator is input to the polarization multiplexing / demultiplexing circuit 1216a as it is through the optical waveguides 1213a and 1215a. The TM polarized light output from the through port of the lower MZI LN modulator is converted to TE polarized light by the half-wave plate 1214 through the optical waveguide 1213c, and then polarized through the optical waveguide 1215c. The signal is input to the branching circuit 1216a. The polarization multiplexing / demultiplexing circuit 1216a combines the input TM polarization and TE polarization and outputs the resultant to the output optical waveguide 1217a.
(3) Similarly, the TM polarized light output from the cross port of the upper MZI LN modulator is input to the polarization multiplexing / demultiplexing circuit 1216b through the optical waveguides 1213b and 1215b. The TM polarized light output from the cross port of the lower MZI type LN modulator is converted to TE polarized light by the half-wave plate 1214 through the optical waveguide 1213d, and then polarized through the optical waveguide 1215d. The signal is input to the branching circuit 1216b. The polarization multiplexing / demultiplexing circuit 1216b multiplexes the input TM polarization and TE polarization, and outputs them to the output optical waveguide 1217b.
[0011]
As described above, in the conventional polarization-independent optical modulator, it is possible to set all the polarizations to polarizations having a large electro-optic effect, and the electro-optic effect can be used efficiently. At the same time, since polarization independence is possible, it is very effective as an optical modulator.
[0012]
By the way, in optical wavelength division multiplexing communication, an optical intensity controller such as an optical switch or an optical attenuator is required for each wavelength. Therefore, for example, a quadruple polarization-independent optical modulator array as shown in FIG. 13 can be manufactured by using the polarization-independent optical modulator shown in FIG.
[0013]
13, 1301a to 1301d are input optical waveguides, 1302 and 1316 are polarization multiplexing / demultiplexing circuits (ellipse marks), 1304 and 1314 are ordinary half-wave plates, and 1306 and 1313 are directional couplers. (Triangular mark), 1308 is a ground electrode, 1309 is a signal electrode, 1317a-1317h is an output optical waveguide, and 1318 is a crossed waveguide (circle mark). For simplicity, other optical waveguide symbols are omitted.
[0014]
In FIG. 13, since there are four polarization-independent optical modulator arrays, the first polarization control circuit array has four, four polarization multiplexing / demultiplexing circuits 1302 and one 1 / It consists of a two-wave plate 1304. The MZI-type LN modulator array has 8 stations, and includes 8 directional couplers 1306, 16 arm waveguides, and 8 directional couplers 1313. The second polarization control circuit array is a quadruple, and includes eight polarization multiplexing / demultiplexing circuits 1316 and one half-wave plate 1314.
[0015]
The half-wave plate 1304 constituting the first polarization control circuit array is a normal one inserted into a plurality of adjacent (four in this example) optical waveguides as indicated by the blackened portion. It is. In order to insert such a half-wave plate 1304 into only a desired optical waveguide, the first polarization control circuit array can be used by complicating many optical waveguides and using six crossed waveguides 1318. Four polarization multiplexing / demultiplexing circuits 1302 and eight directional couplers 1306 are connected.
[0016]
Similarly, the half-wave plate 1314 constituting the second polarization control circuit array is also inserted into a plurality of (four in this example) adjacent optical waveguides as indicated by the blackened portion. It is normal. Therefore, in order to insert the half-wave plate 1314 only in a desired optical waveguide, the second polarization control circuit array can be configured to draw many optical waveguides in a complicated manner and use 28 crossed waveguides 1318. Eight directional couplers 1312 and eight polarization multiplexing / demultiplexing circuits 1316 are connected.
[0017]
[Problems to be solved by the invention]
However, as shown in FIG. 13, it is necessary to insert normal half-wave plates 1304 and 1314 only in a desired optical waveguide.
(1) It is necessary to route a complicated optical waveguide, which increases the circuit size.
(2) The crossed waveguide 1318 is necessary, which causes an increase in excess loss.
(3) Since the number of crossing waveguides 1318 differs depending on the path through which light passes, the crossing loss (excess loss due to the crossing waveguide) depends on the optical path.
[0018]
The dependence of the crossing loss on the optical path will be specifically described with reference to FIG. The circuit configuration of FIG. 14 is exactly the same as FIG. Here, two paths A and B from the uppermost polarization multiplexing / demultiplexing circuit 1302 of the first polarization control circuit array to the uppermost polarization multiplexing / demultiplexing circuit 1316 of the second polarization control circuit array. think of. The path A is an optical path passing through the uppermost MZI LN modulator, and the path B is an optical path passing through the fifth MZI LN modulator from the top. Also, for example, LiNbO on the substrate _Three When a Ti diffusion optical waveguide is used as the Z-cut optical waveguide and the crossing angle is 40 degrees, a crossing loss of 0.2 dB is generated per crossing angle.
[0019]
Therefore, the crossing loss of the path A is 0 dB because there is no crossing waveguide, and the crossing loss of the path B is 2.0 dB because there are 10 crossing waveguides 1318, and the excess path has an optical path dependency. In the case of this configuration, the difference of 2.0 dB in the cross loss due to the paths A and B becomes the PDL as it is, which causes a very problem.
[0020]
An object of the present invention is to realize a compact and low-loss polarization control circuit array that can reduce the complicated routing of optical waveguides and crossing waveguides, and to achieve a small and low-loss using this polarization control circuit array It is to realize a polarization-independent optical circuit.
[0021]
[Means for Solving the Problems]
A first invention is a polarization control circuit array that solves the above-described problem, and includes two or more polarization multiplexing / demultiplexing circuits and one or more comb-shaped half-wave plates, and the comb teeth The optical half-wave plate is inserted into either the input optical waveguide or the output optical waveguide of the polarization multiplexing / demultiplexing circuit at an angle of 45 degrees with respect to the substrate.
According to the first invention, it is possible to convert all input light into the same single polarization. In addition, the dependence of excess loss on the optical path can be reduced.
[0022]
A second invention is an optical circuit that solves the above-described problems, and is an optical circuit including a first polarization control circuit array, a second polarization control circuit array, and a polarization-dependent light intensity control circuit array. The first polarization control circuit array, the light intensity control circuit array, and the second polarization control circuit array are connected and arranged in order, and the first and second polarization control circuit arrays are arranged in order. The wave control circuit array is the polarization control circuit array of the first invention.
According to the second aspect of the present invention, it is possible to reduce the number of optical waveguides and crossed waveguides, and a small and low-loss polarization-independent optical circuit, such as a polarization-independent waveguide-type optical amplifier array, A wave-independent optical modulator array and a polarization-independent optical attenuator array can be realized. In addition, the dependence of excess loss on the optical path can be reduced.
[0023]
According to a third aspect of the present invention, there is provided an optical circuit for solving the above-described problems, comprising: a first polarization control circuit array; a second polarization control circuit array; and a polarization-dependent optical phase control circuit array. The first polarization control circuit array, the optical phase control circuit array, and the second polarization control circuit array are connected and arranged in order, and the first and second polarization control circuit arrays are arranged in order. The wave control circuit array is the polarization control circuit array of the third invention.
According to the third aspect of the present invention, it is possible to reduce the routing of the optical waveguides and the crossed waveguides, and the small and low loss polarization independent optical circuit, for example, the polarization independent optical switch array, the polarization independent light, etc. A modulator array and a polarization-independent optical attenuator array can be realized. In addition, the dependence of excess loss on the optical path can be reduced.
[0024]
4th invention is an optical circuit which solves the above-mentioned subject, and is provided with the 1st optical circuit group, the 2nd optical circuit group, and the 3rd optical circuit group which were connected and arranged in order, said 1st The optical circuit group includes a first optical coupling circuit array and a first polarization control circuit array connected in order, and the second optical circuit group includes the first optical circuit group. An optical phase control circuit array composed of the same number of input / output optical waveguides as the output optical waveguides connected to the output optical waveguides, and a phase shift circuit for changing the phase of the light loaded in the input / output optical waveguides In the third optical circuit group, a second polarization control circuit array and a second optical coupling circuit array are sequentially connected. The first and second polarization control circuits The array is the polarization control circuit array of the first invention.
According to the fourth aspect of the present invention, it is possible to reduce the routing of the optical waveguides and the crossed waveguides, and to achieve a small and low-loss polarization-independent optical circuit, such as a polarization-independent optical switch array or polarization-independent light. A modulator array and a polarization-independent optical attenuator array can be realized. In addition, the dependence of excess loss on the optical path can be reduced.
[0025]
A fifth invention is an optical circuit that solves the above-described problems, and includes a first optical circuit group, a second optical circuit group, and a third optical circuit group that are connected and arranged in order, and The optical circuit group includes a first polarization control circuit array and a first optical coupling circuit array connected in order, and the second optical circuit group includes the first optical circuit group. An optical phase control circuit array composed of the same number of input / output optical waveguides as the output optical waveguides connected to the output optical waveguides, and a phase shift circuit for changing the phase of the light loaded in the input / output optical waveguides The third optical circuit group is formed by sequentially connecting a second optical coupling circuit array and a second polarization control circuit array, and the first and second polarization control circuits. The array is the polarization control circuit array of the first invention.
According to the fifth aspect of the present invention, it is possible to reduce the routing of the optical waveguides and the crossed waveguides, and to reduce the size and low loss of the polarization-independent optical circuit, for example, the polarization-independent optical switch array, the polarization-independent light. A modulator array and a polarization-independent optical attenuator array can be realized. In addition, the dependence of excess loss on the optical path can be reduced.
[0026]
In a sixth aspect based on the fifth aspect, the number of polarization multiplexing / demultiplexing circuits constituting the first polarization control circuit array is greater than the number of optical coupling circuits constituting the first optical coupling circuit array. An optical circuit characterized in that the number of polarization multiplexing / demultiplexing circuits constituting the second polarization control circuit array is smaller than the number of optical coupling circuits constituting the second optical coupling circuit array. .
According to the sixth aspect of the invention, it is possible to reduce the number of optical waveguides and crossed waveguides, and to realize a small and low loss polarization-independent optical circuit. In addition, the circuit size can be further reduced. Furthermore, the optical path dependency of excess loss can be reduced.
[0027]
A seventh invention is an optical circuit according to the fourth invention, wherein a reflecting surface is provided on the output side of the second optical circuit group instead of the third optical circuit group.
According to the seventh aspect of the present invention, it is possible to reduce the number of optical waveguides and cross waveguides, and to realize a small-sized and low-loss polarization-independent optical circuit. Further, the circuit size can be further reduced, and highly efficient optical phase control can be performed. Furthermore, the optical path dependency of excess loss can be reduced.
[0028]
An eighth invention is an optical circuit according to the fifth or sixth invention, wherein a reflection surface is provided on the output side of the second optical circuit group instead of the third optical circuit group. is there.
According to the eighth aspect of the invention, it is possible to reduce the number of optical waveguides and crossed waveguides, and to realize a small-sized and low-loss polarization-independent optical circuit. Further, the circuit size can be further reduced, and highly efficient optical phase control can be performed. Furthermore, the optical path dependency of excess loss can be reduced.
[0029]
According to a ninth invention, in the fourth or seventh invention, the individual optical circuit groups are arranged on different substrates, the substrates are abutted at the end faces, and the optical waveguides between the optical circuit groups are optically coupled to each other. This is an optical circuit.
According to the ninth aspect of the invention, it is possible to reduce the number of optical waveguides and crossed waveguides, and to realize a small-sized and low-loss polarization-independent optical circuit. In addition, the yield of optical circuit fabrication is improved. Furthermore, the optical path dependency of excess loss can be reduced.
[0030]
According to a tenth aspect, in the fifth, sixth, or eighth aspect, the individual optical circuit groups are arranged on different substrates, the substrates are abutted at the end faces, and the optical waveguides between the optical circuit groups are optically connected to each other. An optical circuit characterized by being coupled.
According to the tenth aspect of the present invention, it is possible to reduce the number of optical waveguides and cross waveguides, and to realize a small and low loss polarization independent optical circuit. In addition, the yield of optical circuit fabrication is improved. Furthermore, the optical path dependency of excess loss can be reduced.
[0031]
Here, as the optical phase control circuit array, one using an electro-optic effect for phase control or one using a thermo-optic effect can be used. When using the electro-optic effect, it is preferable to use a material having a large electro-optic effect such as a lithium niobate-based optical waveguide as the optical waveguide. When the thermo-optic effect is used, it can be manufactured using various optical waveguides such as a quartz-based optical waveguide and a plastic-based optical waveguide as well as an optical waveguide having a large electro-optic effect.
In addition, when individual optical circuit groups are arranged on different substrates and connected to the end faces, the substrates may be of the same type or different types. When an optical circuit group including an optical coupling circuit array and a polarization control circuit array is manufactured by a silica-based optical waveguide formed on a silicon substrate, it is suitable for connection to an external optical fiber and has a comb-like shape 1/2 It is easy to form a groove for inserting a wave plate.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a polarization control circuit array of the present invention and an optical circuit using the same will be described with reference to the drawings.
[0033]
[First embodiment]
FIG. 1 shows a configuration of a polarization control circuit array as a first embodiment of the present invention. The polarization control circuit array according to the present embodiment has four stations, and is configured by using four polarization multiplexing / demultiplexing circuits 102a to 102d and one comb-shaped half-wave plate 103. The comb-shaped half-wave plate 103 is inserted into the output optical waveguides 104a, 104c, 104e, and 104g of the polarization multiplexing / demultiplexing circuits 102a to 102d with the main axis inclined at 45 degrees with respect to the optical waveguide.
[0034]
In this polarization control circuit array, a planar silicon substrate is used as the substrate on which the circuit is placed, and quartz optical waveguides such as the input optical waveguides 101a-101h and output optical waveguides 104a-104h are used as the optical waveguides necessary for the configuration of the polarization control circuit array. An optical waveguide is used.
[0035]
The eight output optical waveguides 104a-104h as well as the input optical waveguides 101a-101h do not cross and are not routed, as can be seen from FIG. In this example, as shown in the figure, these optical waveguides are all arranged linearly and parallel.
[0036]
Each of the four polarization multiplexing / demultiplexing circuits 102a-102d separates the light input from the input optical waveguides 101a-101h into TE polarization and TM polarization, and outputs them to the output optical waveguides 104a-104h.
[0037]
In this embodiment, the polarization multiplexing / demultiplexing circuit 102a outputs TE polarization to the output optical waveguide 104a and TM polarization to the output optical waveguide 104b, and the polarization multiplexing / demultiplexing circuit 102b outputs the TE polarization to the output optical waveguide 104c. TM polarization is output to the output optical waveguide 104d. The polarization multiplexing / demultiplexing circuit 102c outputs TE polarization to the output optical waveguide 104e and TM polarization to the output optical waveguide 104f. It is assumed that the circuit 102d outputs a TE polarized wave to the output optical waveguide 104g and a TM polarized wave to the output optical waveguide 104h.
[0038]
The half-wave plate 103 is different from a normal one in order to be inserted into a desired output optical waveguide because the eight output optical waveguides 104a to 104h do not intersect and are not drawn as described above. It is comb-like. Specifically, among the eight parallel output optical waveguides 104a-104h, the intervals and widths of the output optical waveguides 104a-104h are set so that they can be inserted into every other output optical waveguide 104a, 104c, 104e, 104g. Together, it is formed in a comb-teeth shape. Four black portions of the comb-like half-wave plate 103 are portions (tooth portions) inserted into the output optical waveguides 104a, 104c, 104e, and 104g.
[0039]
When inserting the comb-shaped half-wave plate 103, for the convenience of processing, grooves 8 that divide all eight output optical waveguides 104a-104h into a straight line are produced. A comb-shaped half-wave plate 103 is inserted in the portion corresponding to the output optical waveguides 104a, 104c, 104e, and 104g. FIG. 2 is an enlarged view of the insertion part of the comb-shaped half-wave plate 103. In FIG. 2, reference numeral 28 represents the optical principal axis of the comb-shaped half-wave plate.
[0040]
The comb-shaped half-wave plate 103 is mechanically inserted in the groove 1 perpendicular to the plane (substrate) on which the circuit is arranged, but optically the output optical waveguides 104a, 104c, 104e. , 104g, the optical principal axis 28 of the comb-like half-wave plate 103 is inserted with a 45-degree tilt. In general, since the optical waveguide is manufactured in parallel with the substrate plane, the comb-shaped half-wave plate 103 is inserted with the optical main axis 28 inclined by 45 degrees with respect to the substrate (plane).
[0041]
Here, the flow of the optical signal in the polarization control circuit array shown in FIG. 1 will be described. For example, light input to the input optical waveguide 101a enters the polarization multiplexing / demultiplexing circuit 102a and is separated into TE polarization and TM polarization. Since the comb-shaped half-wave plate 103 is inserted into the output optical waveguide 104a through which the TE polarized light propagates with the optical principal axis inclined by 45 degrees, the comb-shaped half-wave plate 103 transmits the light to the TE. Convert from polarization to TM polarization. Since the comb-shaped half-wave plate 103 is inserted into the output optical waveguide 104b through which TM polarized light propagates, the polarization of the light remains TM polarized. As a result, TM polarized light is emitted from the two output optical waveguides 104a and 104b. Similarly, when light is input to the input optical waveguide 101b, all TM polarized light is output from the two output optical waveguides 104c and 104d, and when light is input to the input optical waveguide 101c, the two output optical waveguides 104e and 104f are input. When TM polarized light is input to the input optical waveguide 101d, all TM polarized light is emitted from the two output optical waveguides 104g and 104h. Therefore, in the polarization control circuit array of this embodiment, all input light can be converted into the same polarization (TM polarization) and emitted.
[0042]
When the polarization control circuit array has the configuration shown in FIG. 1 using the comb-shaped half-wave plate 103, the following effects (1) and (2) are obtained.
(1) Crossing waveguides can be reduced.
(2) Complex routing of the optical waveguide can be eliminated.
[0043]
As a result, the following effects (1), (2) and (3) are obtained.
(1) Cross loss (excess loss due to crossed waveguide) can be reduced.
(2) It is possible to eliminate the optical path dependency of loss due to cross loss.
(3) Circuit size can be reduced
[0044]
In this embodiment, all input light is converted into TM polarized light. However, if the comb-like half-wave plate 103 is inserted into the output optical waveguides 104b, 104d, 104f, 104h, all input light is TE. It can be converted into polarized light and emitted.
[0045]
In this embodiment, a quadruple polarization control circuit array is described. However, the same effect as described above can be obtained even in a similar two or more polarization control circuit array.
[0046]
In this embodiment, one comb-shaped half-wave plate 103 is used, but two or more comb-shaped half-wave plates may be used side by side. In the method using a plurality of comb-shaped half-wave plates, the width of the comb-shaped half-wave plate becomes longer with one, such as when the polarization control circuit array is multiple and the number of output optical waveguides is large. This is useful when the number is too large, and it is preferable to arrange a plurality of comb-shaped half-wave plates in the dividing direction of the optical waveguide.
[0047]
Further, a portion of the groove 1 where the comb-like half-wave plate 103 is not inserted (outlined portion) is filled with an adhesive having a refractive index substantially equal to that of the optical waveguide in order to reduce loss. If the loss is small, the groove may remain open.
[0048]
Further, in this embodiment, the grooves 1 are all formed by dividing the output optical waveguides 104a-104h for easy processing, but the grooves are formed only in the optical waveguides into which the comb-shaped half-wave plates 103 are inserted. You may do it.
[0049]
[Second Embodiment]
FIG. 3 shows the configuration of a polarization-independent waveguide-type optical amplifier array as a second embodiment of the present invention. The waveguide type optical amplifier array of the present embodiment has four series, four series of polarization control circuit arrays (first polarization control circuit array) 2 and eight series of light intensity control circuit arrays (intensity modulation circuit arrays). ) 3 and 4 series of polarization control circuit arrays (second polarization control circuit array) 4. In this waveguide optical amplifier array, a planar silicon substrate is used as a substrate on which a circuit is arranged, and quartz is used as an optical waveguide necessary for the configuration of the polarization control circuit array such as the input optical waveguides 301a-301d and the output optical waveguides 307a-307d. System optical waveguide is used.
[0050]
This waveguide type optical amplifier array is configured by sequentially connecting and arranging a polarization control circuit array 2, a light intensity control circuit array 3, and a polarization control circuit array 4. In this embodiment, the polarization control circuit array 2, the light intensity control circuit array 3, and the polarization control circuit array 4 are individually fabricated on different substrates, and then fabricated on the same plane by PLC-PLC substrate connection. Yes.
[0051]
The polarization control circuit array 2 uses four polarization multiplexing / demultiplexing circuits 302a-302d and one comb-shaped half-wave plate 303, and outputs light from the four polarization multiplexing / demultiplexing circuits 302a-302d. A comb-like half-wave plate 303 is inserted into the waveguide with its optical principal axis inclined 45 degrees with respect to the substrate (optical waveguide), and is configured in the same manner as the polarization control circuit array shown in FIG. ing. That is, eight output optical waveguides 104a-104h of the four polarization multiplexing / demultiplexing circuits 102a-102d and polarization multiplexing / demultiplexing circuits 102a-102d in FIG. Reference numeral 103 denotes eight output optical waveguides of four polarization multiplexing / demultiplexing circuits 302a-302d, one comb-shaped half-wave plate 303, and polarization multiplexing / demultiplexing circuits 302a-302d in FIG. (Although there is no code, it corresponds to an optical waveguide connected to the input side of the light intensity control circuit array 3).
[0052]
In this example, the polarization control circuit array 2 demultiplexes all input arbitrary polarization light into two orthogonal polarizations (for example, TM polarization and TE polarization), and then the same polarization, for example, TM polarization. It shall be converted into a wave.
[0053]
The polarization control circuit array 4 is composed of one comb-shaped half-wave plate 305 and four polarization multiplexing / demultiplexing circuits 306a to 306d, and four comb-shaped half-wave plates 305 are provided. Are inserted into the input optical waveguides of the polarization multiplexing / demultiplexing circuits 302a to 302d with the optical principal axis inclined by 45 degrees with respect to the optical waveguides. In this polarization control circuit array 4, the arrangement order of the comb-shaped half-wave plate 305 and the polarization multiplexing / demultiplexing circuits 306a to 306d is reversed, but the polarization control circuit array 2 and the polarization shown in FIG. As with the wave control circuit array, not only the output optical waveguides 307a to 307d but also the eight input optical waveguides of the polarization multiplexing / demultiplexing circuits 306a to 306d (there is no code, but connected to the output side of the light intensity control circuit array 3) Optical waveguides) are not crossed and are not routed. Also in this embodiment, these optical waveguides are all arranged linearly and parallel. Details will be described later.
[0054]
The light intensity control circuit array 3 is a hybrid integration of the same number of input / output optical waveguides as the output optical waveguides of the polarization control circuit array 2 and the input optical waveguides of the polarization control circuit array 4, and an array element of a semiconductor optical amplifier (SOA). It is a thing. The semiconductor optical amplifier array element includes eight semiconductor optical amplifiers 304a to 304h, and each semiconductor optical amplifier is connected to each input / output optical waveguide.
[0055]
Each semiconductor optical amplifier of the light intensity control circuit array 3 controls the light intensity of the same polarization (TM polarization in this example) converted by the polarization control circuit array 2.
[0056]
FIG. 4 is an enlarged view of a PLC mounting substrate that is hybrid-integrated using two quadruple semiconductor optical amplifier array elements 5 and 6 as the light intensity control circuit array 3. In FIG. 4, two quadruple semiconductor optical amplifier array elements 5 and 6 are hybrid-mounted with high density using the Si terrace mounting portion 9 on which the AuSn solder patterns 7 and 8 for fixing are formed as a height reference. Optically coupled to the eight input optical waveguide cores 10 and the eight output optical waveguide cores 11 on both sides of the terrace mounting portion 9. Reference numerals 12 and 13 denote electrodes for driving the quadruple semiconductor optical amplifier array elements 5 and 6, respectively.
[0057]
Here, the polarization control circuit array 4 will be described in detail. The half-wave plate 305 has a comb-like shape, unlike a normal one, in order to be inserted into a desired optical waveguide among the eight input optical waveguides that do not intersect and are not routed. . Specifically, among the eight parallel input optical waveguides, it is formed in a comb-teeth shape according to the interval and width of the optical waveguides so that it can be inserted into every other optical waveguide. Four black portions of the comb-shaped half-wave plate 305 are portions (tooth portions) inserted into the input optical waveguide.
[0058]
When inserting the comb-shaped half-wave plate 305, for the convenience of processing, the grooves 14 that divide all the eight input optical waveguides into a straight line are produced, and every other light in the grooves 14 is formed. A comb-shaped half-wave plate 305 is inserted in a portion corresponding to the waveguide. This comb-shaped half-wave plate 305 is also mechanically inserted in the groove 14 perpendicular to the substrate, but optically inserted with the optical principal axis inclined by 45 degrees with respect to the optical waveguide. The In general, since the optical waveguide is made parallel to the substrate plane, the comb-shaped half-wave plate 305 is inserted with the optical principal axis inclined by 45 degrees with respect to the substrate.
[0059]
In the present embodiment, the comb-shaped half-wave plate 305 converts light output from the semiconductor optical amplifiers 304b, 304d, 304f, and 304h from TM polarization to TE polarization.
[0060]
The four polarization multiplexing / demultiplexing circuits 306a to 306d are respectively composed of TM polarized light output from the semiconductor optical amplifiers 304a, 304c, 304e, and 304g and TE polarized light (semiconductor optical amplifier) paired therewith. 304b, 304d, 304f, and 304h, and the light that is converted from TM polarized light to TE polarized light by comb-shaped half-wave plate 305) is combined and output to output optical waveguides 307a-307d To do.
[0061]
Here, the flow of the optical signal in the waveguide type optical amplifier array shown in FIG. 3 will be described. For example, light input to the input optical waveguide 301a enters the polarization multiplexing / demultiplexing circuit 302a, and is separated into TE polarization and TM polarization. Since the comb-shaped half-wave plate 303 is inserted in the optical waveguide through which the TE-polarized light propagates, the comb-shaped half-wave plate 303 converts the light from the TE polarized light to the TM polarized light. . Since the comb-shaped half-wave plate 303 is not inserted in the optical waveguide through which TM polarized light propagates, the polarization of the light remains TM polarized. As a result, TM polarized light is incident on the two semiconductor optical amplifiers 304a and 304b. By applying the same current to the two semiconductor optical amplifiers 304a and 304b, exactly the same amplification efficiency without polarization dependence is obtained. Is obtained. Then, one of the amplified lights is converted into TE polarized light by the comb-shaped half-wave plate 305, and is combined with the other TM polarized light that does not pass through the comb-shaped half-wave plate 305. The signal is synthesized by the wave circuit 306a. As a result, light amplified in a polarization-independent manner is obtained from the output optical waveguide 307a. Similarly, when light is input to the input optical waveguide 301b, it is output from the output optical waveguide 307b, when light is input to the input optical waveguide 301c, from the output optical waveguide 307c, and when light is input to the input optical waveguide 301d, the output optical waveguide is output. Light amplified in a polarization-independent manner is obtained from the waveguide 307d.
[0062]
In this way, the polarization control circuit array 2 is shown in FIG. 3 using the comb-like half-wave plate 303 and the polarization control circuit array 4 is shown in FIG. With the configuration, the following effects (1) to (5) are obtained.
(1) Crossing waveguides can be reduced.
(2) Complex routing of the optical waveguide can be eliminated.
(3) Cross loss (excess loss due to crossed waveguide) can be reduced.
(4) The dependence of the loss on the optical path due to the crossing loss can be eliminated.
(5) Circuit size can be reduced
[0063]
The effects of the entire waveguide type optical amplifier array include the following (1) to (4), which are very useful.
(1) Even if the amplification efficiency of the light intensity control circuit array 3 or the semiconductor optical amplifier array elements 5 and 6 has a large polarization dependence, the configuration using the polarization control circuit arrays 2 and 4 Independent optical amplification is possible.
(2) By using the polarization control circuit array 2 to convert all the input light into the polarized light having the best amplification efficiency of the light intensity control circuit array 3, high-efficiency optical amplification becomes possible.
(3) By separately producing the polarization control circuit array 2, the light intensity control circuit array 3, and the polarization control circuit array 4, a waveguide type optical amplifier array can be produced with a high yield.
(4) Depending on the amplification method, various polarization-independent light intensity controls such as light intensity increase, attenuation, and modulation can be realized.
[0064]
In this embodiment, a four-waveguide optical amplifier array is described. However, the same effect as described above can be obtained even in a similar two- or more-waveguide optical amplifier array.
[0065]
In this embodiment, after the polarization control circuit array 2, the light intensity control circuit array 3, and the polarization control circuit array 4 are individually manufactured, the substrates are end-face connected. Even if the polarization control circuit array 2, the light intensity control circuit array 3, and the polarization control circuit array 4 are all manufactured, the effect obtained by using the comb-shaped half-wave plates 303 and 305 can be similarly expected. In this case, the yield can be lowered, but there is an advantage that excess loss due to end face connection can be eliminated.
[0066]
Further, in the present embodiment, also in the polarization control circuit array 4, as in the polarization control circuit array 2, the portion of the groove 14 where the comb-shaped half-wave plate 305 is not inserted (outlined portion) In order to reduce the loss, it is filled with an adhesive having a refractive index almost equal to that of the optical waveguide. If the loss is small, the groove may remain open.
[0067]
Further, for the sake of simplicity of processing, the groove 14 is formed by dividing all the input optical waveguides, but the groove may be formed only in the optical waveguide into which the comb-shaped half-wave plate 305 is inserted.
[0068]
In this embodiment, the polarization control circuit array 4 is a quadruple array in which the comb-shaped half-wave plate 305 is inserted into the input optical waveguide. Can be configured.
[0069]
In this embodiment, one comb-like half-wave plate 305 is used for the polarization control circuit array 4, but two or more comb-like half-wave plates may be used side by side. In the method using a plurality of comb-shaped half-wave plates, the width of the comb-shaped half-wave plate is increased by one, such as when the polarization control circuit array is multiple and the number of input optical waveguides is large. This is useful when the number is too large, and it is preferable to arrange a plurality of comb-shaped half-wave plates in the dividing direction of the optical waveguide.
[0070]
Furthermore, in the present embodiment, the polarization control circuit array 2 converts all input light into TM polarization and emits it to the light intensity control circuit array 3. By shifting the position, all input light can be converted into TE polarized light and emitted to the light intensity control circuit array 3.
[0071]
Further, by shifting the insertion position of the comb-shaped half-wave plate 305 in the polarization control circuit array 4, the output light of the semiconductor amplifiers 304a, 304c, 304e, and 304g is converted from TM polarization to TE polarization. be able to.
[0072]
[Third embodiment]
FIG. 5 shows a configuration of a polarization-independent optical switch array as a third embodiment of the present invention. The optical switch array of this embodiment includes four directional coupling circuits (optical coupling circuits) 5A02, 5B02, 5A17, 5B17 and eight polarization multiplexing / demultiplexing circuits 5A05a, 5A05b, 5B05a, 5B05b, 5A14a, 5A14b. , 5B14a, 5B14b, two comb-shaped half-wave plates 507, 512, and eight optical phase control circuit arrays (details will be described later).
[0073]
In other words, the optical switch array of this embodiment includes a first optical coupling circuit array (5A02, 5B02), a first polarization control circuit array (5A05a, 5A05b, 5B05a, 5B05b, 507), and an optical phase control. 2 × 2 optical switch comprising a circuit array, a second polarization control circuit array (512, 5A14a, 5A14b, 5B14a, 5B14b) and a second optical coupling circuit array (5A17, 5B17) connected in sequence. Are two series of 2 × 2 optical switch arrays in which two are vertically aligned in parallel.
[0074]
In this example, LiNbO is formed on the substrate of the duplex 2 × 2 optical switch array. _Three Z-cut is used. Also, input optical waveguides 5A01a, 5A01b, 5B01a, 5B01b, output optical waveguides 5A18a, 5A18b, 5B18a, 5B18b, other optical waveguides 5A03a, 5A03b, 5B03a, 5B03b, 5A04a, 5A04b, 5B04a, 5B04b, 5A06, 5A04, 5A06 5A06d, 5B06a, 5B06b, 5B06c, 5B06d, 5A08a, 5A08b, 5A08c, 5A08d, 5B08a, 5B08b, 5B08c, 5B08d, 5A09a, 5A09b, 5A09c, 5A09d, 5B09a, 5B09b5,5c9 Ti diffusion optical waveguides are used as 5B13a, 5B13b, 5B13c, 5B13d, 5A15a, 5A15b, 5B15a, 5B15b, 5A16a, 5A16b, 5B16a, and 5B16b.
[0075]
The optical phase control circuit array of the present embodiment includes signal electrode wirings 5A11a, 5A11b, 5A11c, 5A11d, 5B11a, 5B11b, 5B11c, 5B11d and ground electrode wirings 5A10a, 5A10b, 5A10c, 5A10d, 5B10a, 5B10b, as phase shift circuits. 5B10c and 5B10d are loaded.
[0076]
The configuration of the optical phase control circuit array will be described with reference to FIG. FIG. 6 is a sectional view taken along line A1-A2 in FIG. 5 and shows a sectional structure of the optical phase control circuit array. That is, each optical waveguide 5A08a, 5A08b, 5A08c, 5A08d, 5B08a, 5B08b, 5B08c, 5B08d connecting the first polarization control circuit array and the second polarization control circuit array has a buffer layer interposed therebetween. It is loaded with signal electrodes 5A11a, 5A11b, 5A11c, 5A11d, 5B11a, 5B11b, 5B11c, and 5B11d that guide the electrical signals for phase control, and serve as an optical phase control circuit that performs phase control. Plays. The ground electrode wirings 5A10a, 5A10b, 5A10c, 5A10d, 5B10a, 5B10b, 5B10c, and 5B10d are loaded beside each signal electrode.
[0077]
The first polarization control circuit array includes polarization multiplexing / demultiplexing circuits 5A05a, 5A05b, 5B05a, between the four polarization multiplexing / demultiplexing circuits 5A05a, 5A05b, 5B05a, 5B05b and the optical phase control circuit array. By inserting a comb-like half-wave plate 507 into the output waveguide of 5B05b, the configuration is the same as that of the polarization control circuit array 2 shown in FIG. That is, the four polarization multiplexing / demultiplexing circuits 302a-302d in FIG. 3, the eight output optical waveguides of these polarization multiplexing / demultiplexing circuits 302a-302d, and one comb-shaped half-wave plate 303 are provided. Each of the four polarization multiplexing / demultiplexing circuits 5A05a, 5A05b, 5B05a, 5B05b in FIG. 5 and the eight output optical waveguides 5A06a, 5A06b, 5A06c, 5A06d, 5B06a, 5B06b, 5B06c of these polarization multiplexing / demultiplexing circuits. , 5B06d corresponds to one comb-shaped half-wave plate 507. The comb-shaped half-wave plate 507 is composed of four output optical waveguides 5A06a, 5A06b, 5A06c, 5A06d, 5B06a, 5B06b, 5B06c, and 5B06d of the polarization multiplexing / demultiplexing circuit. The optical main axis is inserted into the output optical waveguides 5A06b, 5A06d, 5B06b, and 5B06d with an inclination of 45 degrees with respect to the substrate.
[0078]
In the present embodiment, the first polarization control circuit array demultiplexes the input arbitrary polarization light into two orthogonal polarizations (for example, TM polarization and TE polarization), and then the same polarization, For example, it is assumed that conversion to TM polarization is performed.
[0079]
Further, the second polarization control circuit array includes a polarization multiplexing / demultiplexing circuit 5A14a, 5A14b, between the optical phase control circuit array and the four polarization multiplexing / demultiplexing circuits 5A14a, 5A14b, 5B14a, 5B14b. By inserting a comb-like half-wave plate 512 into the input waveguides 5B14a and 5B14b, the configuration is the same as that of the polarization control circuit array 4 shown in FIG. That is, the four polarization multiplexing / demultiplexing circuits 306a to 306d in FIG. 3, the eight input optical waveguides of the polarization multiplexing / demultiplexing circuits 306a to 306d, and one comb-shaped half-wave plate 305 are provided. Each of the four polarization multiplexing / demultiplexing circuits 5A14a, 5A14b, 5B14a, 5B14b in FIG. 5 and the eight input optical waveguides 5A13a, 5A13b, 5A13c, 5A13d, 5B13a, 5B13b, 5B13c of these polarization multiplexing / demultiplexing circuits. , 5B13d corresponds to one comb-shaped half-wave plate 512. The comb-shaped half-wave plate 512 has four inputs every other one of the eight input optical waveguides 5A13a, 5A13b, 5A13c, 5A13d, 5B13a, 5B13b, 5B13c, and 5B13d of the polarization multiplexing / demultiplexing circuit. The optical main axis is inserted into the optical waveguides 5A13a, 5A13c, 5B13a, and 5B13c with an inclination of 45 degrees with respect to the substrate.
[0080]
The second polarization control circuit array converts all TM polarizations that have not been converted by the first polarization control circuit array into TE polarizations.
[0081]
In both the first and second polarization control circuit arrays, since the comb-like half-wave plates 507 and 512 are used, the optical waveguides do not intersect and are not routed. All the optical waveguides are linearly arranged and parallel.
[0082]
Here, the flow of optical signals and the operation principle in the optical switch array shown in FIG. 5 will be described. For example, in the upper 2 × 2 optical switch, light input to the input optical waveguide 5A01a is equally distributed to the optical waveguides 5A03a and 5A03b by the directional coupling circuit 5A02, and reaches the optical waveguides 5A04a and 5A04b. Light propagating through the optical waveguides 5A04a and 5A04b is incident on the polarization multiplexing / demultiplexing circuits 5A05a and 5A05b, and is separated into TE polarization and TM polarization, respectively. The optical waveguide 5A06b, 5A06d through which the TE polarized light propagates is inserted with a comb-like half-wave plate 507 with the optical principal axis inclined 45 degrees to convert the TE polarized light into the TM polarized light. In the optical waveguides 5A08a-5A08d for performing phase control, TM polarization is propagated in all cases. Of these optical waveguides 5A13a-5A13d in which these TM polarized waves propagate from the optical waveguides 5A08a-5A08d through the optical waveguides 5A09a-5A09d, the optical waveguides 5A13a, 5A13c have a comb-teeth half wavelength with the optical main axis inclined by 45 degrees. A plate 512 is inserted to convert the propagating TM polarization into the TE polarization. Light that has passed through the comb-shaped half-wave plate 512 (TE polarization) and light that has not passed through (TM polarization that propagates through the optical waveguides 5A13b and 5A13d) are polarized by the polarization multiplexing / demultiplexing circuits 5A14a and 5A14b. The signals are combined and further combined by the directional coupling circuit 5A17. At this time, when a half-wavelength phase difference is given between the light guided through the optical waveguides 5A15a and 5A15b, the light propagates from the directional coupling circuit 5A17 to the output optical waveguide 5A18a. When no phase difference is given between the light guided through the optical waveguides 5A15a and 5A15b, the light propagates from the directional coupling circuit 5A17 to the output optical waveguide 5A18b. That is, an optical switch is realized by providing a desired phase difference with the optical phase control circuit array. The same applies when light is input to the input optical waveguide 5A01b and when light is input to the input optical waveguides 5B01a and 5B01b of the lower 2 × 2 optical switch.
[0083]
Next, a method for giving a phase difference in the optical phase control circuit array will be described with reference to FIG. In FIG. 6, + V is applied to the signal electrodes 5A11a and 5A11b above the optical waveguides 5A08a and 5A08b, and −V voltage is applied to the signal electrodes 5A11c and 5A11d above the optical waveguides 5A08c and 5A08d. At this time, an electric field is generated in the optical waveguide 5A08a-5A08d in the Z direction in the figure, and LiNbO _Three Due to the electro-optic effect of the optical waveguides 5A08a and 5A08c and the light propagated through the optical waveguides 5A08b and 5A08d, a phase difference is generated. This phase difference can be set to an arbitrary value by adjusting the applied voltage to make it a half-wavelength phase difference, no phase difference, or the like. The same applies when a voltage is applied to the signal electrodes 5B11a and 5B11b above the optical waveguides 5B08a and 5B08b and the signal electrodes 5B11c and 5B11d above the optical waveguides 5B08c and 5B08d.
[0084]
Next, a mechanism for making polarization independence will be described. LiNbO _Three The electro-optic effect in the Z-cut is greatly different between the TE polarized wave and the TM polarized wave. Therefore, the light is separated into TE polarization and TM polarization by a polarization multiplexing / demultiplexing circuit, and only TE polarization is converted to TM polarization using a half-wave plate, and all is converted to TM polarization. Keep it. Thereafter, desired phase control is performed individually for each TM polarization. As a result, only the same single polarized wave is individually modulated, and thus the polarization dependence does not occur in the modulated optical signal. Therefore, a polarization-independent optical switch can be obtained.
[0085]
Here, the effect of using the comb-shaped half-wave plate for the first and second polarization control circuit arrays will be described.
(1) When a polarization-independent optical switch array is configured using a conventional half-wave plate, it is necessary to combine the optical waveguide into which the half-wave plate is inserted and the optical waveguide into which the half-wave plate is not inserted. The optical waveguide is routed and a cross waveguide is essential. For example, the optical waveguide (LiNbO of this example) _Three When a crossed waveguide with a crossing angle of 40 degrees is produced using a Z-cut substrate and a Ti diffusion optical waveguide, an excess loss of 0.2 dB occurs per point (one crossing angle). The number of crossed waveguides increases as the number of arrays increases.
(2) However, by using the comb-like half-wave plates 507 and 512, the crossed waveguides can be reduced, and the increase in excess loss due to the crossed waveguides can be eliminated.
(3) Moreover, since the crossing waveguide due to the routing of the optical waveguide can be removed, the dependency of the crossing loss on the optical path can be eliminated.
(4) Furthermore, it is not necessary to route the optical waveguide, and the circuit size can be reduced. For example, in the duplex 2 × 2 optical switch array of this example, the circuit length can be reduced by about 1 mm as compared with the conventional configuration using a normal half-wave plate.
[0086]
As described above, the polarization-independent duplex 2 × 2 optical switch array of this embodiment has advantages such as very low loss because there is no crossing waveguide.
[0087]
In the present embodiment, the dual optical switch array has been described. However, the same effect can be obtained in a single optical switch having the same configuration or in an optical switch array having three or more optical switches.
[0088]
In this example, a lithium niobate-based optical waveguide is used as an optical waveguide having a large electro-optic effect. _1-x Nb _x O _Three Or K _1-y Li _y Ta _1-x Nb _x O _Three The same effect can be obtained even with optical waveguides using other multi-element oxide crystals such as.
[0089]
Furthermore, in this embodiment, the electro-optic effect is used to change the phase in the optical phase control circuit array. However, the phase can also be changed using the thermo-optic effect. In this case, an optical switch using the thermo-optic effect is realized by using a heater for applying heat to the optical waveguide and a wiring for supplying a current to the heater as the phase shift circuit. Such a thermo-optic optical switch also has polarization dependency. Therefore, by using a thermo-optic optical switch array having a configuration using a comb-like half-wave plate similar to that of the present embodiment, the same effect as described above can be obtained and useful. In the case of a thermo-optic type optical switch array, the optical waveguide is not limited to a lithium niobate-based optical waveguide, but a light having a thermo-optic effect such as a multi-component optical waveguide represented by quartz glass or a plastic optical waveguide. The present invention can also be applied to a waveguide.
[0090]
[Fourth embodiment]
FIG. 7 shows the configuration of another polarization-independent optical switch array as a fourth embodiment of the present invention. The optical switch array of this embodiment includes eight directional coupling circuits (optical coupling circuits) 7A06a, 7A06b, 7B06a, 7B06b, 7A11a, 7A11b, 7B11a, 7B11b, and eight polarization multiplexing / demultiplexing circuits 7A02a, 7A02b. , 7B02a, 7B02b, 7A15a, 7A15b, 7B15a, 7B15b, two comb-shaped half-wave plates 704, 713, and an eight-sequence optical phase control circuit array (detailed later).
[0091]
In other words, the optical switch array of this embodiment includes a first polarization control circuit array (7A02a, 7A02b, 7B02a, 7B02b, 704), and a first optical coupling circuit array (7A06a, 7A06b, 7B06a, 7B06b). The optical phase control circuit array, the second optical coupling circuit (7A11a, 7A11b, 7B11a, 7B11b) and the second polarization control circuit array (713, 7A15a, 7A15b, 7B15a, 7B15b) are sequentially connected. The 2 × 2 optical switch array in which two 2 × 2 optical switches are arranged in parallel vertically.
[0092]
In this example, LiNbO is formed on the substrate of the dual 2 × 2 optical switch array. _Three Z-cut is used. Also, input optical waveguides 7A01a, 7A01b, 7B01a, 7B01b, output optical waveguides 7A16a, 7A16b, 7B16a, 7B16b, other optical waveguides 7A03a, 7A03b, 7A03c, 7A03d, 7B03a, 7B03b, 7B03c, 7B03d, 7A05a7 7A05d, 7B05a, 7B05b, 7B05c, 7B05d, 7A07a, 7A07b, 7A07c, 7A07d, 7B07a, 7B07b, 7B07c, 7B07d, 7A10a, 7A10b, 7A10c, 7A10d, 7B10a, 7B10b, 7d, 7B10,7d Ti diffusion optical waveguides are used as 7B12a, 7B12b, 7B12c, 7B12d, 7A14a, 7A14b, 7A14c, 7A14d, 7B14a, 7B14b, 7B14c, and 7B14d.
[0093]
The optical phase control circuit array of this embodiment is a phase shift circuit, as shown in FIG. 5, with signal electrode wirings 7A09a, 7A09b, 7A09c, 7A09d, 7B09a, 7B09b, 7B09c, 7B09d and ground electrode wirings 7A08a, 7A08b, 7A08c, 7A08d. , 7B08a, 7B08b, 7B08c, 7B08d are loaded.
[0094]
Therefore, the configuration of the optical phase control circuit array is similar to that shown in FIG. However, in this embodiment, each optical waveguide 7A07a, 7A07b connecting the first optical coupling circuit array (7A06a, 7A06b, 7B06a, 7B06b) and the second optical coupling circuit array (7A11a, 7A11b, 7B11a, 7B11b). , 7A07c, 7A07d, 7B07a, 7B07b, 7B07c, 7B07d are loaded with signal electrodes 7A09a, 7A09b, 7A09c, 7A09d, 7B09a, 7B09b, 7B09c, 7B09d on top of which the electrical signals for phase control are guided. It plays a role as an optical phase control circuit for performing phase control. The ground electrodes 7A08a, 7A08b, 7A08c, 7A08d, 7B08a, 7B08b, 7B08c, and 7B08d are loaded beside each signal electrode.
[0095]
The directional coupling circuits 7A06a, 7A11a and the optical waveguides 7A07a, 7A10a, 7A07b, 7A10b and signal electrodes 7A09a, 7A09b between them, and the directional coupling circuits 7A06b, 7A11b and the optical waveguides 7A07c, 7A10d, 7A07c, 7A10d And signal electrodes 7A09c, 7A09d, directional coupling circuits 7B06a, 7B11a and optical waveguides 7B07a, 7B10a, 7B07b, 7B10b and signal electrodes 7B09a, 7B09b, and directional coupling circuits 7B06b, 7B11b Each of the combinations of the waveguides 7B07c, 7B10c, 7B07d, 7B10d and the signal electrodes 7B09c, 7B09d operates as a Mach-Zehnder interferometer switch using the electro-optic effect.
[0096]
The first polarization control circuit array is polarized between the four polarization multiplexing / demultiplexing circuits 7A02a, 7A02b, 7B02a, 7B02b and the first optical coupling circuit array (7A06a, 7A06b, 7B06a, 7B06b). This is configured by inserting a comb-like half-wave plate 704 into the output optical waveguides of the multiplexing / demultiplexing circuits 7A02a, 7A02b, 7B02a, 7B02b. The comb-shaped half-wave plate 704 is one of the eight output optical waveguides 7A03a, 7A03b, 7A03c, 7A03d, 7B03a, 7B03b, 7B03c, and 7B03d of the polarization multiplexing / demultiplexing circuits 7A02a, 7A02b, 7B02a, and 7B02b. Two every two are inserted into a total of four output optical waveguides 7A03c, 7A03d, 7B03c, and 7B03d. The comb-shaped half-wave plate 704 is formed by using two orthogonal polarized waves (for example, TM polarized wave and TE polarized wave) demultiplexed by the polarization multiplexing / demultiplexing circuits 7A02a, 7A02b, 7B02a, and 7B02b as the same polarized wave. For example, it is assumed that conversion to TM polarization is performed.
[0097]
The second polarization control circuit array is between the second optical coupling circuit array (7A11a, 7A11b, 7B11a, 7B11b) and the four polarization multiplexing / demultiplexing circuits 7A15a, 7A15b, 7B15a, 7B15b. In this configuration, a comb-shaped half-wave plate 713 is inserted into the input optical waveguides of the polarization multiplexing / demultiplexing circuits 7A15a, 7A15b, 7B15a, and 7B15b. The comb-shaped half-wave plate 713 includes two input optical waveguides 7A14a, 7A14b, 7A14c, 7A14d, 7B14a, 7B14b, 7B14c, and 7B14d in the polarization multiplexing / demultiplexing circuit every two. A total of four input optical waveguides 7A14a, 7A14b, 7B14a, and 7B14b are inserted. The comb-shaped half-wave plate 713 converts all TM polarized waves that have not been converted by the first polarization control circuit array into TE polarized waves.
[0098]
Each of the comb-shaped half-wave plates 704 and 713 is inserted into a groove formed by dividing all eight optical waveguides with the optical main axis inclined 45 degrees with respect to the substrate (optical waveguide). A portion of the groove where the comb-like half-wave plates 704 and 713 are not inserted (outlined portion) is filled with an adhesive having a refractive index substantially equal to that of the optical waveguide in order to reduce loss. However, if the loss is small, the groove may remain open. Alternatively, the grooves may be formed only in the optical waveguides 7A03c, 7A03d, 7B03c, 7B03d, 7A14a, 7A14b, 7B14a, and 7B14b into which the comb-shaped half-wave plates 704 and 713 are inserted.
[0099]
Here, the flow of the optical signal in the optical switch array shown in FIG. 7 will be described. For example, in the upper 2 × 2 optical switch, light input to the input optical waveguide 7A01a is separated into TE polarized light and TM polarized light by the polarization multiplexing / demultiplexing circuit 7A02a. A comb-like half-wave plate 704 having an optical principal axis inclined by 45 degrees is inserted into an optical waveguide 7A03c through which TE polarized light propagates, and converts TE polarized light into TM polarized light. The TM polarization separated by the polarization multiplexing / demultiplexing circuit 7A02a is equally distributed to the optical waveguides 7A07a and 7A07b by the directional coupler 7A06a, and the TM polarization converted from the TE polarization by the comb-like half-wave plate 704 is used. The waves are equally distributed to the optical waveguides 7A07c and 7A07d by the directional coupler 7A06b. These four optical waveguides 7A07a, 7A07b, 7A07c, and 7A07d are optical phase control circuits capable of changing the phase by loading electric wirings on the top. The light guided through the optical phase control circuit is guided through the optical waveguides 7A10a, 7A10b, 7A10c, and 7A10d, and is multiplexed by the directional couplers 7A11a and 7A11b. At that time, when a phase difference of half wavelength is given between the light guided through the optical waveguides 7A10a and 7A10b or the optical waveguides 7A10c and 7A10d, the directional coupling circuits 7A11a and 7A11b can transmit the optical waveguide 7A12a or the optical waveguide 7A12c. When light propagates to the optical waveguide and no phase difference is given, the light propagates to the optical waveguide 7A12b or the optical waveguide 7A12d. The optical waveguides 7A12a and 7A12b are inserted with a comb-like half-wave plate 713 whose optical principal axis is inclined by 45 degrees, and converts the propagating TM polarization into TE polarization. This comb-shaped half-wave plate 713 polarization-polarized (TE polarized wave) and non-polarized light (TM polarized wave) are combined by polarization multiplexing / demultiplexing circuits 7A15a and 7A15b and output. Propagates to the optical waveguides 7A16a and 7A16b. Therefore, an optical switch is realized by giving a desired phase difference by the phase shift circuit in the optical phase control circuit array. The same applies when light is input to the input optical waveguide 7A01b, and when light is input to the input optical waveguides 7B01a and 7B01b of the lower 2 × 2 optical switch.
[0100]
The method of giving the phase difference in the optical phase control circuit array is the same as that described with reference to FIG.
[0101]
Here, the polarization independence mechanism will be described. First, light is separated into a first TE polarized wave and a first TM polarized wave by a polarization multiplexing / demultiplexing circuit, and the first TE polarized wave is converted into a second TM polarized wave using a half-wave plate. Convert. The first TM polarization and the second TM polarization are individually switched by the first and second Mach-Zehnder interferometer switches using the electro-optic effect. At this time, since the incident light is the same and has a single polarization (TM polarization), the first Mach-Zehnder interferometer switch and the second Mach-Zehnder interference can be obtained by applying a desired electrical signal to the phase shift circuit. The meter switch operates similarly. Of the first and second Mach-Zehnder interferometer switches, one output light is converted to a second TE polarized wave, and the other output light (second TM polarized wave) is converted by a polarization multiplexing / demultiplexing circuit. The switching characteristics independent of the polarization can be obtained.
[0102]
The effect obtained by using the comb-shaped half-wave plates 704 and 713 in the first and second polarization control circuit arrays is the same as that of the third embodiment, and the crossed waveguides can be reduced. The increase in excess loss caused can be eliminated, the dependency of the cross loss on the optical path can be eliminated, and the circuit size can be reduced.
[0103]
In the present embodiment, the dual optical switch array has been described. However, the same effect can be obtained in a single optical switch having the same configuration or in an optical switch array having three or more optical switches. In this example, a lithium niobate-based optical waveguide is used as an optical waveguide having a large electro-optic effect. _1-x Nb _x O _Three Or K _1-y Li _y Ta _1-x Nb _x O _Three The same effect can be obtained even with optical waveguides using other multi-element oxide crystals such as. Furthermore, in this embodiment, the electro-optic effect is used to change the phase in the optical phase control circuit array. However, the phase can also be changed using the thermo-optic effect. In this case, an optical switch using the thermo-optic effect is realized by using, as the phase shift circuit, a heater for applying heat and a wiring for flowing current to the heater. Such a thermo-optic optical switch also has polarization dependency. Therefore, by using a thermo-optic optical switch array having a configuration using a comb-like half-wave plate similar to that of the present embodiment, the same effect as described above can be obtained and useful. In the case of a thermo-optic optical switch array, the optical waveguide is not limited to a lithium niobate-based optical waveguide, but in an optical waveguide having a thermo-optic effect, such as a multi-component optical waveguide represented by quartz glass and a plastic optical waveguide. Also, the present invention can be applied.
[0104]
[Fifth embodiment]
FIG. 8 shows a configuration of a polarization-independent optical attenuator array as a fifth embodiment of the present invention. The optical attenuator array of this embodiment includes eight directional coupling circuits (optical coupling circuits) 8A06a, 8A06b, 8B06a, 8B06b, 8A11a, 8A11b, 8B11a, 8B11b, and four polarization multiplexing / demultiplexing circuits 8A02, 8B02, 8A15, and 8B15, two comb-shaped half-wave plates 804 and 813, and eight optical phase control circuit arrays (details will be described later) are used.
[0105]
In other words, the optical attenuator array of the present embodiment includes the first polarization control circuit array (8A02, 8B02, 804), the first optical coupling circuit array (8A06a, 8A06b, 8B06a, 8B06b), and the optical phase. An optical attenuator comprising a control circuit array, a second optical coupling circuit array (8A11a, 8A11b, 8B11a, 8B11b), and a second polarization control circuit array (813, 8A15, 8B15) sequentially connected. This is a two-unit optical attenuator array arranged in parallel in two vertical directions.
[0106]
Therefore, the optical attenuator array of this embodiment has a configuration basically similar to that of the optical switch array shown in FIG. 7, but the number of polarization multiplexing / demultiplexing circuits 8A02 and 8B02 in the first polarization control circuit array. Is less than the number of directional coupling circuits 8A06a, 8A06b, 8B06a, 8B06b in the first optical coupling circuit array, and the number of polarization multiplexing / demultiplexing circuits 8A15, 8B15 in the second polarization control circuit array is second. 7 is different from the optical switch array shown in FIG. 7 in that the number of directional coupling circuits 8A11a, 8A11b, 8B11a, and 8B11b is smaller than that of the optical coupling circuit array shown in FIG.
[0107]
In this embodiment, LiNbO is formed on the substrate of the double optical attenuator array. _Three Z-cut is used. Also, the input optical waveguide 8A01, 8B01 and the output optical waveguide 8A16, 8B16, other optical waveguides 8A03a, 8A03b, 8B03a, 8B03b, 8A05a, 8A05b, 8B05a, 8B05b, 8A07a, 8A07b, 8B07a, 8B07b, 8A10a, 8A10b Ti diffusion optical waveguides are used as 8B10b, 8A12a, 8A12b, 8B12a, 8B12b, 8A14a, 8A14b, 8B14a, and 8B14b.
[0108]
The optical phase control circuit array of the present embodiment is configured as a phase shift circuit in the same manner as in FIGS. 5 and 7, including signal electrode wirings 8A09a, 8A09b, 8A09c, 8A09d, 8B09a, 8B09b, 8B09c, 8B09d, 8A08c, 8A08d, 8B08a, 8B08b, 8B08c, 8B08d are loaded.
[0109]
Also, a combination of directional coupling circuits 8A06a, 8A11a and optical waveguides 8A07a, 8A10a, 8A07b, 8A10b and signal electrodes 8A09a, 8A09b between them, directional coupling circuits 8A06b, 8A11b and optical waveguides 8A07c, 8A10d, 8A07c, 8A10d between them And signal electrodes 8A09c, 8A09d, directional coupling circuits 8B06a, 8B11a and optical waveguides 8B07a, 8B10a, 8B07b, 8B10b and signal electrodes 8B09a, 8B09b, and directional coupling circuits 8B06b, 8B11b Each of the combinations of the waveguides 8B07c, 8B10c, 8B07d, 8B10d and the signal electrodes 8B09c, 8B09d operates as a Mach-Zehnder interferometer optical switch using the electro-optic effect.
[0110]
The optical phase control circuit array has the same configuration as that of FIG. 7, and the first directional coupling circuit array (8A06a, 8A06b, 8B06a, 8B06b) and the second directional coupling circuit array (8A11a, 8A11b, 8B11a, 8B11b) Each of the optical waveguides 8A07a, 8A07b, 8A07c, 8A07d, 8B07a, 8B07b, 8B07c, 8B07d connecting between them is a signal electrode 8A09a, 8A09b, 8A09c, 8A09d, for guiding an electrical signal for phase control on the upper part thereof 8B09a, 8B09b, 8B09c, and 8B09d are loaded and serve as an optical phase control circuit that performs phase control. The ground electrodes 8A08a, 8A08b, 8A08c, 8A08d, 8B08a, 8B08b, 8B08c, and 8B08d are loaded beside each signal electrode.
[0111]
The first polarization control circuit array is configured to combine polarization between the two polarization multiplexing / demultiplexing circuits 8A02 and 8B02 and the first optical coupling circuit array (8A06a, 8A06b, 8B06a and 8B06b). A comb-shaped half-wave plate 804 is inserted into the output optical waveguide of the wave circuits 8A02 and 8B02. This comb-shaped half-wave plate 804 is inserted into the output optical waveguides 8A03b, 8B03b every other one of the four output optical waveguides 8A03a, 8A03b, 8B03a, 8B03b of the polarization multiplexing / demultiplexing circuit. Yes. The comb-shaped half-wave plate 804 converts two orthogonal polarized waves (for example, TM polarized wave and TE polarized wave) demultiplexed by the polarization multiplexing / demultiplexing circuits 8A02 and 8B02 into the same polarized wave, for example, TM polarized wave. Shall be converted to
[0112]
The second polarization control circuit array includes a polarization multiplexing / demultiplexing circuit between the second optical coupling circuit array (8A11a, 8A11b, 8B11a, 8B11b) and the two polarization multiplexing / demultiplexing circuits 8A15, 8B15. A comb-shaped half-wave plate 813 is inserted into the input optical waveguides of the circuits 8A15 and 8B15. This comb-shaped half-wave plate 813 is inserted into the input optical waveguides 8A14a, 8B14a every other one of the four input optical waveguides 8A14a, 8A14b, 8B14a, 8B14b of the polarization multiplexing / demultiplexing circuit. Yes. The comb-shaped half-wave plate 813 converts all TM polarized waves that have not been converted by the first-side polarization control circuit array into TE polarized waves.
[0113]
Each of the comb-shaped half-wave plates 804 and 813 is inserted into a groove formed by dividing all four optical waveguides with the optical main axis inclined 45 degrees with respect to the substrate (optical waveguide). The portion of the groove where the comb-like half-wave plates 804 and 813 are not inserted (outlined portions) is filled with an adhesive having a refractive index substantially equal to that of the optical waveguide in order to reduce loss. However, if the loss is small, the groove may remain open. Further, grooves may be formed only in the optical waveguides 8A03b, 8B03b, 8A14a, and 8B14a into which the comb-shaped half-wave plates 804 and 813 are inserted.
[0114]
The optical signal flow in the optical attenuator array shown in FIG. 8 is the same as that in the fourth embodiment. For example, light input to the input optical waveguide 8A01 is separated into TE polarized light and TM polarized light by the polarization multiplexing / demultiplexing circuit 8A02. A comb-like half-wave plate 804 having an optical principal axis inclined by 45 degrees is inserted into an optical waveguide 8A03b through which TE polarized light propagates, and converts TE polarized light into TM polarized light. The TM polarization separated by the polarization multiplexing / demultiplexing circuit 8A02 is equally distributed to the optical waveguides 8A07a and 8A07b by the directional coupler 8A06a, and the TM polarization converted from the TE polarization by the comb-shaped half-wave plate 804 is used. The waves are equally distributed to the optical waveguides 8A07c and 8A07d by the directional coupler 8A06b. These four optical waveguides 8A07a, 8A07b, 8A07c, and 8A07d are optical phase control circuits that are equipped with electric wirings on the top and can change the phase. The light guided through the optical phase control circuit is guided through the optical waveguides 8A10a, 8A10b, 8A10c, and 8A10d, and is multiplexed by the directional couplers 8A11a and 8A11b, respectively. At that time, when a phase difference of half wavelength is given between the light guided through the optical waveguides 8A10a and 8A10b or the optical waveguides 8A10c and 8A10d, the directional coupling circuits 8A11a and 8A11b can transmit the optical waveguide 8A12a or the optical waveguide 8A12b. When the phase difference is not given, the light does not propagate to the optical waveguide 8A12a or the optical waveguide 8A12b. The optical waveguide 8A12a is inserted with a comb-like half-wave plate 813 whose optical principal axis is inclined by 45 degrees, and converts propagating TM polarized light into TE polarized light. Polarization combining of the polarization-converted (TE polarization) by the comb-shaped half-wave plate 813 and the light not subjected to polarization conversion (TM polarization) is performed by the polarization multiplexing / demultiplexing circuit 8A15, and the output optical waveguide Propagate to 8A16. Therefore, by providing a desired phase difference with the optical phase control circuit array (8A07a, 8A07b, 8A07c, 8A07d), the light emitted from the output optical waveguide 8A16 can be quenched. Similarly, when light is input to the input optical waveguide 8B01, the light output from the output optical waveguide 8B16 is quenched by giving a desired phase difference by the optical phase control circuit array (8B07a, 8B07b, 8B07c, 8B07d). Can do. Then, by adjusting the phase difference given by the optical phase control circuit array (8A07a, 8A07b, 8A07c, 8A07d, 8B07a, 8B07b, 8B07c, 8B07d), the light emitted from the output optical waveguides 8A16, 8B16 has a desired light intensity. And an optical attenuator array is realized.
[0115]
The optical attenuator array can realize light intensity control such as light intensity modulation and on / off depending on how the light intensity is set.
[0116]
The method of giving the phase difference in the optical phase control circuit array is the same as that described with reference to FIG.
[0117]
The mechanism for making the polarization independent is the same as in the fourth embodiment. First, light is separated into a first TE polarized wave and a first TM polarized wave by a polarization multiplexing / demultiplexing circuit, and the first TE polarized wave is converted into a second TM polarized wave using a half-wave plate. Convert. The first TM polarization and the second TM polarization are individually switched by the first and second Mach-Zehnder interferometer switches using the electro-optic effect. At this time, since the incident light is the same and has a single polarization (TM polarization), the first Mach-Zehnder interferometer switch and the second Mach-Zehnder interference can be obtained by applying a desired electrical signal to the phase control circuit. The meter switch operates similarly. Of the first and second Mach-Zehnder interferometer switches, one output light is converted to a second TE polarized wave, and the other output light (second TM polarized wave) is converted by a polarization multiplexing / demultiplexing circuit. Are combined to obtain polarization-independent optical attenuation characteristics.
[0118]
The effect obtained by using the comb-shaped half-wave plates 804 and 813 in the first and second polarization control circuit arrays is the same as that of the fourth embodiment, and the number of crossed waveguides can be reduced. The increase in excess loss can be eliminated, the dependency of the cross loss on the optical path can be eliminated, and the circuit size can be reduced.
[0119]
In the present embodiment, the dual optical attenuator array has been described. However, the same effect can be obtained with a single optical attenuator having the same configuration or an optical attenuator array with three or more optical attenuators. In this example, a lithium niobate-based optical waveguide is used as an optical waveguide having a large electro-optic effect. _1-x Nb _x O _Three Or K _1-y Li _y Ta _1-x Nb _x O _Three The same effect can be obtained even with optical waveguides using other multi-element oxide crystals such as. Furthermore, in this embodiment, the electro-optic effect is used to change the phase in the optical phase control circuit array. However, the phase can also be changed using the thermo-optic effect. In this case, an optical switch using the thermo-optic effect is realized by using, as the phase shift circuit, a heater for applying heat and a wiring for flowing current to the heater. Such a thermo-optic optical switch also has polarization dependency. Therefore, by using a thermo-optic optical switch array having a configuration using a comb-like half-wave plate similar to that of the present embodiment, the same effect as described above can be obtained and useful. In the case of a thermo-optic optical switch array, the optical waveguide is not limited to a lithium niobate-based optical waveguide, and in an optical waveguide having a thermo-optic effect, such as a multi-component optical waveguide represented by quartz glass, a plastic optical waveguide, The present invention can be applied.
[0120]
The feature of this embodiment is that it can be used as an optical attenuator to reduce the number of circuits constituting them, particularly the number of polarization multiplexing / demultiplexing circuits, compared to 2 × 2 optical switches. That is, there are the following merits (1) and (2).
(1) Since the number of circuits is small compared to the 2 × 2 optical switches of the third and fourth embodiments, an optical circuit can be manufactured with a high yield.
(2) Since there are few crossing waveguides compared to the 2 × 2 optical switch of the fourth embodiment, an optical circuit with lower loss can be provided.
[0121]
[Sixth embodiment]
Next, a polarization-independent optical modulator array will be described as a sixth embodiment of the present invention. The polarization-independent optical modulator array of this embodiment has two units, and the configuration diagram thereof is the same as FIG. The circuit configuration, optical signal flow, and polarization-independent mechanism of the dual-polarization-independent optical modulator array are the same as those in the third embodiment described with reference to FIG. To do.
[0122]
The polarization-independent optical modulator array of this embodiment is characterized in that the three optical circuit groups 15, 16, and 17 divided in the line segment B1-B2 and the line segment B3-B4 in FIG. After being individually manufactured on different substrates, the optical waveguides are optically coupled to each other by abutting the substrates at the end faces.
[0123]
The first optical circuit group 15 includes a first optical coupling circuit array (5A02, 5B02) and a first polarization control circuit array (polarization multiplexing / demultiplexing circuits 5A05a, 5A05b, 5B05a, 5B05b, comb-like 1 / The first optical coupling circuit array and the first polarization control circuit array are connected in order. The first optical circuit group 15 uses a quartz optical waveguide formed on a silicon substrate.
[0124]
The second optical circuit group 16 is an optical phase control circuit array, and an input / output optical waveguide connected to the output optical waveguides 5A06a, 5A06b, 5A06c, 5A06d, 5B06a, 5B06b, 5B06c, 5B06d of the first optical circuit group 15 (5A08a, 5A09a), (5A08b, 5A09b), (5A08c, 5A09c), (5A08d, 5A09d), (5B08a, 5B09a), (5B08b, 5B09b), (5B08c, 5B09c), (5B08d, 5B09d) and these A phase shift circuit (5A11a, 5A11b, 5A11c, 5A11d, 5B11a, 5B11b, 5B11c, 5B11d) loaded on the input / output optical waveguide of the first optical circuit group. As many as 15 output optical waveguides. The second optical circuit group 16 includes a Z-cut LiNbO. _Three A Ti diffusion optical waveguide formed on the substrate is used.
[0125]
The third optical circuit group 17 includes a second polarization control circuit array (polarization multiplexing / demultiplexing circuits 5A14a, 5A14b, 5B14a, 5B14b and a comb-like half-wave plate 512), and a second optical coupling circuit array. (5A17, 5B17), and the second polarization control circuit array and the second optical coupling circuit array are connected in order. As in the first optical circuit group 15, a quartz-based optical waveguide formed on a silicon substrate is used for the third optical circuit group 17.
[0126]
Here, the optical waveguide will be described in detail, and the loss in connecting the substrate will be described.
(1) The silica-based optical waveguide has a square core and is embedded in the cladding, and an optical waveguide having a relative refractive index difference between the core and the cladding of 0.75% and a spot size of 3.6 μm is used. Yes.
(2) On the other hand, LiNbO _Three As the Ti diffusion optical waveguide on the substrate, a spot size having a radius of 3.6 μm is used.
{Circle around (3)} Since the Ti diffusion optical waveguide is very close to the spot size of the silica-based optical waveguide, it can be coupled with low loss.
(4) Further, since the substrates are brought into contact with each other at the end face and connected together, the positional deviation tolerance against the coupling loss is large.
(5) Therefore, when AR coating was applied to the end face to remove Fresnel reflection, and end face coupling was performed, an extremely low loss value of 0.2 dB on average was obtained as the coupling loss, and the loss variation was within 0.1 dB. It was.
[0127]
This end face connection method is technically equivalent to a method of connecting a PLC substrate and an optical fiber array, which has a sufficient track record including reliability, and is also expected to have sufficient reliability.
[0128]
Next, effects obtained by using the comb-shaped half-wave plates 507 and 512 in the polarization control circuit array will be described below.
[0129]
In order to explain the effect of the comb-shaped half-wave plate, FIG. 11 shows a similar dual-mode light modulator using a normal half-wave plate instead of the comb-shaped half-wave plate. A configuration in the case of producing an array is shown.
[0130]
In FIG. 11, 1101a-1101d is an input optical waveguide, 1102a-1102b and 1109a-1109b are directional coupling circuits (triangle marks), 1103a-1103d and 1108a-1108d are polarization multiplexing / demultiplexing circuits (elliptical marks) , 1104 and 1107 are normal half-wave plates, 1105 is a signal electrode, 1106 is a ground electrode, 1110a-1110d are output optical waveguides, and 1111 is a crossed waveguide (circle mark). For simplicity, other optical waveguide symbols are omitted. Paths A and B are two optical paths between the two polarization multiplexing / demultiplexing circuits 1103a and 1108a in the uppermost stage. The path A has no cross waveguide, and the path B has a cross waveguide in the middle. 1111 is present.
[0131]
As shown in FIG. 11, when an attempt is made to produce a polarization-independent optical modulator array using conventional half-wave plates 1104, 1107 that are not comb-shaped, the half-wave plates 1104, 1107 are inserted. Since the optical waveguide and the optical waveguide that is not inserted need to be combined, the crossed waveguide 1111 has become indispensable. For example, even when a quartz optical waveguide as in this embodiment is used, when a cross waveguide 1111 having a cross angle of 40 degrees is produced, a cross loss of 0.2 dB per point is generated. The intersection angle of 40 degrees indicates a value at which the intersection loss is minimized. Therefore, when a double optical modulator array similar to that of the present embodiment is configured using normal half-wave plates 1104 and 1107, a large number of crossed waveguides 1110 are required as shown in FIG. .2dB crossing loss occurs.
[0132]
On the other hand, in this embodiment, although the excess loss due to the substrate connection (0.4 dB at both ends) increases, there is no cross loss because the comb-like half-wave plates 507 and 512 (see FIG. 5) are used. It became possible to suppress excessive loss sufficiently.
[0133]
In addition, since the comb-shaped half-wave plates 507 and 512 are used, the cross waveguide caused by the routing of the optical waveguide can be removed, so that the dependency of the cross loss on the optical path can be eliminated.
[0134]
When a normal half-wave plate is used, excess loss due to the crossed waveguide 1111 is greatly different between the path A and the path B, as shown in FIG. The excess loss is 0 dB in the path A, and the excess loss is 1 dB in the path B. Due to the mismatch of excess loss between the paths, even if the directional coupling circuits 1102a-1102b in the previous stage are equally distributed to the branching ratio of 50%, the branching ratio is greatly shifted as a result. Cause extinction ratio degradation.
[0135]
However, with the configuration using the comb-like half-wave plates 507 and 512 as in this embodiment, excess loss (cross loss) due to the cross waveguide is removed, so that the cross loss depends on the optical path. Is also resolved. Therefore, it is possible to suppress deterioration of the optical modulator characteristics due to the dependency of the cross loss on the optical path.
[0136]
Further, it is not necessary to route the optical waveguide, and the circuit size can be reduced. For example, in this embodiment, the circuit length can be reduced by about 1 mm as compared with the conventional configuration using a normal half-wave plate.
[0137]
In the present embodiment, the dual optical modulator array has been described. However, the same effect can be obtained with an optical modulator having a similar configuration or with an optical modulator array having three or more optical modulators. In this example, a lithium niobate-based optical waveguide is used as an optical waveguide having a large electro-optic effect. _1-x Nb _x O _Three Or K _1-y Li _y Ta _1-x Nb _x O _Three The same effect can be obtained even with optical waveguides using other multi-element oxide crystals such as. Furthermore, in this embodiment, the electro-optic effect is used to change the phase in the optical phase control circuit array. However, the phase can also be changed using the thermo-optic effect. In this case, an optical modulator using a thermo-optic effect is realized by using a heater for applying heat and a wiring for passing a current through the heater as the phase shift circuit. However, such a thermo-optic light modulator also has polarization dependency. Therefore, by using a thermo-optic type optical modulator array having a configuration using a comb-like half-wave plate similar to that of the present embodiment, the same effect as described above can be obtained and useful. In the case of a thermo-optic type optical modulator array, the optical waveguide is not limited to a lithium niobate optical waveguide, but also in an optical waveguide having a thermo-optic effect such as a multi-component optical waveguide represented by quartz glass and a plastic optical waveguide. The present invention can be applied.
[0138]
In this embodiment, a silicon substrate and a silica-based optical waveguide formed thereon are used for the first optical circuit group 15 including the first optical coupling circuit array and the first polarization control circuit array, and an optical phase control circuit is used. The second optical circuit group 16 including the array includes a Z-cut LiNbO. _Three A silicon substrate and a third optical circuit group 17 including the second polarization control circuit array and the first optical coupling circuit array are formed on the substrate and the Ti diffusion optical waveguide formed thereon. Since a quartz optical waveguide is used, there are advantages (1) to (3) below.
(1) LiNbO _Three Compared with Ti diffusion optical waveguide on substrate, quartz optical waveguide on silicon substrate is much easier to groove (for insertion of comb-like half-wave plates 507,512) and polarization independent optical modulator The fabrication of the array can be simplified.
(2) The first and third optical circuit groups 15 and 17 that need to be fiber-connected to the outside are made of silica-based optical waveguides, so that they can be connected with low loss and high reliability. . The reason for this is that silica-based optical waveguides are compatible with commonly used optical fibers and have good compatibility, and the mode field diameter is almost the same as that of optical fibers, so they have low loss and high reliability. Because it is.
(3) Quartz-based optical waveguides can be used to produce large-scale circuits with low loss like AWG. Therefore, by making the first and third optical circuit groups 15 and 17 and the AWG on the same substrate, it is possible to realize high functionality such as a wavelength selector and OADM.
[0139]
[Application to FIGS. 7 and 8]
The sixth embodiment can be applied to the polarization-independent optical switch array shown in FIG. 7 or the polarization-independent optical attenuator array shown in FIG.
[0140]
When applied to the polarization-independent optical switch array of FIG. 7, the three optical circuit groups 18, 19, and 20 divided in the line segment C1-C2 and the line segment C3-C4 in FIG. After being individually manufactured on different substrates, the optical waveguides are optically coupled to each other by abutting the substrates at the end faces.
[0141]
Specifically, the first optical circuit group 18 includes a first polarization control circuit array (polarization multiplexing / demultiplexing circuits 7A02a, 7A02b, 7B02a, 7B02b and a comb-shaped half-wave plate 704), a first Optical coupling circuit arrays (7A06a, 7A06b, 7B06a, 7B06b), and the first polarization control circuit array and the first optical coupling circuit array are connected in order. The first optical circuit group 18 uses a quartz optical waveguide formed on a silicon substrate.
[0142]
The second optical circuit group 19 is an optical phase control circuit array, and input / output optical waveguides (7A07a, 7A10a), (7A07b, 7A10b), (7A07c,) connected to the output optical waveguides of the first optical circuit group 18. 7A10c), (7A07d, 7A10d), (7B07a, 7B10a), (7B07b, 7B10b), (7B07c, 7B10c), (7B07d, 7B10d) Phase shift circuits (7A09a, 7A09b, 7A09c, 7A09d, 7B09a, 7B09b, 7B09c, 7B09d), and the number of input / output optical waveguides is the same as the number of output optical waveguides of the first optical circuit group 18. The second optical circuit group 19 includes a Z-cut LiNbO. _Three A Ti diffusion optical waveguide formed on the substrate is used.
[0143]
The third optical circuit group 20 includes a second optical coupling circuit array (7A11a, 7A11b, 7B11a, 7B11b) and a second polarization control circuit array (polarization multiplexing / demultiplexing circuits 7A15a, 7A15b, 7B15a, 7B15b and combs). The second optical coupling circuit array and the second polarization control circuit array are connected in order. As in the first optical circuit group 18, a silica-based optical waveguide formed on a silicon substrate is used for the third optical circuit group 20.
[0144]
When applied to the polarization-independent optical attenuator array of FIG. 8, the three optical circuit groups 21, 22, and 23 divided in the line segment D1-D2 and the line segment D3-D4 in FIG. After the substrates are individually fabricated on different substrates, they are fabricated by abutting the substrates at the end faces and optically coupling the optical waveguides.
[0145]
Specifically, the first optical circuit group 21 includes a first polarization control circuit array (polarization multiplexing / demultiplexing circuits 8A02 and 8B02 and a comb-shaped half-wave plate 804), and a first optical coupling circuit. Array (8A06a, 8A06b, 8B06a, 8B06b), and the first polarization control circuit array and the first optical coupling circuit array are sequentially connected. The first optical circuit group 21 uses a quartz optical waveguide formed on a silicon substrate.
[0146]
The second optical circuit group 22 is an optical phase control circuit array, and input / output optical waveguides (8A07a, 8A10a), (8A07b, 8A10b), (8A07c,) connected to the output optical waveguides of the first optical circuit group 21. 8A10c), (8A07d, 8A10d), (8B07a, 8B10a), (8B07b, 8B10b), (8B07c, 8B10c), (8B07d, 8B10d) Phase shift circuits (8A09a, 8A09b, 8A09c, 8A09d, 8B09a, 8B09b, 8B09c, 8B09d) and the same number of input / output optical waveguides as the output optical waveguides of the first optical circuit group 21. The second optical circuit group 22 includes a Z-cut LiNbO. _Three A Ti diffusion optical waveguide formed on the substrate is used.
[0147]
The third optical circuit group 24 includes a second optical coupling circuit array (8A11a, 8A11b, 8B11a, 8B11b), a second polarization control circuit array (polarization multiplexing / demultiplexing circuits 8A15, 7B15, comb-like 1 / The second optical coupling circuit array and the second polarization control circuit array are connected in order. As in the first optical circuit group 21, a quartz-based optical waveguide formed on a silicon substrate is used for the third optical circuit group 24.
[0148]
Even if the first optical circuit group 18, the second optical circuit group 19 and the third optical circuit group 20 produced individually are connected to each other to produce the polarization-independent optical switch array of FIG. Further, the first optical circuit group 21, the second optical circuit group 22, and the third optical circuit group 23 manufactured individually are connected to each other to manufacture the polarization-independent optical attenuator array shown in FIG. However, as can be seen from the description of the present embodiment, since the connection can be made with a sufficiently small loss, the effect of using the comb-shaped half-wave plate can be sufficiently expected and effective.
[0149]
[Seventh embodiment]
Next, a polarization-independent optical switch array will be described as a seventh embodiment of the present invention. The polarization-independent optical switch array of this embodiment has two units, and the configuration diagram thereof is the same as FIG. The circuit configuration, optical signal flow, and polarization-independent mechanism of the dual-polarization-independent optical switch array are the same as those in the third embodiment described with reference to FIG. .
[0150]
The characteristic of the polarization-independent optical modulator array of this embodiment is that the three optical circuit groups 15, 16, and 17 divided in the line segments B1-B2 and B3-B4 in FIG. After being individually manufactured on different substrates, the optical waveguides are optically coupled to each other by abutting the substrates at the end faces.
[0151]
The first optical circuit group 15 includes a first optical coupling circuit array (5A02, 5B02) and a first polarization control circuit array (polarization multiplexing / demultiplexing circuits 5A05a, 5A05b, 5B05a, 5B05b, comb-like 1 / The first optical coupling circuit array and the first polarization control circuit array are connected in order. The first optical circuit group 15 includes a Z-cut LiNbO. _Three A Ti diffusion optical waveguide formed on the substrate is used.
[0152]
The second optical circuit group 16 is an optical phase control circuit array, and an input / output optical waveguide connected to the output optical waveguides 5A06a, 5A06b, 5A06c, 5A06d, 5B06a, 5B06b, 5B06c, 5B06d of the first optical circuit group 15 (5A08a, 5A09a), (5A08b, 5A09b), (5A08c, 5A09c), (5A08d, 5A09d), (5B08a, 5B09a), (5B08b, 5B09b), (5B08c, 5B09c), (5B08d, 5B09d) and these A phase shift circuit (5A11a, 5A11b, 5A11c, 5A11d, 5B11a, 5B11b, 5B11c, 5B11d) loaded on the input / output optical waveguide of the first optical circuit group. As many as 15 output optical waveguides. The second optical circuit group 16 includes a Z-cut LiNbO. _Three A Ti diffusion optical waveguide formed on the substrate is used.
[0153]
The third optical circuit group 17 includes a second polarization control circuit array (polarization multiplexing / demultiplexing circuits 5A14a, 5A14b, 5B14a, 5B14b and a comb-like half-wave plate 512), and a second optical coupling circuit array. (5A17, 5B17), and the second polarization control circuit array and the second optical coupling circuit array are connected in order. As in the first and second optical circuit groups 15 and 16, the third optical circuit group 17 includes a Z-cut LiNbO. _Three A Ti diffusion optical waveguide formed on the substrate is used.
[0154]
Here, the optical waveguide will be described in detail, and the loss in connecting the substrate will be described.
▲ １ ▼ LiNbO _Three As the Ti diffusion optical waveguide on the substrate, a spot size having a radius of 3.6 μm is used.
(2) After AR coating was applied to the end face to remove Fresnel reflection, end face bonding was performed. As a result, a very low loss value of 0.1 dB on average was obtained as a coupling loss, and the loss variation was within 0.1 dB.
{Circle around (3)} Since the substrates are brought together at the end faces and connected together, the displacement tolerance against the coupling loss is large.
[0155]
This end face connection method is technically equivalent to a method of connecting a PLC substrate and an optical fiber array, which has a sufficient track record including reliability, and is also expected to have sufficient reliability.
[0156]
Next, the effects of using the comb-shaped half-wave plates 507 and 512 in the polarization control circuit array will be described below in comparison with the optical circuit of FIG.
(1) As shown in FIG. 11, when an attempt is made to produce a polarization-independent optical switch array using conventional half-wave plates 1104, 1107 that are not comb-shaped, the half-wave plates 1104, 1107 are Since the optical waveguide to be inserted and the optical waveguide not to be inserted need to be put together, the crossed waveguide 1111 has been indispensable. For example, LiNbO as in this example _Three Even when the Ti diffusion optical waveguide on the substrate is used, if a cross waveguide 1111 having a cross angle of 40 degrees is produced, a cross loss of 0.2 dB per point is generated. Therefore, when a duplex optical switch array similar to that of the present embodiment is configured using normal half-wave plates 1104 and 1107, a large number of crossed waveguides 1110 are required as shown in FIG. Crossing loss of 2dB occurs.
(2) On the other hand, in this embodiment, although the excess loss due to the substrate connection (0.4 dB at both ends) increases, the comb-like half-wave plates 507 and 512 (see FIG. 5) are used, so the cross loss. Therefore, excess loss can be suppressed sufficiently.
(3) Since the comb-shaped half-wave plates 507 and 512 are used, the cross waveguide caused by the routing of the optical waveguide can be removed, so that the dependency of the cross loss on the optical path can be eliminated.
(4) When a normal half-wave plate is used, the excess loss due to the crossed waveguide 1111 is greatly different between the path A and the path B as shown in FIG. The excess loss is 0 dB in the path A, and the excess loss is 1 dB in the path B. Due to the mismatch of excess loss between the paths, even if the directional coupling circuits 1102a-1102b in the previous stage are equally distributed to the branching ratio of 50%, the branching ratio is greatly shifted as a result. As a result, the extinction ratio deteriorates.
(5) However, by using the comb-shaped half-wave plates 507 and 512 as in this embodiment, excess loss (crossing loss) due to the crossing waveguide is removed, so that the light of crossing loss can be obtained. Route dependency is also eliminated. Therefore, it is possible to suppress the deterioration of the characteristics of the optical switch due to the dependency of the crossing loss on the optical path.
(6) Furthermore, it is not necessary to route the optical waveguide, and the circuit size can be reduced. For example, in this embodiment, the circuit length can be reduced by about 1 mm as compared with the conventional configuration using a normal half-wave plate.
[0157]
In the present embodiment, the dual optical switch array has been described. However, the same effect can be obtained in a single optical switch having the same configuration or in an optical switch array having three or more optical switches. In this example, a lithium niobate-based optical waveguide is used as an optical waveguide having a large electro-optic effect. _1-x Nb _x O _Three Or K _1-y Li _y Ta _1-x Nb _x O _Three The same effect can be obtained even with optical waveguides using other multi-element oxide crystals such as. Furthermore, in this embodiment, the electro-optic effect is used to change the phase in the optical phase control circuit array. However, the phase can also be changed using the thermo-optic effect. In this case, an optical switch using the thermo-optic effect is realized by using, as the phase shift circuit, a heater for applying heat and a wiring for flowing current to the heater. However, even such a thermo-optic optical switch has polarization dependency. Therefore, by using a thermo-optic optical switch array having a configuration using a comb-like half-wave plate similar to that of the present embodiment, the same effect as described above can be obtained and useful. In the case of a thermo-optic optical switch array, the optical waveguide is not limited to a lithium niobate-based optical waveguide, and in an optical waveguide having a thermo-optic effect, such as a multi-component optical waveguide represented by quartz glass, a plastic optical waveguide, The present invention can be applied.
[0158]
In the present embodiment, the first optical circuit group 15 including the first optical coupling circuit array and the first polarization control circuit array, the second optical circuit group 16 including the optical phase control circuit array, and the second polarization The third optical circuit group 17 including the control circuit array and the first optical coupling circuit array is both Z-cut LiNbO. _Three Since the substrate and the Ti diffusion optical waveguide formed thereon are used, the connection can be made with a sufficiently small loss, and therefore the effect of using the comb-shaped half-wave plate can be sufficiently expected. Further, there is an advantage that the optical switch array can be manufactured with a high yield by connecting the optical circuit groups 15, 16, and 17 after individually manufacturing them.
[0159]
[Application to FIGS. 7 and 8]
The eighth embodiment can be applied to the polarization-independent optical switch array shown in FIG. 7 or the polarization-independent optical attenuator array shown in FIG.
[0160]
When applied to the polarization-independent optical switch array of FIG. 7, the three optical circuit groups 18, 19, and 20 divided in the line segment C1-C2 and the line segment C3-C4 in FIG. After individually producing on a different board | substrate, it is produced by abutting board | substrates by an end surface and optically coupling each optical waveguide.
[0161]
Specifically, the first optical circuit group 18 includes a first polarization control circuit array (polarization multiplexing / demultiplexing circuits 7A02a, 7A02b, 7B02a, 7B02b and a comb-shaped half-wave plate 704), a first Optical coupling circuit arrays (7A06a, 7A06b, 7B06a, 7B06b), and the first polarization control circuit array and the first optical coupling circuit array are connected in order. The first optical circuit group 18 includes a Z-cut LiNbO. _Three A substrate and a Ti diffusion optical waveguide formed thereon are used.
[0162]
The second optical circuit group 19 is an optical phase control circuit array, and input / output optical waveguides (7A07a, 7A10a), (7A07b, 7A10b), (7A07c,) connected to the output optical waveguides of the first optical circuit group 18. 7A10c), (7A07d, 7A10d), (7B07a, 7B10a), (7B07b, 7B10b), (7B07c, 7B10c), (7B07d, 7B10d) Phase shift circuits (7A09a, 7A09b, 7A09c, 7A09d, 7B09a, 7B09b, 7B09c, 7B09d), and the number of input / output optical waveguides is the same as the number of output optical waveguides of the first optical circuit group 18. As in the first optical circuit group 18, the second optical circuit group 19 includes a Z-cut LiNbO. _Three A Ti diffusion optical waveguide formed on the substrate is used.
[0163]
The third optical circuit group 20 includes a second optical coupling circuit array (7A11a, 7A11b, 7B11a, 7B11b) and a second polarization control circuit array (polarization multiplexing / demultiplexing circuits 7A15a, 7A15b, 7B15a, 7B15b and combs). The second optical coupling circuit array and the second polarization control circuit array are connected in order. The third optical circuit group 20 includes a Z-cut LiNbO as in the first and second optical circuit groups 18 and 10. _Three A Ti diffusion optical waveguide formed on the substrate is used.
[0164]
When applied to the polarization-independent optical attenuator array of FIG. 8, the three optical circuit groups 21, 22, and 23 divided in the line segment D1-D2 and the line segment D3-D4 in FIG. After the substrates are individually fabricated on different substrates, they are fabricated by abutting the substrates at the end faces and optically coupling the optical waveguides.
[0165]
Specifically, the first optical circuit group 21 includes a first polarization control circuit array (polarization multiplexing / demultiplexing circuits 8A02 and 8B02 and a comb-shaped half-wave plate 804), and a first optical coupling circuit. Array (8A06a, 8A06b, 8B06a, 8B06b), and the first polarization control circuit array and the first optical coupling circuit array are sequentially connected. The first optical circuit group 21 includes a Z-cut LiNbO. _Three A Ti diffusion optical waveguide formed on the substrate is used.
[0166]
The second optical circuit group 22 is an optical phase control circuit array, and input / output optical waveguides (8A07a, 8A10a), (8A07b, 8A10b), (8A07c,) connected to the output optical waveguides of the first optical circuit group 21. 8A10c), (8A07d, 8A10d), (8B07a, 8B10a), (8B07b, 8B10b), (8B07c, 8B10c), (8B07d, 8B10d) Phase shift circuits (8A09a, 8A09b, 8A09c, 8A09d, 8B09a, 8B09b, 8B09c, 8B09d) and the same number of input / output optical waveguides as the output optical waveguides of the first optical circuit group 21. As in the first optical circuit group 21, the second optical circuit group 22 includes a Z-cut LiNbO. _Three A Ti diffusion optical waveguide formed on the substrate is used.
[0167]
The third optical circuit group 24 includes a second optical coupling circuit array (8A11a, 8A11b, 8B11a, 8B11b), a second polarization control circuit array (polarization multiplexing / demultiplexing circuits 8A15, 7B15, comb-like 1 / The second optical coupling circuit array and the second polarization control circuit array are connected in order. The third optical circuit group 24 includes a Z-cut LiNbO as in the first and second optical circuit groups 21 and 22. _Three A Ti diffusion optical waveguide formed on the substrate is used.
[0168]
Even if the first optical circuit group 18, the second optical circuit group 19 and the third optical circuit group 20 produced individually are connected to each other to produce the polarization-independent optical switch array of FIG. Further, the first optical circuit group 21, the second optical circuit group 22, and the third optical circuit group 23 manufactured individually are connected to each other to manufacture the polarization-independent optical attenuator array shown in FIG. However, as can be seen from the description of this embodiment, there is an advantage that the optical switch array can be manufactured with a high yield. In addition, since the connection can be made with a sufficiently small loss, the effect of using the comb-toothed half-wave plate can be sufficiently expected and effective.
[0169]
[Eighth embodiment]
FIG. 9 shows the configuration of a polarization-independent optical attenuator array as an eighth embodiment of the present invention. In the optical attenuator array of this embodiment, the third optical circuit group 17 is deleted from the polarization independent optical circuit (optical modulator array) of the sixth embodiment described with reference to FIG. Instead, the second optical circuit group 16 corresponds to the one provided with a reflecting surface on the output side.
[0170]
That is, the optical attenuator array of this embodiment includes two directional coupling circuits (optical coupling circuits) 9A02, 9B02, four polarization multiplexing / demultiplexing circuits 9A05a, 9A05b, 9B05a, 9B05b, and one sheet. Using a comb-shaped half-wave plate 907, eight optical phase control circuit arrays (details will be described later), and a reflecting surface 912, two optical attenuators in which these are sequentially connected are arranged in parallel. It is a wave-independent optical attenuator array. The comb-shaped half-wave plate 907 is inserted into every other optical waveguide 9A06b, 9A06d, 9B06b, 9B06d between the polarization multiplexing / demultiplexing circuits 9A05a, 9A05b, 9B05a, 9B05b and the optical phase control circuit array. The
[0171]
Two directional coupling circuits (optical coupling circuits) 9A02 and 9B02 constitute the first optical coupling circuit array, and four polarization multiplexing / demultiplexing circuits 9A05a, 9A05b, 9B05a, and 9B05b and one comb-tooth shape The half-wave plate 907 constitutes the first polarization control circuit array, and the first optical coupling circuit array and the first polarization control circuit array constitute the first optical circuit group 24. . The second optical circuit group 25 is an optical phase control circuit array.
[0172]
For the first optical circuit group 24, a silicon substrate and a quartz optical waveguide formed thereon are used. That is, the first optical coupling circuit array and the first polarization control circuit array are manufactured using a silica-based optical waveguide formed on the same silicon substrate.
[0173]
The second optical circuit group (optical phase control circuit array) 25 includes a Z-cut LiNbO having a large electro-optic effect. _Three A substrate and a Ti diffusion optical waveguide formed thereon are used.
[0174]
For the reflection surface 912, a single dielectric multilayer filter (1.55 μm band total reflection mirror) is used.
[0175]
The first optical circuit group 24 and the second optical circuit group 25 are composed of different substrates (silicon substrate and Z-cut LiNbO _Three After being manufactured individually on the substrate), the optical waveguides are optically coupled to each other by connecting the substrates to each other at the end faces.
[0176]
The reflection surface 912 is totally reflected on the output side of the second optical circuit group 25 (the end surfaces of the optical waveguides 9A09a, 9A09b, 9A09c, 9A09d, 9B09a, 9B09b, 9B09c, and 9B09d) before or after the end surfaces of the substrates are connected to each other. Have been glued to.
[0177]
The optical phase control circuit array of the second optical circuit group 25 will be described. Input / output connected to the output optical waveguides 9A06a, 9A06b, 9A06c, 9A06d, 9B06a, 9B06b, 9B06c, 9B06d of the first optical circuit group 24. Optical waveguide (9A08a, 9A09a), (9A08b, 9A09b), (9A08c, 9A09c), (9A08d, 9A09d), (9B08a, 9B09a), (9B08b, 9B09b), (9B08c, 9B09c), (9B08d, 9B09d) These input / output optical waveguides include phase shift circuits loaded on the upper and upper surfaces, etc., and the number of input / output optical waveguides is the same as the number of output optical waveguides of the first optical circuit group 24.
[0178]
As the phase shift circuit, signal electrode wirings 9A11a, 9A11b, 9A11c, 9A11d, 9B11a, 9B11b, 9B11c, 9B11d and ground electrode wirings 9A10a, 9A10b, 9A10c, 9A10d, 9B10a, 9B10b, 9B10c, 9B10d are loaded.
[0179]
That is, each of the optical waveguides 9A08a, 9A08b, 9A08c, 9A08d, 9B08a, 9B08b, 9B08c, 9B08d in the second optical circuit group 25 is loaded with signal electrodes 9A11a, 9A11b, 9A11c, 9A11d, 9B11a. , 9B11b, 9B11c, and 9B11d serve as an optical phase control circuit that performs phase control using an electrical signal for performing phase control. The ground electrodes 9A10a, 9A10b, 9A10c, 9A10d, 9B10a, 9B10b, 9B10c, and 9B10d are loaded beside each signal electrode.
[0180]
The method of giving the phase difference in the optical phase control circuit array is the same as that described with reference to FIG.
[0181]
Here, the flow of optical signals and the operation principle in the optical attenuator array shown in FIG. 9 will be described. For example, in the upper optical attenuator, light input to the input optical waveguide 9A01a is equally distributed to the optical waveguides 9A03a and 9A03b by the directional coupling circuit 9A02, and propagates to the optical waveguides 9A04a and 9A04b. The light propagating through the optical waveguides 9A04a and 9A04b is separated into TE polarization and TM polarization by the polarization multiplexing / demultiplexing circuits 9A05a and 9A05b, respectively. The optical waveguides 9A06b and 9A06d through which TE polarized light propagates are inserted with a comb-like half-wave plate 907 whose optical principal axis is inclined by 45 degrees with respect to the substrate plane, and converts TE polarized light to TM polarized light. To do. In the optical waveguides 9A08a-9A08d for performing phase control, TM polarization propagates in all. These TM polarized waves propagate from the optical waveguide 9A08a-9A08d to the optical waveguide 9A09a-9A09d. A reflection surface 912 is bonded to the end face of the optical waveguide 9A09a-9A09d, and totally reflects the propagated light (TM polarized wave). The totally reflected light follows the path described above in reverse. Therefore, the light returning from the optical waveguides 9A08b and 9A08d is converted from the TM polarization to the TE polarization by the comb-like half-wave plate 907, and returns to the optical waveguides 9A08a and 9A08c by the polarization multiplexing / demultiplexing circuits 9A05a and 9A05b, respectively. Combined with light (TM polarization), the polarization is restored. Here, when a half-wavelength phase difference is given to the light guided by the reflecting surface 912 and guided through the optical waveguides 9A08a and 9A08c and the light guided through the optical waveguides 9A08b and 9A08d, the original input optical The waveguide 9A01a becomes an output optical waveguide, and light propagates from the directional coupling circuit 9A02 to the output optical waveguide 9A01a. When no phase difference is given, light propagates from the directional coupling circuit 9A02 to the output optical waveguide 9A01b. That is, the light emitted from the optical waveguide 9A01a can be quenched by giving a desired phase difference by the optical phase control circuit. Furthermore, by adjusting the phase difference given by the optical phase control circuit, the light emitted from the optical waveguide 9A01a can be set to a desired light intensity and can be used as an optical attenuator.
[0182]
The same applies to the lower optical attenuator, and the light input to the input optical waveguide 9B01a is equally distributed to the optical waveguides 9B03a and 9B03b by the directional coupling circuit 9B02 and propagates to the optical waveguides 9B04a and 9B04b. The light propagating through the optical waveguides 9B04a and 9B04b is separated into TE polarization and TM polarization by the polarization multiplexing / demultiplexing circuits 9B05a and 9B05b, respectively. The optical waveguides 9B06b and 9B06d through which TE polarized light propagates are inserted with a comb-like half-wave plate 907 whose optical principal axis is inclined by 45 degrees with respect to the substrate plane, and converts TE polarized light to TM polarized light. To do. In the optical waveguides 9B08a-9B08d for performing phase control, TM polarization is propagated in all cases. These TM polarized waves propagate from the optical waveguide 9B08a-9B08d to the optical waveguide 9B09a-9B09d. A reflection surface 912 is bonded to the end face of the optical waveguide 9B09a-9B09d, and totally propagates the propagated light (TM polarized wave). The totally reflected light follows the path described above in reverse.
[0183]
The effect of using the polarization independence mechanism and the comb-like half-wave plate 907 is the same as in the third and sixth embodiments.
[0184]
Here, in this example, the excess loss was 0.4 dB at the end face connection, 0.5 dB at the reflection, and 2.0 dB at the circuit loss, and the total loss was 2.9 dB. Excessive loss without using a comb-like half-wave plate and without reflection is a cross loss of 1.2 dB (maximum) and a circuit loss of 2.0 dB, which is a total of 3.2 dB. Therefore, it can be seen that the optical circuit of this embodiment is also effective in terms of loss.
[0185]
As described above, the polarization-independent optical attenuator array of this embodiment has the following advantages (1) to (3).
(1) By reflecting light, the number of circuits constituting the optical attenuator can be greatly reduced.
(2) Since light reciprocates and passes through the optical phase control circuit twice, highly efficient phase control is possible.
(3) After the first optical circuit group 24 and the second optical circuit group 25 are manufactured on separate substrates, an optical attenuator can be manufactured with high yield by connecting the end faces.
[0186]
In this embodiment, the end face connection is performed after the substrates are individually manufactured. However, even if the first optical circuit group 24 and the second optical circuit group 25 are formed on the same substrate, a comb-tooth shape is obtained. The effect obtained by using the half-wave plate 907 can be similarly expected. In this case, although the yield is lowered, there is an advantage that excess loss due to end face connection can be eliminated.
[0187]
In the present embodiment, the dual optical attenuator array has been described. However, the same effect can be obtained with a single optical attenuator having the same configuration or with three or more optical attenuator rays.
[0188]
In this example, a lithium niobate-based optical waveguide is used as an optical waveguide having a large electro-optic effect. _1-x Nb _x O _Three Or K _1-y Li _y Ta _1-x Nb _x O _Three The same effect can be obtained even with optical waveguides using other multi-element oxide crystals such as.
[0189]
Furthermore, in this embodiment, the electro-optic effect is used to change the phase in the optical phase control circuit array. However, the phase can also be changed using the thermo-optic effect. In this case, an optical attenuator using the thermo-optic effect is realized by using a heater for applying heat to the optical waveguide and a wiring for supplying a current to the heater as the phase shift circuit. Such a thermo-optic type optical attenuator also has polarization dependency. Therefore, the use of a thermo-optic type optical attenuator array having a configuration using a comb-like half-wave plate similar to that of the present embodiment is useful because the same effect as described above can be obtained. In the case of a thermo-optic optical attenuator array, the optical waveguide is not limited to a lithium niobate optical waveguide, and has a thermo-optic effect such as a multi-component optical waveguide represented by quartz glass and a plastic optical waveguide. The present invention can also be applied to an optical waveguide.
[0190]
[Ninth Embodiment]
FIG. 10 shows the configuration of a polarization-independent optical attenuator array as a ninth embodiment of the present invention. In the optical attenuator array of this embodiment, the third optical circuit group 23 is deleted from the polarization-independent optical circuit (optical attenuator array) of the fifth embodiment described with reference to FIG. Instead, the second optical circuit group 22 corresponds to an output side provided with a reflecting surface.
[0191]
That is, the optical attenuator array of this embodiment includes two polarization multiplexing / demultiplexing circuits 10A02, 10B02, four directional coupling circuits (optical coupling circuits) 10A06a, 10A06b, 10B06a, 10B06b, and one sheet. Using a comb-shaped half-wave plate 1004, an array of eight optical phase control circuits (details will be described later), and a reflecting surface 1011, two optical attenuators in which these are sequentially connected are arranged in parallel. It is a wave-independent optical attenuator array. The comb-shaped half-wave plate 1011 is inserted between the polarization multiplexing / demultiplexing circuits 10A02, 10B02 and the directional coupling circuits 10A06a, 10A06b, 10B06a, 10B06b in every other optical waveguide 10A03b, 10B03b.
[0192]
Two polarization multiplexing / demultiplexing circuits 10A02 and 10B02 and one comb-shaped half-wave plate 1004 constitute a first polarization control circuit array, and four directional coupling circuits 10A06a, 10A06b, and 10B06a. , 10B06b constitute a first optical coupling circuit array, and the first polarization control circuit array and the first optical coupling circuit array constitute a first optical circuit group 26. The second optical circuit group 27 is an optical phase control circuit array.
[0193]
For the first optical circuit group 26, a silicon substrate and a quartz optical waveguide formed thereon are used. That is, the first optical coupling circuit array and the first polarization control circuit array are manufactured using a silica-based optical waveguide formed on the same silicon substrate.
[0194]
The second optical circuit group (optical phase control circuit array) 27 includes a Z-cut LiNbO having a large electro-optic effect. _Three A substrate and a Ti diffusion optical waveguide formed thereon are used.
[0195]
For the reflecting surface 1011, a single dielectric multilayer filter (1.55 μm band total reflection mirror) is used.
[0196]
The first optical circuit group 26 and the second optical circuit group 27 are composed of different substrates (silicon substrate and Z-cut LiNbO _Three After being manufactured individually on the substrate), the optical waveguides are optically coupled to each other by connecting the substrates to each other at the end faces.
[0197]
The reflection surface 1011 is totally reflected on the output side of the second optical circuit group 27 (the end surfaces of the optical waveguides 10A10a, 10A10b, 10A10c, 10A10d, 10B10a, 10B10b, 10B10c, and 10B10d) before or after the end surfaces of the substrates are connected to each other. Have been glued to.
[0198]
The optical phase control circuit array of the second optical circuit group 27 will be described. Input / output optical waveguides (10A07a, 10A10a), (10A07b, 10A10b), () connected to the output optical waveguides of the first optical circuit group 26. 10A07c, 10A10c), (10A07d, 10A10d), (10B07a, 10B10a), (10B07b, 10B10b), (10B07c, 10B10c), (10B07d, 10B10d) The number of input / output optical waveguides is the same as the number of output optical waveguides of the first optical circuit group 26.
[0199]
As the phase shift circuit, signal electrode wiring 10A09a, 10A09b, 10A09c, 10A09d, 10B09a, 10B09b, 10B09c, 10B09d and ground electrode wiring 10A08a, 10A08b, 10A08c, 10A08d, 10B08a, 10B08b, 10B08c, 10B08d are loaded.
[0200]
That is, each of the optical waveguides 10A07a, 10A07b, 10A07c, 10A07d, 10B07a, 10B07b, 10B07c, 10B07d in the second optical circuit group 27 has signal electrodes 10A09a, 10A09b, 10A09c, 10A09d loaded on the upper surface or the upper surface. It plays a role as an optical phase control circuit for performing phase control by an electrical signal for performing phase control for guiding the waves 10B09a, 10B09b, 10B09c, and 10B09d. The ground electrodes 10A08a, 10A08b, 10A08c, 10A08d, 10B08a, 10B08b, 10B08c, and 10B08d are loaded beside each signal electrode.
[0201]
The method of giving the phase difference in the optical phase control circuit array is the same as that described with reference to FIG.
[0202]
Here, the flow of optical signals and the operation principle in the optical attenuator array shown in FIG. 10 will be described. For example, in the upper optical attenuator, light input to the input optical waveguide 10A01 is separated into TE polarized light and TM polarized light by the polarization multiplexing / demultiplexing circuit 10A02. A comb-like half-wave plate 1004 having an optical principal axis inclined by 45 degrees with respect to the substrate plane is inserted into the optical waveguide 10A03b through which TE polarized light propagates, and converts the TE polarized light into TM polarized light. These lights are equally distributed to the optical waveguides 10A07a and 10A07b and the optical waveguides 10A07c and 10A07d by the directional coupling circuits 10A06a and 10A06b, respectively. These four optical waveguides 10A07a-10A07d are loaded with electrical wiring on the upper part, etc., and are optical phase control circuits capable of changing the phase. The light (TM polarized wave) guided through this optical phase control circuit propagates through the optical waveguides 10A10a, 10A10b, 10A10c, and 10A07d, and is totally reflected by the reflecting surface 1011 bonded to the end faces of these optical waveguides 10A10a-10A07d. . The totally reflected light follows the path described above in reverse. Light returning from the optical waveguides 10A07a and 10A07b is coupled by the directional coupling circuit 10A06a, and returns to the polarization multiplexing / demultiplexing circuit 10A02 via the optical waveguides 10A05a and 10A03a. The light returning from the optical waveguides 10A07c and 10A07d is coupled by the directional coupling circuit 10A06b, and when propagating through the optical waveguides 10A05b and 10A03b, the comb-like half-wave plate 1004 is converted from TM polarization to TE polarization. Return to polarization multiplexing / demultiplexing circuit 10A02. These lights are synthesized by the polarization multiplexing / demultiplexing circuit 10A02 and restored to the original polarization. Here, when a half-wavelength phase difference is given to the light guided by the reflecting surface 1011 and guided through the optical waveguides 10A07a and 10A07b and the light guided through the optical waveguides 10A07c and 10A07d, the original input optical The waveguide 10A01 becomes an output optical waveguide, and 100% of light is guided from the polarization multiplexing / demultiplexing circuit 10A02 to the output optical waveguide 10A01. When no phase difference is given, no light is guided from the polarization multiplexing / demultiplexing circuit 10A02 to the output optical waveguide 10A01. That is, the light emitted from the optical waveguide 10A01 can be quenched by giving a desired phase difference by the optical phase control circuit. Furthermore, by adjusting the phase difference given by the optical phase control circuit, the light emitted from the optical waveguide 10A01 can be set to a desired light intensity and can be used as an optical attenuator.
[0203]
The same applies to the lower optical attenuator, and the light input to the input optical waveguide 10B01 is separated into TE polarized light and TM polarized light by the polarization multiplexing / demultiplexing circuit 10B02. A comb-like half-wave plate 1004 having an optical principal axis inclined by 45 degrees with respect to the substrate plane is inserted into the optical waveguide 10B03b through which the TE polarized light propagates, and converts the TE polarized light into the TM polarized light. These lights are equally distributed to the optical waveguides 10B07a and 10B07b and the optical waveguides 10B07c and 10B07d by the directional coupling circuits 10B06a and 10B06b, respectively. These four optical waveguides 10B07a-10B07d are loaded with electrical wiring on the upper part or the like, and are optical phase control circuits capable of changing the phase. The light (TM polarized wave) guided through this optical phase control circuit propagates through the optical waveguides 10B10a, 10B10b, 10B10c, and 10B07d, and is totally reflected by the reflecting surface 1011 bonded to the end faces of these optical waveguides 10B10a-10B07d. . The totally reflected light follows the path described above in reverse.
[0204]
The polarization independence mechanism is the same as in the fourth and fifth embodiments. The effect of using the comb-shaped half-wave plate 1004 is the same as that of the fourth and fifth embodiments, and there are elimination of the optical path dependency due to the crossed waveguide, reduction of the circuit size, and the like.
[0205]
As described above, the polarization-independent optical attenuator array of this embodiment has the following advantages (1) to (3).
(1) By reflecting light, the number of circuits constituting the optical attenuator can be greatly reduced.
(2) Since light reciprocates and passes through the optical phase control circuit twice, highly efficient phase control is possible.
(3) After the first optical circuit group 26 and the second optical circuit group 27 are fabricated on separate substrates, the optical attenuators can be fabricated with high yield by connecting the end faces.
[0206]
In this embodiment, the end faces are connected after the substrates are individually manufactured. However, even if the first optical circuit group 26 and the second optical circuit group 27 are formed on the same substrate, the comb-tooth shape is obtained. The effect obtained by using the half-wave plate 1004 can be similarly expected. In that case, although the yield falls. There is an advantage that excessive loss due to end face connection can be eliminated.
[0207]
In the present embodiment, the dual optical attenuator array has been described. However, the same effect can be obtained with a single optical attenuator having the same configuration or with three or more optical attenuator rays.
[0208]
In this example, a lithium niobate-based optical waveguide is used as an optical waveguide having a large electro-optic effect. _1-x Nb _x O _Three Or K _1-y Li _y Ta _1-x Nb _x O _Three The same effect can be obtained even with optical waveguides using other multi-element oxide crystals such as.
[0209]
Furthermore, in this embodiment, the electro-optic effect is used to change the phase in the optical phase control circuit array. However, the phase can also be changed using the thermo-optic effect. In this case, an optical attenuator using the thermo-optic effect is realized by using a heater for applying heat to the optical waveguide and a wiring for supplying a current to the heater as the phase shift circuit. Such a thermo-optic type optical attenuator also has polarization dependency. Therefore, the use of a thermo-optic type optical attenuator array having a configuration using a comb-like half-wave plate similar to that of the present embodiment is useful because the same effect as described above can be obtained. In the case of a thermo-optic optical attenuator array, the optical waveguide is not limited to a lithium niobate optical waveguide, and has a thermo-optic effect such as a multi-component optical waveguide represented by quartz glass and a plastic optical waveguide. The present invention can also be applied to an optical waveguide.
[0210]
【The invention's effect】
As can be seen from the above description, according to the polarization control circuit array of the present invention and the optical circuit using the same, polarization conversion is performed with a comb-shaped half-wave plate, so that crossed waveguides are reduced. Therefore, the excess loss (cross loss) caused by the crossed waveguide can be reduced. In addition, it is possible to eliminate the dependency of the cross loss caused by the cross waveguide on the optical path. Furthermore, it is not necessary to route the optical waveguide, and the circuit size can be reduced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a polarization control circuit array as a first embodiment of the present invention.
FIG. 2 is an enlarged view showing an insertion portion of the comb-shaped half-wave plate in FIG.
FIG. 3 is a configuration diagram of a waveguide-type optical amplifier array as a second embodiment of the present invention.
4 is a diagram showing a PLC mounting substrate on which the semiconductor optical amplifier (SOA) in FIG. 3 is integrated in a hybrid manner.
FIG. 5 is a diagram showing a configuration of a polarization-independent optical switch array as third, sixth, and seventh embodiments of the present invention.
6 is a cross-sectional view taken along line A1-A2 in FIG.
FIG. 7 is a configuration diagram of a polarization-independent optical switch array as a fourth embodiment of the present invention.
FIG. 8 is a configuration diagram of a polarization-independent optical attenuator array as a fifth embodiment of the present invention.
FIG. 9 is a configuration diagram of a polarization-independent optical attenuator array as an eighth embodiment of the present invention.
FIG. 10 is a configuration diagram of a polarization-independent optical attenuator array as a ninth embodiment of the present invention.
FIG. 11 is a diagram showing the optical path dependence of cross loss when a conventional half-wave plate is used in relation to the seventh embodiment.
FIG. 12 is a configuration diagram of a conventional polarization-independent optical modulator.
FIG. 13 is a configuration diagram when a conventional polarization-independent optical modulator is arrayed.
14 is a diagram for explaining the optical path dependence of the crossing loss in FIG. 13;
[Explanation of symbols]
1, 14 Groove for inserting comb-shaped half-wave plate
2, 4 Polarization control circuit array
3 Light intensity control circuit array
5, 64 4 array semiconductor optical amplifier (SOA) device
7, 8 Solder pattern for hybrid mounting
9 Si terrace mounting section
10, 11 Optical waveguide core
12, 134 Array semiconductor optical amplifier (SOA) element driving electrode
15, 18, 21, 24, 26 First optical circuit group
16, 19, 22, 25, 27 Second optical circuit group
17, 20, 23 Third optical circuit group
28 Optical principal axis of comb-shaped half-wave plate
103, 303, 305, 507, 512, 704, 713, 804, 813, 907, 1004 comb-shaped half-wave plate
101a-101h, 301a-301d, 5A01a-5A01b, 5B01a-5B01b, 7A01a-7A01b, 7B01a-7B01b, 9A01a-9A01b, 9B01a-9B01b, 10A01, 10B01, 1201a-1201b Input optical waveguide
102a-102d, 302a-302d, 306a-306d, 5A05a-5A05b, 5B05a-5B05b, 5A14a-5A14b, 5B14a-5B14b, 7A02a-7A02b, 7B02a-7B02b, 7A15a-7A15B, 7B15a8B15, 7B15a8B15 8B15, 9A05a-9A05b, 9B05a-9B05b, 10A02, 10B02, 1202, 1216a-1216b Polarization multiplexer / demultiplexer
104a-104h, 307a-307d, 5A18a-5A18b, 5B18a-5B18b, 7A16a-7A16b, 7B16a-7B16b, 8A16, 8B16, 1217a-1217b Output optical waveguide
5A02, 5B02, 5A17, 5B17, 7A06a-7A06b, 7B06a-7B06b, 7A11a-7A11b, 7B11a-7B11b, 8A06a-8A06b, 8B06a-8B06b, 8A11a-8A11b, 8B11a-8B10, A02B11b 10B06b, 1206a-1206b, 1212a-1212b Optical coupling circuit
912, 1011 Reflective surface
1101, 1318 Crossed waveguide
1204, 1214 Normal half-wave plate (conventional)

Claims (10)

Two or more polarization multiplexing / demultiplexing circuits and one or more comb-shaped half-wave plates, wherein the comb-shaped half-wave plates are input optical waveguides of the polarization multiplexing / demultiplexing circuit or A polarization control circuit array, characterized in that an optical principal axis is inserted into one of the output optical waveguides with an inclination of 45 degrees with respect to the substrate. In an optical circuit comprising a first polarization control circuit array, a second polarization control circuit array and a polarization-dependent light intensity control circuit array,
The first polarization control circuit array, the light intensity control circuit array, and the second polarization control circuit array are sequentially connected and arranged,
The optical circuit according to claim 1, wherein the first and second polarization control circuit arrays are the polarization control circuit arrays according to claim 1. In an optical circuit comprising a first polarization control circuit array, a second polarization control circuit array and a polarization-dependent optical phase control circuit array,
The first polarization control circuit array, the optical phase control circuit array, and the second polarization control circuit array are sequentially connected and arranged,
The optical circuit according to claim 1, wherein the first and second polarization control circuit arrays are the polarization control circuit arrays according to claim 1. A first optical circuit group, a second optical circuit group, and a third optical circuit group, which are connected and arranged in order;
In the first optical circuit group, a first optical coupling circuit array and a first polarization control circuit array are connected in order,
The second optical circuit group includes the same number of input / output optical waveguides as the output optical waveguides connected to the output optical waveguides of the first optical circuit group, and the phase of the light loaded on the input / output optical waveguides. An optical phase control circuit array composed of a phase shift circuit for changing,
In the third optical circuit group, a second polarization control circuit array and a second optical coupling circuit array are connected in order,
The optical circuit according to claim 1, wherein the first and second polarization control circuit arrays are the polarization control circuit arrays according to claim 1. A first optical circuit group, a second optical circuit group, and a third optical circuit group, which are connected and arranged in order;
In the first optical circuit group, a first polarization control circuit array and a first optical coupling circuit array are connected in order,
The second optical circuit group includes the same number of input / output optical waveguides as the output optical waveguides connected to the output optical waveguides of the first optical circuit group, and the phase of the light loaded on the input / output optical waveguides. An optical phase control circuit array composed of a phase shift circuit for changing,
In the third optical circuit group, a second optical coupling circuit array and a second polarization control circuit array are connected in order,
The optical circuit according to claim 1, wherein the first and second polarization control circuit arrays are the polarization control circuit arrays according to claim 1. The optical circuit according to claim 5, wherein
The number of polarization multiplexing / demultiplexing circuits constituting the first polarization control circuit array is less than the number of optical coupling circuits constituting the first optical coupling circuit array,
An optical circuit characterized in that the number of polarization multiplexing / demultiplexing circuits constituting the second polarization control circuit array is smaller than the number of optical coupling circuits constituting the second optical coupling circuit array. The optical circuit according to claim 4, wherein
An optical circuit comprising a reflective surface on the output side of the second optical circuit group instead of the third optical circuit group. The optical circuit according to claim 5 or 6,
An optical circuit comprising a reflective surface on the output side of the second optical circuit group instead of the third optical circuit group. The optical circuit according to claim 4 or 7,
An optical circuit, wherein each optical circuit group is disposed on a different substrate, the substrates are abutted at end faces, and optical waveguides between the optical circuit groups are optically coupled to each other. The optical circuit according to claim 5, 6 or 8,
An optical circuit, wherein each optical circuit group is disposed on a different substrate, the substrates are abutted at end faces, and optical waveguides between the optical circuit groups are optically coupled to each other.

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