Optical device, light transmitter, and light receiver

Abstract

To provide an optical device which can secure reliability of conduction on a heater electrode.SOLUTION: The optical device includes: a heater electrode on a substrate; an electrode for conduction with the heater electrode; and a plurality of penetration electrodes connecting between the heater electrode and the electrode. The heater electrode includes: a first region; and a second region connected to the first region, the second region being narrower than the first region. The penetration electrode is formed between the first region and the electrode, and a longer side of the penetration electrode closest to the second region of the penetration electrodes faces the second region.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical device, an optical transmitter, and an optical receiver.

Background Art

[0002] Optical devices such as a phase shifter in an optical modulator element of an optical transmitter used for high-speed optical communication and a photodetector in a photoreceiver element of a photoreceiver are incorporated. For example, the phase shifter, for example, raises the temperature in the optical waveguide by heater heat, the refractive index in the optical waveguide changes due to the temperature rise, and the phase of the signal light passing through the optical waveguide is shifted according to the change in the refractive index.

[0003] FIG. 12 is a schematic plan view showing an example of a conventional phase shifter 200, and FIG. 13 is a schematic cross-sectional view taken along line A-A shown in FIG. 12. The phase shifter 200 shown in FIG. 12 includes an Si substrate 211, a cladding layer 212, an optical waveguide 201, a heater electrode 202, an electrode 203, and a via 204. The cladding layer 212 is laminated on the Si substrate 211 and surrounds the periphery of the optical waveguide 201 disposed on the Si substrate 211 and the periphery of the heater electrode 202 disposed on the optical waveguide 201.

[0004] The cladding layer 212 is a dielectric formed of a material having a lower refractive index than Si (silicon) of the optical waveguide 201, for example, SiO2 (silicon dioxide). The optical waveguide 201 is formed of, for example, Si and is a waveguide such as a channel-type waveguide through which signal light passes. The heater electrode 202 is formed of a resistive metal such as TiN (titanium nitride) or Ti (titanium), generates heater heat according to a drive current, and raises the temperature in the optical waveguide 201. The electrode 203 has an input-side electrode for inputting current to the heater electrode 202 by applying a voltage and an output-side electrode for outputting current from the heater electrode 202. The electrode 203 is formed of a metal having a low resistance value such as Al (aluminum) or Cu (copper). The via 204 electrically connects between the heater electrode 202 and the electrode 203. The via 204 is formed of a metal such as tungsten.

[0005] When a voltage is applied to the electrode 203, a current flows through the heater electrode 202 in the phase shifter 200, generating heater heat, which raises the temperature of the optical waveguide 201. As the temperature of the optical waveguide 201 rises, the refractive index in the optical waveguide 201 changes due to the thermo-optical effect of the Si forming the optical waveguide 201. Furthermore, the phase shifter 200 shifts the phase of the signal light passing through the optical waveguide 201 according to the change in the refractive index in the optical waveguide 201.

[0006] Since the phase shifter 200 narrows the electrode width of the heater electrode 202, the heater heat generated at the heater electrode 202 can locally heat the portion of the optical waveguide 201. As a result, the power consumption of the phase shifter 200 can be suppressed.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] In the conventional phase shifter 200, a current flows from a wide via 204 as viewed from the plane to the elongated heater electrode 202. However, in the conventional phase shifter 200, since there is only one via 204 that electrically connects the heater electrode 202 and the electrode 203, when the via 204 is disconnected, the heater electrode 202 cannot be energized, and reliability cannot be ensured.

[0009] On one side, an object is to provide an optical device or the like that can ensure the reliability of energization to the heater electrode.

Means for Solving the Problems

[0010] One aspect of the optical device includes a heater electrode formed on a substrate, an electrode for energizing the heater electrode, and a plurality of through electrodes connecting between the heater electrode and the electrode. The heater electrode has a first region and a second region that is connected to the first region and has a narrower width compared to the first region. The through electrodes are formed between the first region and the electrode, and among the plurality of through electrodes, the long side of the through electrode closest to the second region is arranged to face the second region side.

Advantages of the Invention

[0011] According to one aspect, the reliability of energization to the heater electrode can be ensured.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

DETAILED DESCRIPTION OF THE INVENTION

[0013] <Comparative Example> Therefore, a phase shifter having a plurality of vias between a heater electrode and an electrode will be described as a comparative example in order to ensure the reliability of energization to the heater electrode. FIG. 10 is a schematic plan view showing an example of a phase shifter 100 of the comparative example, and FIG. 11 is a schematic cross-sectional view taken along line A-A shown in FIG. 10. The phase shifter 100 shown in FIG. 10 includes an Si substrate 111, a cladding layer 112, an optical waveguide 102, a heater electrode 103, an electrode 104, and a via 105. The cladding layer 112 is laminated on the Si substrate 111 and surrounds the periphery of the optical waveguide 102 disposed on the Si substrate 111 and the periphery of the heater electrode 103 disposed on or near the optical waveguide 102.

[0014] The cladding layer 112 is a dielectric formed of a material having a lower refractive index than that of the Si of the optical waveguide 102, for example, SiO2 (silicon dioxide). The optical waveguide 102 is a waveguide such as a channel-type waveguide formed of, for example, Si (silicon) through which signal light passes. The heater electrode 103 is formed of a resistive metal such as TiN (titanium nitride) or Ti (titanium), generates heater heat according to a drive current, and raises the temperature in the optical waveguide 2. The electrode 104 has an input-side electrode for applying a voltage to input a current to the heater electrode 103 and an output-side electrode for outputting a current from the heater electrode 103. The electrode 104 is formed of a metal having a low resistivity such as Al (aluminum) or Cu (copper). The resistivity of the heater electrode 103 is made larger than the resistivity of the electrode 104. The via 105 electrically connects the heater electrode 103 and the electrode 104. The via 105 is formed of a metal such as tungsten.

[0015] The heater electrode 103 has two wide connection parts 103A with a wide electrode width at the connection part connected to the via 105, and a main body 103B that connects the connection parts 103A on both sides and has a narrow electrode width.

[0016] The via 105 has a planar shape with a plurality of, for example, nine rectangular small vias 105A. Each small via 105A electrically connects between the connection part 103A of the heater electrode 103 and the electrode 104. The small vias 105A include a small via 105A1 closest to the main body 103B of the heater electrode 103 and small vias 105A2 other than the small via 105A.

[0017] In the phase shifter 100 of the comparative example, when a voltage is applied to the electrode 104, a current flows through the heater electrode 103, generating heater heat, and this heater heat raises the temperature of the optical waveguide 102. When the temperature of the optical waveguide 102 rises, the refractive index in the optical waveguide 102 changes due to the thermo - optical effect of the Si forming the optical waveguide 102. Further, the phase shifter 100 shifts the phase of the signal light passing through the optical waveguide 102 according to the change in the refractive index in the optical waveguide 102.

[0018] A plurality of small vias 105A are arranged at the connection part 103A of the heater electrode 103. As a result, even if one small via 105A is disconnected, since other small vias 105A exist, the energization to the heater electrode 103 is not interrupted, and the reliability to ensure the energization operation can be secured.

[0019] In the phase shifter 100, nine small vias 105A are provided at the wide connection parts 103A at both ends of the heater electrode 103, but the resistivity of the heater electrode 103 is larger than the resistivity of the electrode 103. As a result, current concentrates on one small via 105A1 close to the main body 103B of the thin heater electrode 103, and that part is locally heated, which may affect the long - term reliability of the heater electrode 103.

[0020] Therefore, there is a demand for an optical device such as a phase shifter that can ensure reliability to guarantee the energization operation even when a disconnection occurs while suppressing current concentration. Therefore, embodiments of a phase shifter that can handle such a situation will be described below as Example 1. Note that the present invention is not limited by this embodiment. Also, each embodiment may be appropriately combined within a range that does not cause contradictions.

Example

[0021] FIG. 1 is a schematic plan view showing an example of the phase shifter 1 of Example 1, and FIG. 2 is a schematic cross-sectional view taken along line A-A shown in FIG. 1. The phase shifter 1 shown in FIG. 1 includes an Si substrate 11, a cladding layer 12, an optical waveguide 2, a heater electrode 3, an electrode 4, and a via 5. The cladding layer 12 is laminated on the Si substrate 11 and surrounds the periphery of the optical waveguide 2 disposed on the Si substrate 11 and the periphery of the heater electrode 3 disposed on or near the optical waveguide 2.

[0022] The cladding layer 12 is a dielectric formed of a material having a lower refractive index than Si of the optical waveguide 2, for example, SiO2 (silicon dioxide). The optical waveguide 2 is formed of, for example, Si (silicon) and is a waveguide such as a channel-type waveguide through which signal light passes. The heater electrode 3 is formed of a resistive metal such as TiN (titanium nitride) or Ti (titanium), generates heater heat according to the drive current, and raises the temperature in the optical waveguide 2. The electrode 4 has an input-side electrode for applying a voltage to input current to the heater electrode 3 and an output-side electrode for outputting current from the heater electrode 3, and is an electrode for energizing the heater electrode 3. The electrode 4 is formed of a metal having a low resistance value such as Al (aluminum) or Cu (copper). The via 5 is a through electrode that electrically connects the heater electrode 3 and the electrode 4. The via 5 is formed of a metal such as tungsten. The conductivity of the heater electrode 3 is made smaller than that of the via 5. The conductivity of the electrode 4 is made larger than that of the heater electrode 3.

[0023] When a voltage is applied to the electrode 4, a current flows through the heater electrode 3 in the phase shifter 1, generating heater heat, which raises the temperature of the optical waveguide 2. When the temperature of the optical waveguide 2 rises, the refractive index in the optical waveguide 2 changes due to the thermo - optical effect of the Si forming the optical waveguide 2. Further, the phase shifter 1 shifts the phase of the signal light passing through the optical waveguide 2 according to the change in the refractive index in the optical waveguide 2.

[0024] The heater electrode 3 has two connection parts 3A which are the first regions where the electrode width is wide at the connection points connecting to the via 5, and a main body 3B which connects the connection parts 3A on both sides and has a narrower width, that is, an elongated electrode width, compared to the first region.

[0025] The vias 5 formed for each connection part 3A have a planar shape with a plurality, for example, seven rectangular small vias 5A. Each small via 5A electrically connects between the connection part 3A of the heater electrode 3 and the electrode 4. The seven small vias 5A have a small via 5A1 closest to the main body 3B of the heater electrode 3 and six small vias 5A2 other than the small via 5A1. The long side of the small via 5A1 closest to the main body 3B faces the main body 3B side. The planar shape of the small via 5A1 is rectangular. The long side of the small via 5A1 is longer compared to the electrode width of the main body 3B of the heater electrode 3. The approximate center line X of the heater electrode 3 corresponds to the position of the optical waveguide 2, but the small via 5A1 shown in FIG. 2 is located directly above the optical waveguide 2. And the small via 5A1 is located on the approximate center line X of the heater electrode 3. The planar shape of the small via 5A2 is square. Note that the planar shape of the small via 5A2 is not limited to a square shape and may be circular and can be changed as appropriate.

[0026] It is assumed that current flows from the left electrode 4 in the figure, through the heater electrode 3, to the right electrode 4 in the figure. Since the conductivity of the heater electrode 3 is smaller than that of the via 5, the voltage of the heater electrode 3 in contact with the left via 5 and the right via 5 is stable. Although the voltage drop starts from the connection part 3A of the heater electrode 3 located at the left via 5, the change in the voltage drop becomes gentle. Then, the voltage gradually decreases from the main body 3B of the heater electrode 3 to the connection part 3A located at the right via 5. Further, the change in the voltage drop becomes gentle from the connection part 3A of the heater electrode 3 located at the right via 5, and the voltage drop stops.

[0027] At the connection part 3A of the heater electrode 3 located at the left via 5 (right via 5), since the change in the voltage drop becomes gentle, a situation where the current concentrates at the boundary between the via 5 and the heater electrode 3 can be avoided.

[0028] Among the plurality of small vias 5A in the phase shifter 1 of the first embodiment, the long side of the small via 5A1 closest to the main body 3B is arranged so as to face the main body 3B side. As a result, since the boundary between the heater electrode 3 and the small via 5A1 extends over the long side, current concentration in the heater electrode 3 can be suppressed. Moreover, since the via 5 has a plurality of small vias 5A, even if one small via 5A is disconnected, the other small vias 5A can be energized, so that energization to the heater electrode 3 is guaranteed and the reliability of energization can be ensured.

[0029] For the sake of convenience of explanation, the connection part 3A of the heater electrode 3 is connected to a plurality of small vias 5A, a part of the plurality of small vias 5A is located on the approximate center line X of the heater electrode 3, the upper surface of each small via 5A is rectangular, and the long side of the small via 5A1 faces the thinner main body 3B side of the heater electrode 3. Although the case where the small via 5A1 is located on the approximate center line X of the heater electrode 3 is illustrated, it may not be located on the approximate center line X and can be changed as appropriate.

[0030] For convenience of explanation, although the via 5 is exemplified as being formed of tungsten and the electrodes 4 are formed of Al, Cu, etc., the via 5 may be formed of the same material as the electrodes 4. In this case, since the manufacturing processes for forming the via 5 and the electrodes 4 can be made the same by forming the via 5 and the electrodes 4 of the same material, the manufacturability is improved.

[0031] Incidentally, for convenience of explanation, the phase shifter 1 is exemplified as the optical device of this embodiment, but the present invention is not limited to the phase shifter 1, and for example, it is also applicable to a DC modulator or a variable optical attenuator (VOA).

[0032] Also, although the case where the approximate center line X of the heater electrode 3 corresponds to the position of the optical waveguide 2 is exemplified, it is not particularly limited, and for example, an offset may be provided between the approximate center line X of the heater electrode 3 and the position of the optical waveguide 2.

Embodiment

[0033] FIG. 3 is a schematic plan view showing an example of the phase shifter 1A of Embodiment 2, and FIG. 4 is a schematic cross-sectional view taken along line A-A shown in FIG. 3. Incidentally, the same components as those of the phase shifter 1 of Embodiment 1 are denoted by the same reference numerals, and the description of the overlapping components and operations is omitted. The difference between the phase shifter 1 of Embodiment 1 and the phase shifter 1A of Embodiment 2 is that instead of the seven rectangular small vias 5A, three rectangular small vias 5B are arranged.

[0034] The three small vias 5B include one small via 5B1 closest to the main body 3B of the heater electrode 3 and two small vias 5B2 other than the small via 5B1. The long side of the small via 5B1 closest to the main body 3B faces the main body 3B. The long sides of the small vias 5B1 and 5B2 are made longer than the electrode width of the main body 3B of the heater electrode 3.

[0035] Among the plurality of small vias 5B in the phase shifter 1A of Example 2, the long side of the small via 5B1 closest to the main body 3B is arranged so as to face the main body 3B side. As a result, since the boundary between the heater electrode 3 and the small via 5B1 extends over the long side, current concentration in the heater electrode 3 can be suppressed. Moreover, since the via 5 has a plurality of small vias 5B, even if one small via 5B is disconnected, the other small vias 5B can be energized, so that energization to the heater electrode 3 is guaranteed and the reliability of energization can be ensured.

Example

[0036] FIG. 5 is a schematic plan view showing an example of the phase shifter 1B of Example 3, and FIG. 6 is a schematic cross-sectional view taken along line A-A shown in FIG. 5. For convenience of explanation, the same components as those of the phase shifter 1 of Example 1 are denoted by the same reference numerals, and the description of the overlapping components and operations is omitted. The difference between the phase shifter 1 of Example 1 and the phase shifter 1B of Example 3 is that instead of the seven rectangular small vias 5A, three rectangular small vias 5C are arranged.

[0037] The three small vias 5C include a small via 5C1 closest to the main body 3B of the heater electrode 3, a small via 5C3 farthest from the main body 3B, and a small via 5C2 arranged between the small via 5C1 and the small via 5C3. The long side of the small via 5C gradually becomes longer as it moves away from the main body 3B. The long side of each small via 5C is made longer than the electrode width of the main body 3B of the heater electrode 3. That is, the long side of the small via 5C3 is longer than the long side of the small via 5C2, and the long side of the small via 5C2 is longer than the long side of the small via 5C1. The long side of the small via 5C1 closest to the main body 3B faces the main body 3B.

[0038] In addition, the planar shape of the connection portion 3A1 of the heater electrode 3 is trapezoidal because the long sides of the respective small vias 5C gradually become longer as they move away from the main body 3B.

[0039] Among the plurality of small vias 5C in the phase shifter 1B of Example 3, the long side of the small via 5C1 closest to the main body 3B is arranged so as to face the main body 3B side. As a result, since the boundary between the heater electrode 3 and the small via 5C1 extends over the long side, current concentration in the heater electrode 3 can be suppressed. Moreover, since the via 5 has a plurality of small vias 5C, even if one small via 5C is disconnected, the other small vias 5C can be energized, so that energization to the heater electrode 3 is guaranteed and the reliability of energization can be ensured.

[0040] Furthermore, since the via 5 lengthens the long side of each small via 5C as it moves away from the main body 3B, the current spreads as it moves away from the main body 3B. As a result, current concentration can be suppressed by the spreading of the current.

[0041] Also, when the connection part 3A of the heater electrode 3 in Example 1 has a square or rectangular planar shape, the area of the heater electrode 3 increases, and thus the influence on other parts with respect to heater heating can be considered. However, since the planar shape of the connection part 3A1 in Example 3 is trapezoidal, the influence on other parts with respect to heater heating can be minimized.

[0042] In addition, although the case where the via 5 of the phase shifter 1A of Example 3 arranges three small vias 5C1, 5C2, and 5C3 having different long side lengths and a rectangular planar shape has been exemplified, it is not limited thereto and can be appropriately changed. Therefore, the embodiment will be described below as Example 4.

Example

[0043] FIG. 7 is a schematic plan view showing an example of the phase shifter 1D of Example 4, and FIG. 8 is a schematic cross-sectional view taken along line A-A shown in FIG. 7. The difference between the phase shifter 1C of Example 3 and the phase shifter 1D of Example 4 is that instead of three small vias 5C having a rectangular planar shape, three small vias 5D having an arc shape that is recessed away from the main body 3B are arranged.

[0044] The three small vias 5D include a small via 5D1 closest to the main body 3B of the heater electrode 3, a small via 5D3 farthest from the main body 3B, and a small via 5D2 disposed between the small via 5D1 and the small via 5D3. Each small via 5D has an arc length of the long side gradually increasing as it moves away from the main body 3B. The arc length of each small via 5D is longer compared to the electrode width of the main body 3B of the heater electrode 3. That is, the arc length of the small via 5D3 is longer compared to the arc length of the small via 5D2, and the arc length of the small via 5D2 is longer compared to the arc length of the small via 5D1. The long side of the small via 5D1 closest to the main body 3B faces the main body 3B.

[0045] Among the plurality of small vias 5D in the phase shifter 1C of Example 4, the arc of the small via 5D1 closest to the main body 3B is arranged to face the main body 3B side. As a result, since the boundary between the heater electrode 3 and the small via 5D1 extends over an arc, current concentration in the heater electrode 3 can be suppressed. Moreover, since the via 5 has a plurality of small vias 5D, even if one small via 5D is disconnected, the other small vias 5D can be energized, thus ensuring power supply to the heater electrode 3 and ensuring the reliability of power supply.

[0046] Furthermore, since the via 5 lengthens the arc of each small via 5D as it moves away from the main body 3B, the current spreads as it moves away from the main body 3B. As a result, current concentration can be suppressed by the spreading of the current. Moreover, since the small via 5D has an arc-shaped planar shape, the current density at the boundary with the heater electrode 3 can be made uniform, suppressing current concentration.

[0047] In addition, although the phase shifter 1C of Example 4 is exemplified by connecting the electrode 4 and the connection portion 3A1 of the heater electrode 3 with an arc-shaped small via 5D, it is not limited to an arc shape and can be appropriately changed.

[0048] For convenience of explanation, the optical waveguide 2 is exemplified by a channel-type waveguide, but it is not limited to a channel-type waveguide. For example, a rib-type waveguide or the like may be used and can be appropriately changed.

[0049] FIG. 9 is an explanatory diagram showing an example of the optical transceiver 60 of this embodiment. The optical transceiver 60 shown in FIG. 9 is connected to the output-side optical fiber 61A (61) and the input-side optical fiber 61B (61). The optical transceiver 60 includes a DSP (Digital Signal Processor) 62, a light source 63, and an optical transceiver 64. The DSP 62 is an electrical component that executes digital signal processing. The optical transceiver 64 includes an optical transmitter 64A and an optical receiver 64B. The DSP 62 executes processes such as encoding of transmission data, for example, generates an electrical signal including the transmission data, and outputs the generated electrical signal to the optical transmitter 64A. Also, the DSP 62 acquires an electrical signal including the received data from the optical receiver 64B, and executes processes such as decoding of the acquired electrical signal to obtain the received data.

[0050] The light source 63 includes, for example, a laser diode or the like, generates light of a predetermined wavelength, and supplies it to the optical transmitter 64A and the optical receiver 64B. The optical transmitter 64A has an optical modulator element 64A1 that outputs signal light obtained by modulating the light supplied from the light source 63 by the electrical signal output from the DSP 62 to the optical fiber 61A. The optical modulator element 64A1 includes a phase shifter or the like. The optical modulator element 64A1 generates signal light by modulating the light that propagates through the waveguide in accordance with the electrical signal when the light supplied from the light source 63 propagates through the waveguide.

[0051] The optical receiver 64B has an optical receiver element 64B1 that receives the received light from the optical fiber 61B and demodulates the received light using the light supplied from the light source 63. Then, the optical receiver element 64B1 converts the demodulated received light into an electrical signal, and outputs the converted electrical signal to the DSP 62. Note that the optical receiver element 64B1 also includes a photodetector or the like.

[0052] Since the optical transmitter 64A and the optical receiver 64B are integrated on one chip in the optical transceiver 60, it can greatly contribute to the miniaturization of the entire optical transceiver 60.

[0053] The optical transceiver 60 has been illustrated by way of example as incorporating both the optical transmitter 64A and the optical receiver 64B. However, the optical transceiver 60 may incorporate only one of the optical transmitter 64A and the optical receiver 64B, and can be changed as appropriate.

[0054] In addition, although a phase shifter used in the optical modulator element 64A1 of the optical transmitter 64A has been illustrated as the optical device, it may also be applied to the photodetector in the optical receiver element 64B1 of the optical receiver 64B, and can be changed as appropriate.

[0055] The photodetector includes a core layer including a silicon region formed on a clad layer formed on a silicon substrate, a GePD formed of a germanium layer including a germanium region formed on the core layer, and a resistor surrounding the silicon region. The resistor has a heater electrode, an electrode electrically connected to the heater electrode, and a via connecting between the heater electrode and the electrode. By applying a voltage from the electrode to the heater electrode via the via, the germanium layer of the GePD is heated.

[0056] As shown in FIG. 1, the heater electrode has two wide connection portions and a main body connecting the connection portions on both sides. And, by arranging the via structures of Examples 1 to 5 between the connection portion of the heater electrode and the electrode, current concentration can be suppressed. That is, also in the photodetector, since the boundary between the heater electrode and the small via extends over the long side, current concentration in the heater electrode can be suppressed. Moreover, since the via has a plurality of small vias, even if one small via is disconnected, the other small vias can be energized, so that energization to the heater electrode is guaranteed and the reliability of energization can be ensured.

Explanation of Symbols

[0057] 1 Phase shifter 2 Optical waveguide 3 Heater electrode 3A Connection portion 3B Main body 4 Electrode 5 Via 5A, 5B, 5C, 5D Small via 5A1, 5B1, 5C1, 5D1 Small via

Claims

1. An optical device having a heater electrode formed on a substrate, an electrode for energizing the heater electrode, and a plurality of through electrodes connecting between the heater electrode and the electrode, wherein the heater electrode has a first region, and a second region connected to the first region and having a narrower width compared to the first region, and the through electrodes are formed between the first region and the electrode, and among the plurality of through electrodes, the long side of the through electrode closest to the second region is arranged to face the second region side. The optical device is characterized by this.

2. The planar shape of the through electrode closest to the second region is rectangular. The optical device according to claim 1 is characterized by this.

3. The optical device according to claim 1, wherein the long side of the through electrode is arranged to face the second region side.

4. The planar shape of the through electrode is rectangular. The optical device according to claim 1 is characterized by this.

5. The planar shape of the through electrode closest to the second region is an arc shape recessed so as to be away from the second region. The optical device according to claim 1 is characterized by this.

6. The planar shape of the through electrode is an arc shape recessed so as to be away from the second region. The optical device according to claim 1 is characterized by this.

7. Each through electrode formed in the first region is characterized in that the long side becomes longer as it is away from the second region. The optical device according to any one of claims 1 to 6 is characterized by this.

8. The planar shape of the first region is characterized in that the width of the long side expands as it is away from the second region. The optical device according to claim 7 is characterized by this.

9. The through electrode closest to the second region is arranged on the approximate center line of the heater electrode. The optical device according to claim 1 is characterized by this.

10. An optical transmitter having an optical modulator element that modulates light generated from a light source using an electrical signal, wherein the phase shifter in the optical modulator element has a heater electrode formed on a substrate, an electrode for energizing the heater electrode, and a plurality of through electrodes connecting between the heater electrode and the electrode, and the heater electrode has a first region, and a second region connected to the first region and having a narrower width compared to the first region, and the through electrodes are An optical transmitter, characterized in that it is formed between the first region and the electrode, and the long side of the through electrode closest to the second region among the plurality of through electrodes is arranged to face the second region side. **Claim 11** An optical receiver having an optical receiver element that obtains an electrical signal from received light using light from a light source, wherein the photodetector in the optical receiver element has a heater electrode formed on a substrate, an electrode for energizing the heater electrode, and a plurality of through electrodes connecting between the heater electrode and the electrode, wherein the heater electrode has a first region, and a second region that is connected to the first region and has a narrower width than the first region, wherein the through electrodes are formed between the first region and the electrode, and the long side of the through electrode closest to the second region among the plurality of through electrodes is arranged to face the second region side. An optical receiver characterized by this.

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