JPH1010588A - Waveguide type optical matrix switch - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To suppress crosstalk generated in a 2 × 2 optical switch from being output to an output port. SOLUTION: The present invention includes an optical switch unit in which a plurality of 2 × 2 optical switches 3 are arranged in a matrix, and an optical switch unit for outputting an optical signal input from an input port of the optical switch unit to a predetermined output port. The waveguide type optical matrix switch 1 is provided with a shutdown optical switch 5 in front of an output port for passing an optical signal only when the optical signal is output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type optical matrix switch for outputting an optical signal input from an input port to a predetermined output port.

[0002]

2. Description of the Related Art In recent years, in the field of information communication, with the diversification of communication needs, advancement of information exchange / transmission technology, and development of device technology, high-speed broadband service for exchanging and transmitting user information at high speed and wide band. The practical use of integrated digital networks is rapidly progressing.

In this high-speed broadband service integrated digital network, switching between devices, for example, system switching between devices and a cross-connect function are being studied using optical switches as optical signals. The switching method using an optical switch does not require an optical / electrical signal conversion function as compared with the switching method using an electronic switch, so that the line speed can be increased, the device configuration can be simplified, and the amount of hardware can be reduced.
An effect such as being independent of the transmission speed / transmission system can be expected.

As an optical matrix switch for switching this optical signal, the Institute of Electronics, Information and Communication Engineers OQE93-34
Discloses a “quartz waveguide type 8 × 8 matrix optical switch module in which drive circuits are hybrid-integrated”.

FIG. 4 is a schematic view for explaining a conventional waveguide type optical matrix switch, and in order to make the explanation easy to understand, the 8 × 8 matrix optical switch module in the above-mentioned document is replaced with 4 × 4.

That is, the waveguide type optical matrix switch 1 'has a configuration in which four input ports and four output ports are provided as line interfaces.
Six 2 × 2 optical switches 3 and eight dummy units 4 are formed on a quartz substrate 2.

This waveguide type optical matrix switch 1 '
Are completely non-blocking by the 16 2 × 2 optical switches 3, and the variation of the loss due to the number of optical switches through which the optical signal passes in the eight dummy units 4 is improved.

FIG. 5 is a configuration diagram of a 2 × 2 optical switch.
The 2 × 2 optical switch is composed of two 3 × 2 optical switches realized by an optical waveguide.
It comprises dB couplers 31 and 32, an intersection 33, and a heater 34 formed on one waveguide. This 2
Each of the 3 dB couplers 31 and 32 is an asymmetric Mach-Zehnder interferometer having an optical path length difference of half a wavelength (λ / 2).

In such a 2 × 2 optical switch, each input is cross-output when no heat is applied to the heater 34 (OFF), and when heat is applied to the heater 34 (ON), the input of the heater 34 is turned off. The refractive index of the lower optical waveguide changes, and the optical path length difference between the two waveguides is cancelled, resulting in a bar state.

That is, as shown in FIG.
At the time of F, the optical signal input from the input port (1) shown in FIG. 5 is output to the output port (B), and the optical signal input from the input port (2) is output to the output port (A). . On the other hand, when the heater is ON, the optical signal input from the input port (1) shown in FIG. 5 is output to the output port (A), and the optical signal input from the input port (2) is output to the output port (B). Is output.

The control of the cross state (heater OFF) and the bar state (heater ON) of the 2 × 2 optical switch is performed for each 2 × 2 optical switch 3 shown in FIG. The waveguide type optical matrix switch 1 'can be operated. The dummy unit 4 is also 2 × 2
The configuration is the same as that of the optical switch 3. However, the two waveguides of the 3 dB coupler are separated from each other so as not to be optically coupled, so that they are always in a cross state.

[0012]

However, such a waveguide type optical matrix switch has the following problems. That is, there is a problem that an optical signal is output from an output port other than a desired output port due to crosstalk of each 2 × 2 optical switch constituting the waveguide type optical matrix switch.

The causes of the crosstalk in the 2 × 2 optical switch are that the coupling ratios of the two 3 dB couplers do not completely match due to manufacturing variations of the optical waveguide, and that the optical path length difference deviates from a set value. There is.

The effect of the crosstalk will be described with reference to FIG. That is, the input optical signal from the input port IP ₃ in the conventional waveguide type optical matrix switch 1 ', if you try to output from the output port OP _3, the 2 × 2 optical switches 3a to bar state (heater ON) it is, optical signals reaching the dummy unit 4d via the dummy unit 4a, 2 × 2 optical switches 3a, is output from the output port OP ₃ (see FIG. NakaFutoshi solid line).

[0015] In this case, crosstalk (see the dashed line in the figure) in the 2 × 2 optical switch 3a is not caused effects to be output from the idle port DP ₁ proceeds to the dummy unit 4b, in the 2 × 2 optical switch 3b (See the broken line in the figure) indicates that the 2 × 2 optical switch 3c and the dummy unit 4
c, it is output from the output port OP ₂ through 4d. Further, crosstalk (see the broken line in the figure) in the 2 × 2 optical switch 3d causes the output port OP ₄ via the dummy unit 4c.
Output from

As described above, crosstalk is output from output ports (OP ₂ and OP _{4 in} the example of FIG. 7) other than the desired output port (OP _{3 in} the example of FIG. 7). Therefore, when the 2 × 2 optical switch is set to the cross state, it is considered that a slight heater current is supplied to correct the deviation from the set value of the optical path length difference to minimize the manufacturing error. Since the supply amount of the minute heater current is different for each 2 × 2 optical switch, control of each 2 × 2 optical switch becomes complicated, and there is a problem that much time and labor are required.

[0017]

SUMMARY OF THE INVENTION The present invention is directed to a waveguide type optical matrix switch for solving such a problem. That is, the present invention includes an optical switch unit in which a plurality of 2 × 2 optical switches are arranged in a matrix, and a waveguide type optical output unit that outputs an optical signal input from an input port of the optical switch unit to a predetermined output port. Matrix switch, before the output port,
An optical switch for passing the optical signal only when the optical signal is output is provided.

In the present invention, the optical switch provided in front of the output port allows the optical signal to pass only to the output port from which the optical signal is desired to be output, and does not allow the optical signal to pass to the output port not to be output. . For this reason, even if the crosstalk proceeds to an output port that is not desired to be output, the state is interrupted by an optical switch provided in front of the output port.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a waveguide type optical matrix switch according to the present invention. FIG. 1 is a schematic diagram illustrating an embodiment of a waveguide type optical matrix switch of the present invention, and FIGS. 2 and 3 are schematic diagrams illustrating an operation example.

That is, as shown in FIG. 1, the waveguide type optical matrix switch 1 according to the present embodiment has, for example, four input ports and four output ports as line interfaces. The 2 × 2 optical switches 3, the eight dummy units 4, and the shutdown optical switch 5 provided in front of each output port are formed on the quartz substrate 2.

This waveguide type optical matrix switch 1 has
Complete non-blocking is achieved by the 16 2 × 2 optical switches 3, and variations in loss due to the number of optical switches through which optical signals pass in the eight dummy units 4 are improved. Each 2 × 2 optical switch 3 has a configuration as shown in FIG. 5 similarly to the conventional one, and operates as shown in FIG. The eight dummy units 4 are always set in the cross state.

The shutdown optical switch 5, which is a feature of the present embodiment, has the same configuration as the 2 × 2 optical switch 3, but one of the input port and the output port is unused. .

Next, an operation example of the waveguide type optical matrix switch 1 in the present embodiment will be described. First, the operation example shown in FIG. 2 is a 1-input operation, shows the case of outputting an optical signal input from the input port IP ₃ from the output port OP _3.

In this case, the 2 × 2 optical switch 3a and the shutdown optical switch 5a are in the bar state (heater O
N), the optical signal becomes the dummy unit 4a, 2 ×
Reach the dummy unit 4d via the two-optical switch 3a,
Further output a shutdown optical switch 5a to the output port OP ₃ passes (see FIG NakaFutoshi solid line).

[0025] In this case, crosstalk (see broken line in the drawing) in the 2 × 2 optical switch 3a is not caused effect to be output from the idle port DP ₁ proceeds to the dummy unit 4b. Further, the crosstalk (see broken line in the drawing) in the 2 × 2 optical switch 3b is, the 2 × 2 optical switch 3c, the dummy unit 4c, but when you Susumo through 4d to output port OP ₂ side, to the front since the shutdown optical switch 5b provided is in the cross state (heater OFF), a state of not output to the output port OP _2.

Further, 2 × 2 crosstalk optical switch 3d (see dashed line in the drawing) tries Susumo through the dummy unit 4c to the output port OP ₄ side, but optical switch shutdown provided at the front since 5c is in the cross state (heater OFF), a state of not output to the output port OP _4.

[0027] Thus, by controlling the shutdown optical switch 5a~5c provided in front of the output port, only the shutdown optical switch 5a in front of the output ports OP ₃ is desired to output an optical signal bar state (heater ON), it is possible to suppress output of an optical signal due to crosstalk from an output port that is not desired to be output.

Further, the operation example shown in FIG. 3 is a two input operation, the input port IP ₂ optical signal inputted from the output from the output port OP _4, input ports and output an optical signal input from the IP ₃ port OP ₃ This is a case in which the output is made from.

When the optical signal input from the input port IP ₃ is output from the output port OP ₃ , the 2 × 2 optical switch 3 a and the shutdown optical switch 5 a are set to the bar state (heater ON) as in the previous example. by the) optical signal reaches the dummy unit 4d via the dummy unit 4a, 2 × 2 optical switches 3a, is further output through the shutdown optical switch 5a from the output port OP ₃ (FIG NakaFutoshi See solid line).

On the other hand, when the optical signal input from the input port IP ₂ is output from the output port OP ₄ , the 2 × 2 optical switch 3 e and the shutdown optical switch 5 c are set to the bar state (heater ON). in the optical signal is a dummy unit 4a, 4e, 2 × 2 optical switch 3c, reaching the dummy unit 4c through 3e, is further output through the shutdown optical switch 5c from the output port OP ₄ (FIG NakaFutoshi See solid line).

In such an optical signal flow, 2 × 2
The crosstalk (see the broken line in the figure) in the optical switch 3a is
It does not occur the influence to be output from the idle port DP ₁ through previous example as well as a dummy unit 4b. Also,
Crosstalk 2 × 2 optical switch 3b and the 2 × 2 optical switch 3c (see broken lines in the figure) is superimposed with the dummy unit 4c, but when you Susumo through 4d to output port OP ₂ side, the front shutdown optical switch 5b provided because that is the cross state (heater OFF), a state of not output to the output port OP _2.

Further, the crosstalk (see the dashed line in the figure) in the 2 × 2 optical switch 3d is 2 × 2 optical switch 3e, it does not occur the influence to be output from the idle port DP ₄ through 3f. Although the crosstalk in the 2 × 2 optical switch 3d becomes crosstalk in the 2 × 2 optical switch 3e and is superimposed on the optical signal from the input port IP2, there is no influence because the intensity is small.

Thus, even in the case of two inputs, the output ports OP ₃ , OP ₄ for which an optical signal is to be output are controlled by controlling the shutdown optical switches 5 a to 5 c provided in front of the output ports. By setting only the shut-down optical switches 5a and 5c in the bar state (heater ON), it is possible to suppress output of an optical signal due to crosstalk from an output port that is not desired to be output.

In the above-described embodiment, an example in which four input ports and four output ports are provided has been described as an example, and mainly the case of one input and two inputs has been described. With output ports, one input and two
The same applies to the case where an input other than the input is performed. Further, the same configuration as the 2 × 2 optical switch 3 is applied as the shutdown optical switch 5 for suppressing the crosstalk, but an optical gate switch with one input and one output, an optical modulator, or the like may be applied. .

Further, the control of the shutdown optical switch 5 may be performed based on the input state of the optical signal to the waveguide type optical matrix switch 1 and the connection information of the 2 × 2 optical switch 3. Further, the optical output intensity from the waveguide type optical matrix switch 1 is monitored, and when the optical output is below a certain level, the shutdown optical switch 5 is set to the cross state (heater OFF).
May be controlled.

As the shutdown optical switch 5, the same configuration as the 2 × 2 optical switch 3 is connected in one stage. However, in order to further suppress the crosstalk, the same configuration as the 2 × 2 switch 3 is used. May be connected in multiple stages.

[0037]

As described above, the waveguide type optical matrix switch of the present invention has the following effects.
That is, by providing an optical switch in front of each output port that allows the optical output to pass only when the optical output is output, it is possible to suppress output of crosstalk from an output port that does not want to output an optical signal. Become like This makes it possible to greatly improve the switching characteristics of the waveguide type optical matrix switch.

The optical switch provided in front of the output port can be easily controlled by an external control device, for example, a hardware switch or software setting, so that complicated control is not required. Since it can be formed on a substrate like other 2 × 2 optical switches,
It can be easily integrated.

Further, since only one optical switch needs to be added before each output port, it is possible to easily cope with a case where the switch size is increased or decreased.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an embodiment of the present invention.

FIG. 2 is a schematic diagram (part 1) illustrating an operation example;

FIG. 3 is a schematic diagram (part 2) illustrating an operation example;

FIG. 4 is a schematic diagram illustrating a conventional example.

FIG. 5 is a configuration diagram of a 2 × 2 optical switch.

FIG. 6 is a diagram illustrating the operation of a 2 × 2 optical switch.

FIG. 7 is a schematic diagram illustrating an operation of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 waveguide type optical matrix switch 2 substrate 3 2 × 2 optical switch 4 dummy unit 5 optical switch for shutdown

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayasu Yamaguchi 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Akira Himeno 3-192, Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation (72) Inventor Toshimi Kominato 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo

Claims (1)

[Claims] 1. A waveguide type optical matrix comprising an optical switch unit in which a plurality of 2 × 2 optical switches are arranged in a matrix and outputting an optical signal input from an input port of the optical switch unit to a predetermined output port. A waveguide type optical matrix switch, comprising a switch in front of the output port, the optical switch allowing the optical signal to pass only when the optical signal is output.