JP2004226769A - Optical transmitter - Google Patents

Abstract

An object of the present invention is to provide a chip carrier having a smooth optical response without a dip in a band in an electro-absorption optical modulator having a traveling wave type electrode operating at a speed higher than 40 Gbit / s.
The solution is any one or a combination of the following four methods.
(1) The ground conductor on the front surface of the chip and the metal base substrate on the back surface of the chip are electrically connected in the electroabsorption type optical modulator chip.
(2) The ground conductor on the surface of the dielectric substrate on which the terminating resistor is formed and the metal base substrate are not electrically connected in the dielectric substrate.
(3) Form a terminating resistor in the electro-absorption optical modulator chip.
(4) The input high-frequency line and the high-frequency line for connecting to the terminating resistor are formed on the same side of the optical modulator chip with respect to the optical waveguide.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical transmission device, and more particularly, to an optical transmission device having an optical chip that externally modulates output light of a semiconductor laser or an output unit that couples an output of the optical chip to a transmission optical fiber. The present invention relates to an electrical mounting of an optical modulator chip carrier and a modulator driving circuit incorporated in an optical transmission device suitable for an ultra-high-speed optical communication system of 40 gigabits per second or more.
[0002]
[Prior art]
The electrode structure of an optical modulator used for optical communication is roughly classified into a lumped constant type and a traveling wave type. Among them, the lumped-constant type element has an operation speed limitation due to a so-called CR time constant (element capacitance C, element resistance R), and in order to realize a high speed, the element length is reduced to reduce C. There is a need to. For this reason, there is a limit in achieving high speed, high light resistance, and low voltage driveability at the same time.
[0003]
On the other hand, the traveling wave type element is an improved version of the lumped element type element. The electrode formed near the optical waveguide is treated as a transmission line, and the high-frequency electric signal propagates on the electrode in the form of a traveling wave. For this reason, it is possible to realize a high-speed operation that does not depend on the CR time constant (IEEE Journal of Quantum Electronics, No. 27, Third Volume, page 654, March 1991, or IEEE Electronics Letters, No. 18). 33, p. 1580, August 28, 1997). In particular, in the case of ultra-high-speed communication exceeding a modulation speed of 40 Gbit / s, an optical modulator having a traveling-wave-type electrode is considered to be essential.
[0004]
In general, as a waveguide material of a traveling wave optical modulator, lithium niobate, an InP-based compound, a GaAs-based compound semiconductor, or the like has been studied. In an optical modulator using lithium niobate as a substrate, a dielectric substrate on which a high-frequency input signal line is formed is not used because the substrate has sufficient strength. A high-frequency signal can be directly input to a high-frequency line on a substrate on which an optical modulator is formed (Japanese Patent Laid-Open No. Hei 10-221664).
[0005]
On the other hand, the semiconductor optical modulator has insufficient strength because the thickness of the substrate is as thin as 100 μm at most, and an optical modulator chip is required for inputting a high-frequency signal and connecting to a resistor for terminating the signal. Separately, it is necessary to mount a dielectric substrate on which a high-frequency signal line is formed.
[0006]
FIG. 1 shows an example of an optical modulator chip carrier configured by mounting an electro-absorption optical modulator chip having a traveling wave type electrode and a dielectric substrate on which a high-frequency signal line is formed. FIG. 1A is a top view, and FIG. 1B is a cross-sectional view along AA ′. On a metal base substrate 101, a high-frequency signal input dielectric substrate 111, an electro-absorption type optical modulator chip 131 having a traveling wave type electrode, and a termination resistance forming dielectric substrate 141 are fixed. The high-frequency signal input dielectric substrate 111 includes a center conductor 112, a ground conductor 113, and a via hole 114 formed on a dielectric substrate 115. An electro-absorption optical modulator chip 131 having a traveling-wave type electrode includes a modulator electrode 132, a ground conductor 133, an optical waveguide 134, an optical electric field absorber 135, and a high-frequency signal input formed on a semi-insulating semiconductor substrate 138. It comprises a conductor 136 and a high-frequency signal output connection conductor 137. The terminating resistor forming dielectric substrate 141 includes a center conductor 142, a ground conductor 143, a via hole 144, and a terminating resistor 145 formed on the dielectric substrate 146. The center conductors 112, 132, 142 for guiding signals and the ground conductors 113, 133, 143 are electrically connected by the gold ribbon 121, respectively. However, the center conductor and the ground conductor are insulated. I have. The signal input to the modulator electrode 132 formed on the optical electric field absorbing section 135 modulates the light propagating in the optical waveguide 134.
[0007]
When the optical response of the optical modulator chip carrier was measured, a dip was observed at a frequency of 17 GHz as shown in FIG.
[0008]
[Problems to be solved by the invention]
For example, when a signal having a modulation speed of 40 Gbit / s is transmitted, this dip causes a significant deterioration of the signal. In order to transmit a signal of 40 Gbit / s, a smooth optical response without a dip is required at least in a frequency region smaller than 40 GHz.
[0009]
Accordingly, an object of the present invention is to provide a chip carrier for an optical modulator which operates at a speed higher than 40 Gbit / s and has a smooth optical response without a dip in a band, particularly an electroabsorption optical modulator. That is. The reason why the target of the modulator is limited to the electroabsorption type will be described later.
[0010]
[Means for Solving the Problems]
We considered the cause of the dip as follows.
[0011]
The high-frequency signal line formed on the dielectric substrate in which the via hole is formed has a so-called grand coplanar structure. On the other hand, the electroabsorption optical modulator chip generally has a coplanar structure in which the ground conductor on the front surface of the chip and the base substrate on the rear surface are not electrically connected. Because of the different electrode structures, the fundamental modes of the lines of electric force generated in the respective high-frequency lines do not match. For this reason, when a high-frequency signal is input to the optical modulator chip from the high-frequency signal line formed on the dielectric substrate, the optical modulator chip includes, in addition to a normal coplanar mode (first mode) electric signal, Then, a second mode generated between the ground metal on the chip surface side and the base substrate is induced.
FIG. 3 shows a conceptual diagram of the mode of the electric flux lines of the high-frequency signal. 121 is a line of electric force. (A) is the mode of the high-frequency signal line formed on the dielectric substrate (cross section BB 'in FIG. 1), and (b) is the first mode (cross section C- in FIG. 1) generated in the semiconductor optical modulator. C ′) and (c) are the second mode (cross-section CC ′ in FIG. 1). Note that among the reference numerals in FIG. 3, the same reference numerals as those in FIG. 1 indicate the same components.
[0012]
The first mode generated in the optical modulator chip propagates along a high-frequency line formed on the surface of the optical modulator chip. On the other hand, the second mode travels straight without being affected by the high-frequency line. Then, the two modes are coupled by the dielectric substrate on which the terminating resistor is formed. At this time, the effective permittivity of the first mode is about 50, whereas the effective permittivity of the second mode is about 12, which is greatly different, so that the two modes have different propagation speeds. Therefore, at a certain frequency, the first mode and the second mode having opposite phases are combined, and a dip occurs.
[0013]
According to this principle, it is considered that a dip occurs particularly in an electroabsorption optical modulator having a modulator length as short as about 100 to 200 μm as compared with a Mach-Zehnder modulator. This is because, when the modulator length is short, the input conductor (136 in FIG. 1) on the optical modulator chip and the termination resistance connection conductor (137 in FIG. 1) face each other, and the termination resistance forming dielectric of the second mode is formed. The coupling to the high-frequency conductor 142 on the substrate (141 in FIG. 1) is strengthened. Therefore, the present invention is particularly effective when the electric absorption type optical modulator is electrically mounted.
[0014]
According to this principle, the dip is eliminated by the following three methods.
[0015]
First, the second mode is not generated. To realize this, the ground conductor on the surface and the metal base may be electrically connected in the optical modulator chip.
One example is to form a via hole in the optical modulator chip.
[0016]
Second, it does not terminate the second mode. In the conventional example shown in FIG. 1, not only the first mode but also the second mode is terminated because the dielectric substrate having the terminating resistor has a via hole. As a method of not terminating the second mode, it is conceivable that the dielectric substrate on which the terminating resistor is formed has no via hole, and that the terminating resistor is formed on the optical modulator chip. With such a configuration, the termination resistance does not exist between the ground conductor on the front surface side and the back conductor in the termination resistance portion, and the second mode is not terminated.
[0017]
Third, the second mode is not coupled to the high-frequency line connecting to the terminating resistor. Since the second mode travels straight without being affected by the high-frequency line, the terminating resistor need not be formed in the direction in which the input signal travels straight. This specific method is shown in FIG. FIG. 4A is a top view, and FIG. 4B is a cross-sectional view along AA ′. On a metal base substrate 101, an electric absorption type optical modulator chip 131 having a high frequency signal input dielectric substrate 111 and a traveling wave type electrode is fixed. It should be noted that the same reference numerals in FIG. 4 as those in FIG. 1 indicate the same components.
[0018]
The connection conductor 137 to the terminating resistor on the optical modulator chip was formed on the same side of the optical waveguide 134 as the high-frequency input conductor 136. When the optical response of the chip carrier was measured, as shown in FIG. 5, it was possible to obtain a smooth frequency characteristic without a dip in a frequency range of 50 GHz or less.
[0019]
Further, by forming the connection line to the terminating resistor on the optical modulator chip on the same side as the high-frequency input line with respect to the optical waveguide, there are the following three advantages.
[0020]
The first is in terms of chip area. Compared to the optical modulator chip 131 having the conventional structure shown in FIG. 1, the optical modulator chip 131 of the present invention shown in FIG. 4 has a chip area of about half, and the manufacturing cost is reduced to about half in proportion to the area. .
[0021]
Second, the number of dielectric substrates can be reduced. Compared with the chip carrier having the conventional structure shown in FIG. 1, the chip carrier of the present invention shown in FIG. 4 does not require the termination resistor forming dielectric substrate 141, thereby reducing the size of the chip carrier and reducing the manufacturing cost of the chip carrier. Reduction is possible.
[0022]
Third, when the optical modulator drive circuit is hybrid-mounted, the terminating resistor forming step can be omitted. FIG. 6 shows an equivalent circuit diagram of the optical modulator driving circuit 303 and the electro-absorption optical modulator 301 having a traveling wave electrode. It comprises an optical modulator 301, a connection high-frequency line 302, a modulator driving circuit 303, a terminating resistor 311, an optical modulator 312 having a traveling-wave electrode, resistors 321, 322, 323, transistors 324, 325, and a current source 326. . As shown in the figure, resistors 321, 322, and 323 are always formed in the optical modulator drive circuit. If the terminating resistor 311 for the optical modulator is formed at the same time as the formation of this resistor, it is not necessary to form the resistor 145 on the dielectric substrate shown in FIG. 4, which contributes to a reduction in manufacturing cost.
[0023]
The above description also applies to a case where a laser light source is monolithically integrated with an electroabsorption optical modulator. In particular, as shown in FIG. 7, the chip area is reduced by forming the laser electrode 802 on the same side of the optical waveguide 134 as the high-frequency input conductor 136 on the surface of the electroabsorption optical modulator.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
(Example 1)
FIG. 8 is a diagram showing a configuration of a main part of an optical transmitter according to the present invention. Specifically, it is a diagram illustrating a configuration of an optical transmission device including a laser light source 501 having a wavelength of 1.55 μm, an electro-absorption optical modulator 131 having a traveling-wave electrode, and a modulator driving circuit 601. (A) is a top view, (b) is a cross-sectional view taken along the line AA 'in FIG. (A), and (c) is a cross-sectional view of the optical electric field absorbing portion 135. In addition, the same code | symbol as FIG. 1-7 among the code | symbols in FIG. 8 shall point out the same thing. The high-frequency signal generated by the modulator drive circuit 601 is input to the optical modulator chip 131 from the high-frequency input conductor 136. The high-frequency signal reaches the optical electric field absorption unit 135, and modulates the intensity of the laser light 502 emitted from the laser light source 501 to generate a modulated light 503. Thereafter, the high-frequency signal propagates through the termination resistance connection conductor 137, passes through the gold ribbon 121, reaches the termination resistance forming dielectric substrate 141, and is terminated by the termination resistance 145. Specifically, it was formed as follows.
[0025]
An electro-absorption type optical modulator chip 131 and a terminal resistance forming high-frequency substrate 141 are fixed on a metal base substrate 101 made of copper tungsten. The electroabsorption optical modulator 131 is formed on a semi-insulating semiconductor substrate 138. On the chip surface, an optical waveguide 134, a center conductor 132 forming a high-frequency line, and a ground conductor 133 are formed. The absorption layer structure was as shown in FIG. First, 5 × 10 5 on a semi-insulating InP substrate 138 doped with iron. ¹⁸ / Cm ^-3 The InP layer 703 doped with Si at a concentration of 2.5 μm is stacked thereon, and a multiple quantum well layer 702 made of InGaAsP is grown to a thickness of 0.23 μm on both the well layer and the barrier layer. On this, a p-InP cladding layer 701 was grown by 1.7 μm. The doping level of this layer is 2 × 10 ¹⁷ ~ 8 × 10 ¹⁸ cm ^-3 8 × 10 on a 0.7 μm layer changed to ¹⁸ cm ^-3 Is an InGaAs layer having a thickness of 0.9 μm and 0.2 μm, and the doping concentration is 1 × 10 ¹⁹ cm ^-3 Concentration. A mesa stripe serving as an optical waveguide was formed on such a multilayer substrate, and portions other than the waveguide were formed as a polyimide layer 704 for flattening and capacity reduction. The width of the mesa stripe was 1.6 μm and the height was 2.2 μm. Gold having a width of 4 μm and a thickness of 850 nm was deposited on the conductor 132 constituting the transmission line disposed thereon. The ground conductor 133 was formed by depositing gold with a thickness of 300 nm. The distance between the center conductor 132 and the ground conductor 133 was 12 μm. The termination resistor forming dielectric substrate 141 is formed on the aluminum nitride 146 from a center conductor 142 and a ground conductor 143 formed of a multilayer film of Ti, Mo, Ni, and gold. Further, in order to stabilize the potential of the ground conductor 143 on the substrate surface, four via holes 144 are formed and are electrically connected to the metal base substrate 101. The ground conductor 133 in the electroabsorption type optical modulator chip 131 and the ground conductor 143 in the termination resistance forming high frequency substrate 141, and the center conductor 132 in the electroabsorption type optical modulator chip 131 and the center in the termination resistance forming high frequency substrate 141 The conductors 142 are electrically connected by a gold ribbon 121 having a width of 50 μm. The optical modulator drive circuit is formed on a semi-insulating InP substrate 605 and is composed of a hetero bipolar transistor.
[0026]
In the optical modulator chip, a total of four via holes 139 were formed in the high-frequency input conductor 136 and the ground conductor 133 near the terminating resistor connection conductor 137.
[0027]
As a result, a 3 dB attenuation frequency band of 40 GHz of the optical response was achieved, and a good optical response with no dip at a frequency of 50 GHz or less was obtained.
[0028]
Although an example in which polyimide is flattened as the waveguide structure has been described above, a similar effect can be obtained by using a buried structure using a semiconductor. In addition, although InP is used as the substrate, a GaAs substrate may be used. Although the InGaAsP multiple quantum well has been described as the absorption layer of the optical modulator, it may be an InGaAlAs multiple quantum well. The wavelength of the laser beam is 1.55 μm, but may be in the range of 1.3 μm to 1.6 μm.
(Example 2)
FIG. 9 is a diagram showing a configuration of a main part of an optical transmitter according to the present invention. Specifically, FIG. 2 is a diagram illustrating a configuration of an optical transmission device including a laser light source 501 having a wavelength of 1.55 μm, an electro-absorption optical modulator 131, and a modulator driving circuit 601. The same reference numerals in FIG. 9 as those in FIG. 1-8 indicate the same components.
[0029]
This embodiment is almost the same as the first embodiment, except that no via hole is formed in the electro-absorption optical modulator 131 and the termination-resistance-formed dielectric substrate 141.
[0030]
As a result, a 3 dB attenuation frequency band of 40 GHz of the optical response was achieved, and a good optical response with no dip at a frequency of 50 GHz or less was obtained.
(Example 3)
FIG. 10 is a diagram showing a configuration of a main part of an optical transmitter according to the present invention. Specifically, FIG. 2 is a diagram illustrating a configuration of an optical transmission device including a laser light source 501 having a wavelength of 1.55 μm, an electro-absorption optical modulator 131, and a modulator driving circuit 601. Note that the same reference numerals in FIG. 10 as those in FIG. 1-9 indicate the same components. The high-frequency signal generated by the modulator driving circuit 601 is input to the optical modulator chip 131 from the high-frequency input line 136. The high-frequency signal reaches the optical electric field absorption unit 135, and modulates the intensity of the laser light 502 emitted from the laser light source 501 to generate a modulated light 503. Thereafter, the high-frequency signal propagates through the terminating resistor connection line 137 and is terminated by the terminating resistor 140 formed on the optical modulator chip. Specifically, it was formed as follows.
[0031]
An electro-absorption type optical modulator chip 131 is fixed on a metal base substrate 101 made of copper tungsten. The configuration of the electro-absorption optical modulator chip 131 is the same as that of the first embodiment except that a terminating resistor 145 is formed on the chip. The terminating resistor 145 has a total resistance value of 50Ω by connecting the center conductor 132 and the ground conductors 133 formed on both sides with 100Ω silicon-nitride-tungsten, respectively. Other forms of the optical modulator chip 131 are the same as those of the method shown in the first embodiment.
[0032]
As a result, a 3 dB attenuation frequency band of 40 GHz of the optical response was achieved, and a good optical response with no dip at a frequency of 50 GHz or less was obtained.
[0033]
FIG. 10 shows an example in which the via hole 139 is formed in the optical modulator chip 131, but the same result is obtained even when there is no via hole.
(Example 4)
FIG. 11 is a diagram showing a configuration of a main part of an optical transmitter according to the present invention. Specifically, FIG. 2 is a diagram illustrating a configuration of an optical transmission device including a laser light source 501 having a wavelength of 1.55 μm, an electro-absorption optical modulator 131, and a modulator driving circuit 601. The same reference numerals in FIG. 11 as those in FIG. 1-10 indicate the same components. This is almost the same as the first embodiment, except that the high-frequency input line 136 and the terminating resistor connection line 137 of the electroabsorption optical modulator 131 are formed on the same side with respect to the optical waveguide 134. The high-frequency signal generated by the modulator drive circuit 601 is input from the modulator drive signal output unit 602 to the high-frequency input line 136. The high-frequency signal reaches the optical electric field absorption unit 135, and modulates the intensity of the laser light 502 emitted from the laser light source 501 to generate a modulated light 503. Thereafter, the high-frequency signal propagates through the terminating resistor connection line 137, reaches the terminating resistor 603 formed on the optical modulator driving circuit, and is terminated.
[0034]
The optical modulator chip 131 has the same form as that of the first embodiment except that the electrode structure and the via hole 139 are not provided. The main difference from the first embodiment is that the high-frequency input line 136 and the terminal resistance connection line 137 of the electroabsorption optical modulator 131 are formed on the same side with respect to the optical waveguide 134.
[0035]
As a result, a 3 dB attenuation frequency band of 40 GHz of the optical response was achieved, and a good optical response with no dip at a frequency of 50 GHz or less was obtained.
[0036]
FIG. 11 shows an example in which a via hole is not formed in the optical modulator chip 131, but the same result is obtained when a via hole is formed. Further, although the example in which the terminating resistor is formed in the optical modulator driving circuit has been described, it may be formed in the optical modulator chip 131.
(Example 5)
FIG. 12 is a diagram showing a configuration of a main part of an optical transmitter according to the present invention. Specifically, the figure shows the configuration of an optical transmission device including a laser light source 501 having a wavelength of 1.55 μm, an electro-absorption optical modulator 131, a high-frequency signal input dielectric substrate 111, and a modulator driving circuit 601. is there. Note that the same reference numerals in FIG. 12 as those in FIG. 1-11 indicate the same components. The difference from the fourth embodiment is that a high frequency signal input dielectric substrate 111 is inserted between the electro-absorption optical modulator 131 and the optical modulator driving circuit 601. As a result, it is possible to minimize the influence of the heat generated in the optical modulator driving circuit 601 on the optical modulator characteristics.
[0037]
The characteristic impedance of the high-frequency line of the dielectric substrate 111 is 50Ω, which is the same as that of the optical modulator drive circuit. Specifically, the thickness of the dielectric substrate 115 was 250 μm, the width of the center conductor 112 was 90 μm, and the distance between the center conductor 112 and the ground conductor 113 was 34 μm.
[0038]
As a result, a 3 dB attenuation frequency band of 40 GHz of the optical response was achieved, and a good optical response with no dip at a frequency of 50 GHz or less was obtained.
[0039]
Although the characteristic impedances of the optical modulator drive circuit and the high-frequency line of the dielectric substrate 111 are set to 50Ω, they need only match and are not limited to 50Ω.
(Example 6)
FIG. 13 is a diagram showing a configuration of a main part of an optical transmitter according to the present invention. Specifically, the figure shows the configuration of an optical transmission device including a laser light source 501 having a wavelength of 1.55 μm, an electro-absorption optical modulator 131, a high-frequency signal input dielectric substrate 111, and a modulator driving circuit 601. is there. In addition, the same code | symbol as FIG. 1-12 among the code | symbols in FIG. 13 shall point out the same thing.
[0040]
A high-impedance line section 117 having a characteristic impedance of 99.2 Ω is provided on a part of the dielectric substrate 111. Specifically, the width of the center conductor was 16 μm, the distance between the center conductor and the ground conductor was 71 μm, and the length was 150 μm. Other aspects are the same as the fifth embodiment.
[0041]
The reason why the high-frequency line having the characteristic impedance of 99.2Ω is provided will be described. The characteristic impedance of the optical modulator unit having the current structure is 25Ω, and when it is connected to a commonly used 50Ω system, an electric high-frequency signal is reflected, which causes deterioration of a modulation waveform. If a line having a higher impedance than 50Ω is provided on both sides of the optical modulator section in the traveling wave type electrode, the impedance of the structure connected to the high impedance line, the light modulation section and the high impedance line becomes 50Ω on average, and the electric high frequency signal Is suppressed.
[0042]
As a result, a 3 dB attenuation frequency band of 40 GHz of the optical response was achieved, and a good optical response with no dip at a frequency of 50 GHz or less was obtained. Further, the electric reflection coefficient S11 at a frequency of 20 GHz achieved −20 dB.
(Example 7)
FIG. 14 is a diagram showing a configuration of a main part of an optical transmitter according to the present invention. Specifically, the figure shows the configuration of an optical transmission device including a laser light source 501 having a wavelength of 1.55 μm, an electro-absorption optical modulator 131, a high-frequency signal input dielectric substrate 111, and a modulator driving circuit 601. is there. The same reference numerals as those in FIGS. 1 to 13 among the reference numerals in FIG. 14 indicate the same components. The difference from the fifth embodiment is that the terminating resistor 603 is formed on the high frequency input signal dielectric substrate 111.
[0043]
As a result, a 3 dB attenuation frequency band of 40 GHz of the optical response was achieved, and a good optical response with no dip at a frequency of 50 GHz or less was obtained.
[0044]
Further, by inserting a line having an impedance higher than 50Ω in the middle of the input and output lines on the high-frequency signal input dielectric substrate 111, the electric reflection characteristics can be improved.
(Example 8)
FIG. 15 is a diagram showing a configuration of a main part of the optical transmission device according to the present invention. More specifically, FIG. 4 is a diagram showing a configuration of an optical transmission device including a laser light source 501 having a wavelength of 1.55 μm, an electro-absorption optical modulator 131, a high-frequency signal input dielectric substrate 111, and a modulator driving circuit 601. is there. In addition, the same code | symbol as FIG. 1-14 among the code | symbols in FIG. 15 shall point out the same thing. The difference from the fourth embodiment is that the laser 801 is monolithically integrated in the electro-absorption optical modulator 131. By monolithically integrating the laser, the size of the optical transmission device can be reduced.
[0045]
The laser current is supplied from a laser power supply 805 to a laser electrode 802 via a chip capacitor 804 and a ribbon bonding 803.
[0046]
As a result, a 3 dB attenuation frequency band of 40 GHz of the optical response was achieved, and a good optical response with no dip at a frequency of 50 GHz or less was obtained.
[0047]
It is needless to say that this embodiment in which the laser is integrated is applicable to the electroabsorption optical modulator chip 131 of the embodiment 1-7.
[0048]
Further, the contact point between the bonding wire 803 for the laser electrode and the laser electrode 802 on the chip is on the same side as the high-frequency input line 136 with respect to the optical waveguide 134, so that the electric absorption type optical modulator chip 131 Further miniaturization is achieved.
Note:
1. An electroabsorption optical modulator, a traveling-wave electrode provided on a part of an optical waveguide constituting a part of the optical modulator, a first high-frequency signal input line, and a first high-frequency signal output line And a first substrate provided on the surface thereof,
The modulator is for modulating output light from a laser light source, the output of a modulator drive circuit is connected to the first high-frequency signal input line,
When the first substrate is divided into first and second sides by the linear optical waveguide, the first high-frequency signal input line, the first high-frequency signal output line, and the terminating resistor are provided on the first side. Wherein the first high-frequency signal input line, the first high-frequency signal output line, and the terminating resistor are electrically connected through the electrode.
2. 2. The light according to claim 1, wherein a geometric shape of a signal path passing through the first high-frequency signal input line, the electrode, the first high-frequency signal output line, and the terminating resistor is U-shaped. Transmission device.
3. 2. The optical transmitter according to claim 1, wherein the semiconductor laser light source and the modulator are monolithically integrated on the first substrate.
4. The optical transmission device according to claim 3, wherein an electrical contact of the laser light source is disposed on the first side.
5. A first dielectric substrate having a second high-frequency signal input line provided on a surface thereof; an electroabsorption type optical modulator; and a light guide provided on a part of an optical waveguide constituting a part of the optical modulator. A first substrate having a corrugated electrode provided on its surface, a first dielectric substrate and a metal base having the first substrate provided on its surface,
The modulator is for modulating output light from a laser light source, the second high-frequency signal input line is connected to an output of a modulator driving circuit,
A terminating resistor is electrically connected to the electrode via a first high-frequency signal output line electrically connected to the electrode, whereby the high-frequency signal passing through the electrode on the optical waveguide is terminated at the terminal. Configured to terminate with a resistor,
The first high-frequency signal input line is provided on a surface of the first dielectric substrate having a rectangular shape in a straight line from a first side of the first dielectric substrate to a third side facing the first dielectric substrate. ,
The optical waveguide is provided in a straight line from the second side on the first substrate, the planar shape of which is rectangular, to a fourth side opposed thereto, and provided on a part of the optical waveguide. A first high-frequency signal input line is provided on the first substrate to establish electrical connection between one end of the electrode and the second high-frequency signal input line; A first high-frequency signal output line is provided on the first substrate for making electrical connection with the terminating resistor;
A ground conductor is provided around the first high-frequency signal input line and the first high-frequency signal output line, and the first high-frequency signal input line and the first high-frequency signal output line are connected to the ground conductor. Means for electrically connecting the ground conductor and the metal base substrate are provided,
The optical transmission device, wherein the first and second high-frequency signal input lines, the electrode, and the first high-frequency signal output line are electrically connected.
6. The optical transmission device according to claim 5, wherein the means is a via hole.
7. The optical transmission device according to claim 5, wherein the terminating resistor is provided on the first substrate.
8. When the first substrate is divided into the first and second sides by the linear optical waveguide, the first high-frequency signal input line and the terminating resistor are arranged on the first side. The optical transmission device according to claim 7, wherein:
9. When the first substrate is divided into the first and second sides by the optical waveguide in the straight line, the first high-frequency signal input line and the terminating resistor are arranged on the first side. The optical transmission device according to claim 5, wherein:
10. The optical transmission device according to claim 9, wherein the terminating resistor is provided on the first substrate.
11. The optical transmission device according to claim 9, wherein the terminating resistor is provided on the first dielectric substrate.
12. The optical transmitter according to claim 5, wherein the semiconductor laser light source and the modulator are monolithically integrated on the first substrate.
13. When the first substrate is divided into first and second sides by the optical waveguide from the laser light source to the optical modulator, an electric contact of the laser light source and the first high-frequency wave are provided on the first side. 13. The optical transmission device according to claim 12, wherein a signal input line is arranged.
14． A first dielectric substrate having a second high-frequency signal input line provided on a surface thereof; an electroabsorption type optical modulator; and a light guide provided on a part of an optical waveguide constituting a part of the optical modulator. A first substrate having a corrugated electrode provided on the surface thereof; and a second dielectric member having a second high-frequency signal output line provided on the surface thereof and a terminating resistor provided at one end of the line. A substrate, a metal base having the first dielectric substrate, the first substrate, and the second dielectric substrate provided on a surface thereof;
The modulator is for modulating output light from a laser light source, the second high-frequency signal input line is connected to an output of a modulator driving circuit,
A terminating resistor is electrically connected to the electrode via a first high-frequency signal output line and the second high-frequency signal output line electrically connected to the electrode. The high-frequency signal passing through the electrode is configured to be terminated by the terminating resistor,
The second high-frequency signal input line is provided on the surface of the first dielectric substrate having a rectangular shape in a straight line from a first side to a third side opposite to the first dielectric substrate. ,
The optical waveguide is provided in a linear shape from a second side on the first substrate, the planar shape of which is rectangular, to a fourth side opposed thereto,
A first high-frequency signal input line is provided on the first substrate for establishing electrical connection between one end of the electrode and the second high-frequency signal input line;
The second high-frequency signal input line is provided on a surface of the second dielectric substrate having a rectangular shape in a straight line from a first side to a third side opposite to the second dielectric substrate. ,
The first high-frequency signal output line is provided on the first substrate, the second high-frequency signal output line is provided between the first high-frequency signal output line and the terminating resistor,
A ground conductor is provided around the second high-frequency signal output line, the second high-frequency signal output line is electrically insulated from the ground conductor, and the metal base and the second dielectric substrate are provided. Is electrically insulated between
The optical transmission device, wherein the first and second high-frequency signal input lines, the electrodes, and the first and second high-frequency signal output lines are electrically connected.
15. The optical transmitter according to claim 14, wherein the semiconductor laser light source and the modulator are monolithically integrated on the first substrate.
16. A first dielectric substrate having a second high-frequency signal input line provided on a surface thereof, an electro-absorption optical modulator,
A traveling-wave-type electrode provided on a part of an optical waveguide constituting a part of the optical modulator, and a first substrate provided on a surface thereof;
The modulator is for modulating output light from a laser light source, the second high-frequency signal input line is connected to an output of a modulator driving circuit,
By providing a first high-frequency signal output line for electrically connecting between the electrode and the terminating resistor provided on the first substrate, the electrode has passed the electrode. A high-frequency signal is configured to terminate at the terminating resistor,
The first high-frequency signal input line is provided on a surface of the first dielectric substrate having a rectangular shape in a straight line from a first side of the first dielectric substrate to a third side facing the first dielectric substrate. ,
The optical waveguide is provided in a linear shape from a second side on the first substrate, the planar shape of which is rectangular, to a fourth side opposed thereto,
A second high-frequency signal input line is provided on the first substrate for establishing electrical connection between one end of the electrode and the first high-frequency signal input line;
The optical transmission device, wherein the first high-frequency signal output line and the terminating resistor are provided on the first substrate.
17. 17. The optical transmitter according to claim 16, wherein the semiconductor laser light source and the modulator are monolithically integrated on the first substrate.
[0049]
【The invention's effect】
According to the present invention, it is possible to provide an electro-absorption optical modulator chip carrier having a good frequency response, which enables transmission at a transmission rate of 40 Gbit / s or more. At the same time, the number of dielectric substrates can be reduced, the chip size can be reduced, and the terminating resistor forming process can be omitted.
[Brief description of the drawings]
FIG. 1 is a chip carrier diagram of a conventional electro-absorption optical modulator having a traveling-wave electrode. (A) Plan view (b) Sectional view along the AA 'line shown in the plan view.
FIG. 2 shows an example of an optical response measured by the conventional chip carrier shown in FIG.
FIG. 3 is a conceptual diagram of a mode of an electric flux line of a high-frequency signal. (A) Mode of high-frequency signal line formed on dielectric substrate (cross section BB 'in FIG. 1) (b) First mode generated in semiconductor optical modulator (cross section CC' in FIG. 1) (C) Second mode (cross-section CC ′ in FIG. 1).
FIG. 4 shows a chip carrier configuration according to the present invention. (A) Top view (b) Sectional drawing along the AA 'line shown in the plan view.
FIG. 5 is an example of an optical response measured by the chip carrier of the present invention shown in FIG.
FIG. 6 is an equivalent circuit diagram of an optical modulator driving circuit and an electro-absorption optical modulator having a traveling wave electrode.
FIG. 7 is a top view of an optical modulator chip in which a laser is monolithically integrated according to the present invention.
FIG. 8 shows an embodiment of the optical transmission device according to the present invention. (A) Top view (b) Cross-sectional view along line AA 'shown in top view (c) Cross-sectional view along line DD' shown in top view, enlarged optical waveguide portion .
FIG. 9 shows an embodiment of an optical transmission device according to the present invention.
FIG. 10 shows an embodiment of an optical transmission device according to the present invention.
FIG. 11 shows an embodiment of an optical transmission device according to the present invention.
FIG. 12 shows an embodiment of an optical transmission device according to the present invention.
FIG. 13 shows an embodiment of the optical transmission device according to the present invention.
FIG. 14 shows an embodiment of the optical transmission device according to the present invention.
FIG. 15 shows an embodiment of the optical transmission device according to the present invention.
[Explanation of symbols]
101 {metal base substrate, 111} dielectric substrate for high frequency signal input, 112} center conductor, 113} ground conductor, 114 via hole, 115 dielectric substrate, 116 termination resistance, 117 high impedance line section, 121} Gold ribbon, 131 ‥ electroabsorption type optical modulator chip, 132 ‥ modulator electrode, 133 ‥ ground conductor, 134 ‥ optical waveguide, 135 ‥ optical electric absorption part, 136 ‥ high-frequency signal input conductor, 137 ‥ high-frequency signal output connection conductor 138 semi-insulating semiconductor substrate, 139 via hole, 140 termination resistor, 141 termination dielectric substrate, 142 center conductor, 143 ground conductor, 144 via hole, 145 termination resistor, 146 dielectric Board, 147 ‥ Terminal resistor connection center conductor,
201 ‥ line of electric force,
301 optical modulator, 302 connected high-frequency line, 303 modulator driving circuit, 311 terminating resistor, 312 optical modulator having traveling-wave type electrode, 321,322,323 resistor, 324,325 transistor, 326 ° current source,
401 ‥ laser electrode,
501 ° laser light source, 502 ° laser light, 503 ° modulated light,
601 modulator drive circuit, 602 modulator drive signal output unit, 603 termination resistor, 604 base substrate for optical modulator drive circuit, 605 semi-insulating semiconductor substrate,
701 ‥ pInP cladding layer, 702 ‥ MQW layer, 703 ‥ n-InP layer, 704 ‥ polyimide layer,
801 laser, 802 laser electrode, 803 bonding wire for laser electrode, 804 chip capacitor, 805 laser current source.

Claims (15)

An electroabsorption optical modulator, a traveling-wave electrode provided on a part of an optical waveguide constituting a part of the optical modulator, a first high-frequency signal input line, and a first high-frequency signal output line And a first substrate provided on the surface thereof,
The modulator is for modulating output light from a laser light source, the output of a modulator drive circuit is connected to the first high-frequency signal input line,
When the first substrate is divided into first and second sides by the linear optical waveguide, the first high-frequency signal input line, the first high-frequency signal output line, and the terminating resistor are provided on the first side. Wherein the first high-frequency signal input line, the first high-frequency signal output line, and the terminating resistor are electrically connected through the electrode. 2. The light according to claim 1, wherein a geometric shape of a signal path passing through the first high-frequency signal input line, the electrode, the first high-frequency signal output line, and the terminating resistor is U-shaped. Transmission device. 2. The optical transmitter according to claim 1, wherein the semiconductor laser light source and the modulator are monolithically integrated on the first substrate. The optical transmission device according to claim 3, wherein an electrical contact of the laser light source is disposed on the first side. A first dielectric substrate having a second high-frequency signal input line provided on a surface thereof; an electroabsorption type optical modulator; and a light guide provided on a part of an optical waveguide constituting a part of the optical modulator. A first substrate having a corrugated electrode provided on its surface, a first dielectric substrate and a metal base having the first substrate provided on its surface,
The modulator is for modulating output light from a laser light source, the second high-frequency signal input line is connected to an output of a modulator driving circuit,
A terminating resistor is electrically connected to the electrode via a first high-frequency signal output line electrically connected to the electrode, whereby the high-frequency signal passing through the electrode on the optical waveguide is terminated at the terminal. Configured to terminate with a resistor,
The first high-frequency signal input line is provided on a surface of the first dielectric substrate having a rectangular shape in a straight line from a first side of the first dielectric substrate to a third side facing the first dielectric substrate. ,
The optical waveguide is provided in a straight line from the second side on the first substrate, the planar shape of which is rectangular, to a fourth side opposed thereto, and provided on a part of the optical waveguide. A first high-frequency signal input line is provided on the first substrate to establish electrical connection between one end of the electrode and the second high-frequency signal input line; A first high-frequency signal output line is provided on the first substrate for making electrical connection with the terminating resistor;
A ground conductor is provided around the first high-frequency signal input line and the first high-frequency signal output line, and the first high-frequency signal input line and the first high-frequency signal output line are connected to the ground conductor. Means for electrically connecting the ground conductor and the metal base substrate are provided,
The optical transmission device, wherein the first and second high-frequency signal input lines, the electrode, and the first high-frequency signal output line are electrically connected. The optical transmission device according to claim 5, wherein the means is a via hole. The optical transmission device according to claim 5, wherein the terminating resistor is provided on the first substrate. When the first substrate is divided into the first and second sides by the linear optical waveguide, the first high-frequency signal input line and the terminating resistor are arranged on the first side. The optical transmission device according to claim 7, wherein: When the first substrate is divided into the first and second sides by the optical waveguide in the straight line, the first high-frequency signal input line and the terminating resistor are arranged on the first side. The optical transmission device according to claim 5, wherein: The optical transmission device according to claim 9, wherein the terminating resistor is provided on the first substrate. The optical transmission device according to claim 9, wherein the terminating resistor is provided on the first dielectric substrate. The optical transmitter according to claim 5, wherein the semiconductor laser light source and the modulator are monolithically integrated on the first substrate. When the first substrate is divided into first and second sides by the optical waveguide from the laser light source to the optical modulator, an electric contact of the laser light source and the first high-frequency wave are provided on the first side. 13. The optical transmission device according to claim 12, wherein a signal input line is arranged. A first dielectric substrate having a second high-frequency signal input line provided on a surface thereof; an electroabsorption type optical modulator; and a light guide provided on a part of an optical waveguide constituting a part of the optical modulator. A first substrate having a corrugated electrode provided on the surface thereof; and a second dielectric member having a second high-frequency signal output line provided on the surface thereof and a terminating resistor provided at one end of the line. A substrate, a metal base having the first dielectric substrate, the first substrate, and the second dielectric substrate provided on a surface thereof;
The modulator is for modulating output light from a laser light source, the second high-frequency signal input line is connected to an output of a modulator driving circuit,
A terminating resistor is electrically connected to the electrode via a first high-frequency signal output line and the second high-frequency signal output line electrically connected to the electrode. The high-frequency signal passing through the electrode is configured to be terminated by the terminating resistor,
The second high-frequency signal input line is provided on the surface of the first dielectric substrate having a rectangular shape in a straight line from a first side to a third side opposite to the first dielectric substrate. ,
The optical waveguide is provided in a linear shape from a second side on the first substrate, the planar shape of which is rectangular, to a fourth side opposed thereto,
A first high-frequency signal input line is provided on the first substrate for establishing electrical connection between one end of the electrode and the second high-frequency signal input line;
The second high-frequency signal input line is provided on a surface of the second dielectric substrate having a rectangular shape in a straight line from a first side to a third side opposite to the second dielectric substrate. ,
The first high-frequency signal output line is provided on the first substrate, the second high-frequency signal output line is provided between the first high-frequency signal output line and the terminating resistor,
A ground conductor is provided around the second high-frequency signal output line, the second high-frequency signal output line is electrically insulated from the ground conductor, and the metal base and the second dielectric substrate are provided. Is electrically insulated between
The optical transmission device, wherein the first and second high-frequency signal input lines, the electrodes, and the first and second high-frequency signal output lines are electrically connected. The optical transmitter according to claim 14, wherein the semiconductor laser light source and the modulator are monolithically integrated on the first substrate.

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