Optical device, optical transmitter, and optical transceiver

Abstract

The invention relates to an optical device, an optical transmitter and an optical transceiver. An optical device includes a first chip and a second chip having a material with a high electro-optical effect. The first chip includes: a first waveguide that propagates a light beam from the first port; a first branch waveguide that propagates the light beam from the first waveguide; the folded parallel waveguide is connected with the first branch waveguide; and a first parallel waveguide that propagates the light beam from the turn-back parallel waveguide. The first chip includes: a second waveguide that propagates the light beam from the second port; a second branch waveguide that propagates the light beam from the second waveguide; and a phase regulator that regulates the phase of the light beam propagating through the first branch waveguide. The second chip includes a second parallel waveguide coupling the first parallel waveguide and the second branch waveguide, and a phase modulator that adjusts the phase of the light beam propagating in the second parallel waveguide.

Description

Technical Field

[0001] The embodiments discussed herein relate to optical devices, optical transmitters, and optical transceivers. Background Art

[0002] A conventional optical modulator includes, for example, a waveguide disposed on a substrate and a signal electrode and a ground electrode disposed near the waveguide, and when a voltage is applied to the signal electrode, an electric field is generated in the waveguide, the electric field in the waveguide changes the refractive index of the waveguide, and the phase of the light changes. The waveguide constitutes a Mach-Zehnder interferometer, and the difference between the phases of the light of the waveguide changes the light output.

[0003] The light modulator is, for example, a Mach-Zehnder modulator. Figure 6 2 is a schematic plan view of an example of a conventional optical modulator 200. The optical modulator 200 includes, for example, a thin-film lithium niobate (LN: LiNbO3) chip 201, a microlens array (MLA) 202, and a polarization rotator (PR) 203. In addition, the optical modulator 200 includes a polarization beam combiner (PBC) 204 and an optical fiber array 205.

[0004] The thin film LN chip 201 includes a first port 201A, a first waveguide 211, a turned-back waveguide 212, a first branch portion 213, and two first branch waveguides 214. The thin film LN chip 201 includes two second branch portions 215, four second branch waveguides 216, and four third branch portions 217. The thin film LN chip 201 includes eight third branch waveguides 218, four radio frequency (RF) modulation units 230, four first direct current (DC) modulation units 240, and four first multiplexing units 219. The thin film LN chip 201 includes four fourth branch waveguides 220, two second DC modulation units 250, a second multiplexing unit 221, two output waveguides 222, and a second port 201B.

[0005] The first port 201A is a port provided at one end of the thin film LN chip 201, connected to the MLA 202, and connected to the first waveguide 211. The first waveguide 211 is, for example, an LN waveguide that propagates a signal light beam from the first port 201A. An input end of the first waveguide 211 is exposed to one end surface of the thin film LN chip 201. The first waveguide 211 outputs the signal light beam from the input end to the return waveguide 212. The return waveguide 212 is, for example, an LN waveguide that propagates a signal light beam from the first waveguide 211.

[0006] The first branch portion 213 branches the signal beam from the return waveguide 212 into two first branch waveguides 214. The first branch waveguide 214 is, for example, an LN waveguide that propagates the signal beam from the first branch portion 213. The second branch portion 215 branches the signal beam from the first branch waveguide 214 into two second branch waveguides 216. The second branch waveguide 216 is, for example, an LN waveguide that propagates the signal beam from the second branch portion 215. The third branch portion 217 branches the signal beam from the second branch waveguide 216 into two third branch waveguides 218 in the RF modulation unit 230.

[0007] The RF modulation unit 230 is a phase modulation unit that modulates the signal light beam propagating through the two third branch waveguides 218 at high speed. The RF modulation unit 230 includes two third branch waveguides 218 arranged in parallel, a plurality of RF electrodes 231 arranged in parallel to the two third branch waveguides 218, and an RF driver 232 that inputs a high-frequency signal to the RF electrodes 231. In addition, the RF modulation unit 230 includes: an RF termination 233 that terminates the high-frequency signal of the RF electrode 231; and an electrode line 234 that electrically connects the RF electrode 231 and the RF driver 232. The two third branch waveguides 218 are LN waveguides. For example, when a high-frequency signal having a frequency band of tens of GHz is input from the RF driver 232 to the RF electrode 231, the RF modulation unit 230 can modulate the signal light beam propagating through the third branch waveguide 218 at high speed according to the high-frequency signal.

[0008] The first DC modulation unit 240 includes two third branch waveguides 218 arranged in parallel, and a plurality of first DC electrodes 241 arranged in parallel on the two third branch waveguides 218. The two third branch waveguides 218 are, for example, LN waveguides. The first DC modulation unit 240 is a phase adjustment unit that connects the two third branch waveguides 218 in the RF modulation unit 230 and the two third branch waveguides 218 in the first DC modulation unit 240 and modulates the signal light beam propagating through the two third branch waveguides 218 in the first DC modulation unit 240. When a bias voltage is applied to the first DC electrode 241, the first DC modulation unit 240 adjusts the bias for turning on / off the signal light beam propagating through the third branch waveguide 218 according to the on / off of the bias voltage. As a result, the bias for turning on / off the signal light beam propagating through the third branch waveguide 218 is adjusted, so that the phase of the signal light beam propagating through the third branch waveguide 218 can be adjusted. The first multiplexing unit 219 multiplexes the signal beams from the two third branch waveguides 218 in the first DC modulation unit 240 and outputs the multiplexed signal beam to the fourth branch waveguide 220 .

[0009] The second DC modulation unit 250 includes two fourth branch waveguides 220 arranged in parallel, and a second DC electrode 251 arranged on the two fourth branch waveguides 220. The two fourth branch waveguides 220 are, for example, LN waveguides. The second DC modulation unit 250 is a phase adjustment unit that connects the two first multiplexing units 219 with the two fourth branch waveguides 220 in the second DC modulation unit 250, and modulates the signal light beams propagating through the two fourth branch waveguides 220 in the second DC modulation unit 250. When a bias voltage is applied to the second DC electrode 251, the second DC modulation unit 250 adjusts the bias for turning on / off the signal light beam propagating through the fourth branch waveguide 220 according to the on / off of the bias voltage. As a result, the bias for turning on / off the signal light beam propagating through the fourth branch waveguide 220 is adjusted, so that the phase of the signal light beam propagating through the fourth branch waveguide 220 can be adjusted. The second DC modulation unit 250 modulates the signal light beam propagating through the fourth branch waveguide 220, and outputs the modulated signal light beam to the second multiplexing unit 221. The second multiplexing unit 221 multiplexes the modulated signal light beams from the two fourth branch waveguides 220 in the second DC modulation unit 250, and outputs the multiplexed signal light beam to the output waveguide 222.

[0010] One second multiplexing unit 221 multiplexes the signal beams from the two fourth branch waveguides 220 in one second DC modulation unit 250, and outputs the multiplexed signal beam to one output waveguide 222. Another second multiplexing unit 221 multiplexes the signal beams from the two fourth branch waveguides 220 in another second DC modulation unit 250, and outputs the multiplexed signal beam to another output waveguide 222. The second port 201B is provided at one end of the thin film LN chip 201, and includes a port connected to the one output waveguide 222 and a port connected to the another output waveguide 222.

[0011] The output waveguide 222 is, for example, an LN waveguide that propagates a signal light beam from the second multiplexing unit 221. The second port 201B connected to the output end of the output waveguide 222 is exposed to one end surface of the thin film LN chip 201. The MLA 202 is an optical component that optically connects one output waveguide 222 and the PR 203 and optically connects the other output waveguide 222 and the PBC 204. The MLA 202 optically connects the first waveguide 211 and the optical fiber 205A on the input side in the optical fiber array 205. The MLA 202 converges the signal light beam from the optical fiber 205A on the input side in the optical fiber array 205 in the first waveguide 211. The MLA 202 converges the signal light beam from the one output waveguide 222 in the PR 203, and converges the signal light beam from the other output waveguide 222 in the PBC 204.

[0012] The PR 203 performs polarization rotation on the signal beam from one output waveguide 222 via the MLA 202, and outputs the polarization-rotated signal beam to the PBC 204. The PBC 204 polarization-multiplexes the polarization-rotated signal beam from the PR 203 and the signal beam from the other output waveguide 222 via the MLA 202, and outputs the polarization-multiplexed signal beam to the optical fiber 205B on the output side of the optical fiber array 205.

[0013] The optical modulator 200 can modulate the signal beam by inputting a high-frequency signal output from the RF driver 232 to the RF electrode 231 via the electrode line 234 and causing the high-frequency signal to propagate in the same direction as the signal beam propagating through the third branch waveguide 218 .

[0014] Patent Document 1: U.S. Patent Application Publication No. 2023 / 0152660

[0015] Patent Document 2: U.S. Patent Application Publication No. 2021 / 0373412

[0016] Patent Document 3: International Publication Pamphlet No. WO 2015 / 012213

[0017] Patent Document 4: Japanese Laid-Open Patent Publication No. 2012-163876

[0018] In the optical modulator 200, the first DC modulation unit 240 and the second DC modulation unit 250 become larger in size, so the thin film LN chip 201 becomes larger in size. In addition, the MLA 202, the PR 203, and the PBC 204 are separate components, so the package size of the thin film LN chip 201 becomes larger.

[0019] Therefore, it is necessary to miniaturize the chip size of the optical modulator by integrating the first DC modulation unit 240, the second DC modulation unit 250, the PR 203, and the PBC 204 on a silicon photonics (SiPh) chip and mounting a thin film LN chip on the SiPh chip.

[0020] Therefore, an object of one aspect of an embodiment of the present invention is to provide a small optical device or the like. Summary of the invention

[0021] According to aspects of the embodiments, an optical device includes a first chip and a second chip. The first chip includes a first port and a second port. The second chip is arranged on the first chip and has a material having an electro-optical effect higher than that of the first chip. The first chip includes a first waveguide, a first branch waveguide, a folded parallel waveguide, a first parallel waveguide, a second waveguide, a second branch waveguide and a phase adjuster. The first waveguide is connected to the first port and propagates a signal beam from the first port. The first branch waveguide is connected to the first waveguide and has a branch structure for propagating a signal beam from the first waveguide. The folded parallel waveguide is connected to the first branch waveguide and has a folded structure. The first parallel waveguide is connected to the folded parallel waveguide and propagates a signal beam from the folded parallel waveguide. The second waveguide is connected to the second port and propagates a signal beam to the second port. The second branch waveguide is connected to the second waveguide and has a branch structure for propagating a signal beam to the second waveguide. The phase adjuster is arranged on the first branch waveguide and adjusts the phase of the signal beam propagating through the first branch waveguide according to a direct current signal. The second chip includes a second parallel waveguide and a phase modulator. The second parallel waveguide is connected to the first parallel waveguide on a first end face, is connected to the second branch waveguide on a second end face different from the first end face, and propagates the signal light beam from the first parallel waveguide to the second branch waveguide. The phase modulator is arranged on the second parallel waveguide, and modulates the phase of the signal light beam propagating through the second parallel waveguide according to the high-frequency signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic plan view illustrating an example of an optical modulator according to Embodiment 1;

[0023] Figure 2 is a schematic plan view illustrating an example of an optical modulator according to Embodiment 2;

[0024] Figure 3 is a schematic plan view illustrating an example of an optical modulator according to Embodiment 3;

[0025] Figure 4 is an explanatory diagram illustrating an example of an optical transceiver according to the present embodiment;

[0026] Figure 5 is a schematic plan view of an example of an optical modulator according to a comparative example; and

[0027] Figure 6 is a schematic plan view of an example of a conventional light modulator. DETAILED DESCRIPTION

[0028] Comparative Example 1

[0029] Figure 5 is a schematic plan view of an example of an optical modulator 100 according to a comparative example. Figure 5 The illustrated optical modulator 100 includes a SiPh chip 101 on which are mounted first DC modulation units 140 each including a first heater electrode 141 and second DC modulation units 150 each including a second heater electrode 151. The optical modulator 100 includes: a thin-film lithium niobate (LN: LiNbO3) chip 102 on which are mounted RF modulation units 130 each including an RF electrode 132; and an optical fiber array 103 including an optical fiber 103A on the input side and an optical fiber 103B on the output side.

[0030] The SiPh chip 101 includes a Si substrate, an opening portion 101A opened at a portion of the Si substrate, a first port 101B provided on one end surface, and a second port 101C provided on one end surface. The opening portion 101A has a structure formed by etching out a portion of the Si substrate. The opening portion 101A is a portion where the thin film LN chip 102 is mounted.

[0031] The SiPh chip 101 includes one first waveguide 111, a return waveguide 112, one first branch portion 113, two first branch waveguides 114, two second branch portions 115, and four second branch waveguides 116. The SiPh chip 101 includes four third branch portions 117 and four third branch waveguides 118A.

[0032] The SiPh chip 101 includes eight fourth branch waveguides 118B, four first direct current (DC) modulation units 140, and four first multiplexing units 119. The SiPh chip 101 includes four fifth branch waveguides 120, two second DC modulation units 150, a second multiplexing unit 121, and two first output waveguides 122. The SiPh chip 101 includes a polarization rotator (PR) 124, a polarization beam combiner (PBC) 125, and a second output waveguide 123.

[0033] The thin film LN chip 102 includes eight parallel waveguides 131 and four radio frequency (RF) modulation units 130. The first waveguide 111 in the SiPh chip 101 is, for example, a Si waveguide that propagates a signal beam from the first port 101B. The input end of the first waveguide 111 is connected to the optical fiber 103A on the input side of the optical fiber array 103. The first waveguide 111 outputs the signal beam from the first port 101B to the return waveguide 112. The return waveguide 112 is, for example, a Si waveguide that propagates a signal beam from the first waveguide 111.

[0034] The first branch portion 113 branches the signal light beam from the return waveguide 112 into two first branch waveguides 114. The first branch waveguide 114 is, for example, a Si waveguide that propagates the signal light beam from the first branch portion 113. The second branch portion 115 branches the signal light beam from the first branch waveguide 114 into two second branch waveguides 116. The second branch waveguide 116 is, for example, a Si waveguide that propagates the signal light beam from the second branch portion 115. The third branch portion 117 branches the signal light beam from the second branch waveguide 116 into two third branch waveguides 118A.

[0035] The RF modulation unit 130 is a phase modulation unit that modulates a signal light beam propagating through a parallel waveguide 131 connected to the third branch waveguide 118A at high speed. The RF modulation unit 130 includes two parallel waveguides 131 arranged in parallel, a plurality of RF electrodes 132 arranged in parallel to the two parallel waveguides 131, and an RF driver 133 that inputs a high-frequency signal to the RF electrode 132. In addition, the RF modulation unit 130 includes an RF terminal 134 that terminates the high-frequency signal of the RF electrode 132. The two parallel waveguides 131 are LN waveguides. For example, when a high-frequency signal having a frequency band of several tens of GHz is input from the RF driver 133 to the RF electrode 132, the RF modulation unit 130 can modulate the signal light beam propagating through the parallel waveguide 131 at high speed according to the high-frequency signal. The SiPh chip 101 includes an electrode line 126 that electrically connects the RF electrode 132 and the RF driver 133 in the thin film LN chip 102. Note that, for example, Al is used for the electrode line 126.

[0036] The first DC modulation unit 140 includes two fourth branch waveguides 118B arranged in parallel, a plurality of first heater electrodes 141 arranged in parallel on the two fourth branch waveguides 118B, and an electrode line 142 electrically connected to the first heater electrode 141. The two fourth branch waveguides 118B are, for example, Si waveguides. The first DC modulation unit 140 is a phase adjustment unit that connects the two parallel waveguides 131 in the RF modulation unit 130 and the two fourth branch waveguides 118B in the first DC modulation unit 140, and modulates the signal light beam propagating through the two fourth branch waveguides 118B. When current flows through the first heater electrode 141, the first DC modulation unit 140 heats the fourth branch waveguide 118B by the heat generated by the first heater electrode 141. As a result, the thermo-optical effect changes the refractive index of the fourth branch waveguide 118B, so that the phase of the signal light beam propagating through the fourth branch waveguide 118B can be adjusted. The first multiplexing unit 119 multiplexes the signal beams from the two fourth branch waveguides 118B in the first DC modulation unit 140 , and outputs the multiplexed signal beam to the fifth branch waveguide 120 .

[0037] The second DC modulation unit 150 includes two fifth branch waveguides 120 arranged in parallel, a second heater electrode 151 arranged on the two fifth branch waveguides 120, and an electrode line 152 electrically connected to the second heater electrode 151. The two fifth branch waveguides 120 are, for example, Si waveguides. The second DC modulation unit 150 is a phase adjustment unit that connects the two fifth branch waveguides 120 in the two first multiplexing units 119 and the second DC modulation unit 150, and modulates the signal light beams propagating through the two fifth branch waveguides 120 in the second DC modulation unit 150. When current flows through the second heater electrode 151, the second DC modulation unit 150 heats the fifth branch waveguide 120 by the heat generated by the second heater electrode 151. As a result, the thermo-optical effect changes the refractive index of the fifth branch waveguide 120, so that the phase of the signal light beam propagating through the fifth branch waveguide 120 can be adjusted. The second DC modulation unit 150 modulates the signal beam propagating through the fifth branch waveguide 120, and outputs the modulated signal beam to the second multiplexing unit 121. The second multiplexing unit 121 multiplexes the modulated signal beams from the two fifth branch waveguides 120 in the second DC modulation unit 150, and outputs the multiplexed signal beam to the first output waveguide 122.

[0038] One second multiplexing unit 121 multiplexes the signal beams from the two fifth branch waveguides 120 in one second DC modulation unit 150, and outputs the multiplexed signal beam to one first output waveguide 122. Another second multiplexing unit 121 multiplexes the signal beams from the two fifth branch waveguides 120 in another second DC modulation unit 150, and outputs the multiplexed signal beam to another first output waveguide 122. The first output waveguide 122 is, for example, a Si waveguide that propagates the signal beam from the second multiplexing unit 121.

[0039] The PR 124 polarization-rotates a signal beam from one second multiplexing unit 121 via one first output waveguide 122, and outputs the polarization-rotated signal beam to the PBC 125. The PBC 125 polarization-multiplexes the polarization-rotated signal beam from the PR 124 and a signal beam from another second multiplexing unit 121 via another first output waveguide 122, and outputs the polarization-multiplexed signal beam to the optical fiber 103B on the output side of the optical fiber array 103.

[0040] The chip size of the optical modulator 100 can be miniaturized by integrating the first DC modulation unit 140, the second DC modulation unit 150, the PR 124, and the PBC 125 on the SiPh chip 101 and mounting the thin film LN chip 102 on the SiPh chip 101 in the optical modulator 100. In addition, there is no need to adjust the optical axis of each of the optical fiber 103A on the input side and the optical fiber 103B on the output side, the PR 124, and the PBC 125 in the optical fiber array 103, so that the installation cost can be reduced.

[0041] However, in the optical modulator 100, the RF electrode 132 of the thin film LN chip 102 is connected to the RF driver 133 via the electrode line 126 on the SiPh chip 101. As a result, the propagation loss of the high-frequency signal becomes significant due to the use of Al for the electrode line 126, and thus the modulation band deteriorates. Moreover, the loss per unit length of the waveguide of the SiPh chip 101 is significant, and thus the loss of light becomes significant.

[0042] Therefore, an embodiment for dealing with this situation will be described below as Embodiment 1.

[0043] Implementation Method 1

[0044] Figure 1 is a schematic plan view illustrating an example of the light modulator 1 according to Embodiment 1. Figure 1The illustrated optical modulator 1 includes a SiPh chip 2 as a first chip on which are mounted first DC modulation units 40 each including a first heater electrode 41 and second DC modulation units 50 each including a second heater electrode 51. The optical modulator 1 includes: a thin-film lithium niobate (LN: LiNbO3) chip 3 as a second chip on which are mounted RF modulation units 30 each including an RF electrode 32; and an optical fiber array 4 including an optical fiber 4A on the input side and an optical fiber 4B on the output side. The electro-optical effect of the material of the thin-film LN chip 3 is higher than that of the material of the SiPh chip 2.

[0045] The SiPh chip 2 includes a Si substrate, an opening portion 2A opened at a portion of the Si substrate, a first port 2B provided on one end surface, and a second port 2C provided on one end surface. The opening portion 2A has a structure formed by etching out a portion of the Si substrate. The opening portion 2A is a portion where the thin film LN chip 3 is mounted.

[0046] The SiPh chip 2 includes one first waveguide 11, one first branch portion 12, two first front-stage branch waveguides 13, two second branch portions 14, and four second front-stage branch waveguides 15. Note that the first front-stage branch waveguide 13 and the second front-stage branch waveguide 15 constitute the front-stage branch waveguide 60. The SiPh chip 101 includes four third branch portions 16, eight first branch waveguides 17A, a folded parallel waveguide 18, and eight first parallel waveguides 17B. The first branch waveguide 17A constitutes a rear-stage branch waveguide.

[0047] The SiPh chip 2 includes eight second branch waveguides 17C, four first multiplexing units 19, four third branch waveguides 20, two second multiplexing units 21, and two first output waveguides 22. The SiPh chip 2 includes a polarization rotator (PR) 24, a polarization beam combiner (PBC) 25, and a second output waveguide 23.

[0048] The SiPh chip 2 includes four first direct current (DC) modulation units 40 and two second DC modulation units 50. The thin film LN chip 3 includes eight second parallel waveguides 31 and four radio frequency (RF) modulation units 30.

[0049] The first waveguide 11 in the SiPh chip 2 is, for example, a Si waveguide that propagates the signal beam from the first port 2B. The input end of the first waveguide 11 is connected to the optical fiber 4A on the input side of the optical fiber array 4. The first waveguide 11 outputs the signal beam from the first port 2B to the first branch portion 12.

[0050] The first branch portion 12 branches the signal light beam from the first waveguide 11 into two first front-stage branch waveguides 13. The first front-stage branch waveguide 13 is, for example, a Si waveguide that propagates the signal light beam from the first branch portion 12. The first front-stage branch waveguide 13 outputs the signal light beam from the first branch portion 12 to the second branch portion 14. The second branch portion 14 branches the signal light beam from the first front-stage branch waveguide 13 into two second front-stage branch waveguides 15. The second front-stage branch waveguide 15 is, for example, a Si waveguide that propagates the signal light beam from the second branch portion 14. The second front-stage branch waveguide 15 outputs the signal light beam from the second branch portion 14 to the third branch portion 16. The third branch portion 16 branches the signal light beam from the second front-stage branch waveguide 15 into two first branch waveguides 17A.

[0051] The first branch waveguide 17A is, for example, a Si waveguide that propagates the signal light beam from the third branch portion 16. The first branch waveguide 17A outputs the signal light beam from the third branch portion 16 to the folded parallel waveguide 18. The folded parallel waveguide 18 is, for example, a Si waveguide that propagates the signal light beam from the first branch waveguide 17A. The folded parallel waveguide 18 outputs the signal light beam from the first branch waveguide 17A to the first parallel waveguide 17B. The first parallel waveguide 17B is, for example, a Si waveguide that propagates the signal light beam from the first branch waveguide 17A. The first parallel waveguide 17B is connected to the second parallel waveguide 31 in the thin film LN chip 3.

[0052] The second DC modulation unit 50 includes two second front-stage branch waveguides 15 arranged in parallel, a second heater electrode 51 arranged on the two second front-stage branch waveguides 15, and an electrode line 52 electrically connected to the second heater electrode 51. The two second front-stage branch waveguides 15 are, for example, Si waveguides. The second DC modulation unit 50 is a phase adjustment unit that modulates the signal light beam propagating through the two second front-stage branch waveguides 15. When current flows to the second heater electrode 51, the second DC modulation unit 50 heats the second front-stage branch waveguide 15 by the heat generated by the second heater electrode 51. As a result, the thermo-optical effect changes the refractive index of the second front-stage branch waveguide 15, so that the phase of the signal light beam propagating through the second front-stage branch waveguide 15 can be adjusted. The second DC modulation unit 50 modulates the signal light beam propagating through the second front-stage branch waveguide 15, and outputs the modulated signal light beam to the third branch portion 16.

[0053] The first DC modulation unit 40 includes two first branch waveguides 17A arranged in parallel, a plurality of first heater electrodes 41 arranged in parallel on the two first branch waveguides 17A, and an electrode line 42 electrically connected to the first heater electrodes 41. The first DC modulation unit 40 is a phase adjustment unit that modulates a signal light beam propagating through the two first branch waveguides 17A. When current flows through the first heater electrode 41, the first DC modulation unit 40 heats the first branch waveguide 17A by heat generated by the first heater electrode 41. As a result, the thermo-optical effect changes the refractive index of the first branch waveguide 17A, so that the phase of the signal light beam propagating through the first branch waveguide 17A can be adjusted. The first DC modulation unit 40 modulates the signal light beam propagating through the first branch waveguide 17A, and outputs the modulated signal light beam to the first parallel waveguide 17B.

[0054] The RF modulation unit 30 is a phase modulation unit that modulates the signal light beam propagating through the second parallel waveguide 31 connected to the first parallel waveguide 17B at high speed. The RF modulation unit 30 includes two second parallel waveguides 31 arranged in parallel, a plurality of RF electrodes 32 arranged in parallel to the two second parallel waveguides 31, and an RF driver 33 as a driver circuit that inputs a high-frequency signal to the RF electrode 32. In addition, the RF modulation unit 30 includes an RF terminal 34 that terminates the high-frequency signal of the RF electrode 32. For example, when a high-frequency signal having a frequency band of several tens of GHz is input from the RF driver 33 to the RF electrode 32, the RF modulation unit 30 can modulate the signal light beam propagating through the second parallel waveguide 31 at high speed according to the high-frequency signal. The SiPh chip 2 includes an electrode line 26 that electrically connects the RF electrode 32 in the thin film LN chip 3 and the RF driver 33. The RF modulation unit 30 modulates the signal light beam propagating through the second parallel waveguide 31 at high speed, and outputs the signal light beam modulated at high speed to the second branch waveguide 17C.

[0055] The optical modulator 1 includes eight branch waveguides Wg1 to Wg8 constituting a Mach-Zehnder interferometer. Each branch waveguide is formed by connecting the waveguide of the first branch waveguide 17A, the waveguide of the folded parallel waveguide 18, the waveguide of the first parallel waveguide 17B, the waveguide of the second parallel waveguide 31, and the waveguide of the second branch waveguide 17C. In the Mach-Zehnder interferometer, the six branch waveguides Wg2 to Wg7 are arranged in parallel between the branch waveguide Wg1 on the inner circumference side of the folded parallel waveguide 18 and the branch waveguide Wg8 on the outer circumference side of the folded parallel waveguide 18.

[0056] The second branch waveguide 17C is connected to the second parallel waveguide 31 in the RF modulation unit 30, and outputs the signal beam modulated by the RF modulation unit 30 to the first multiplexing unit 19. The first multiplexing unit 19 multiplexes the signal beams from the second branch waveguide 17C, and outputs the multiplexed signal beams to the third branch waveguide 20. The second multiplexing unit 21 multiplexes the signal beams from the corresponding third branch waveguides 20, and outputs the multiplexed signal beams to the first output waveguide 22.

[0057] One second multiplexing unit 21 multiplexes the signal beams from the two third branch waveguides 20, and outputs the multiplexed signal beam to one first output waveguide 22. Another second multiplexing unit 21 multiplexes the signal beams from the other two third branch waveguides 20, and outputs the multiplexed signal beam to another first output waveguide 22.

[0058] The PR 24 polarization-rotates a signal beam from one second multiplexing unit 21 via one first output waveguide 22, and outputs the polarization-rotated signal beam to the PBC 25. The PBC 25 polarization-multiplexes the polarization-rotated signal beam from the PR 24 and the signal beam from another second multiplexing unit 21 via another first output waveguide 22, and outputs the polarization-multiplexed signal beam to the optical fiber 4B on the output side of the optical fiber array 4.

[0059] In the optical modulator 1 according to embodiment 1, the first DC modulation unit 40 and the second DC modulation unit 50 are arranged before the input stage of the folded parallel waveguide 18, and the RF modulation unit 30 is arranged after the output stage of the folded parallel waveguide 18, so that the chip size of the entire optical modulator 1 can be miniaturized.

[0060] In the optical modulator 1, the RF electrode 32 of the thin film LN chip 3 is connected to the RF driver 33 via the electrode line 26 on the SiPh chip 2. Figure 5 The electrode lines in the SiPh chip 2 are short. As a result, the degradation of the modulation band can be suppressed by reducing the propagation loss of the high-frequency signal and achieving speed matching between the high-frequency signal and the signal light beam. In addition, although the loss per unit length of the waveguide of the SiPh chip 2 increases, the waveguide length of the SiPh chip 2 can be shortened in the length direction of the SiPh chip 2, so that the loss of light can be reduced.

[0061] The optical modulator 1 has eight branch waveguides Wg1 to Wg8 of different waveguide lengths constituting a Mach-Zehnder interferometer, and therefore assumes a situation where a phase difference of light is generated between the branch waveguides when the temperature changes and the output of the signal light beam becomes unstable. Therefore, an embodiment for dealing with such a situation will be described below as embodiment 2.

[0062] Implementation Method 2

[0063] Figure 2 1 is a schematic plan view illustrating an example of an optical modulator 1A according to Embodiment 2. Note that the same components as those of the optical modulator 1 according to Embodiment 1 are denoted by the same reference numerals, and descriptions of duplicate components and operations will be omitted. The difference between the optical modulator 1A according to Embodiment 2 and the optical modulator 1 according to Embodiment 1 is that the optical modulator 1A includes a front-stage branch waveguide 60A that is arranged in a direction substantially perpendicular to the first waveguide 11 and connects the first waveguide 11 and the first branch waveguide 17A1.

[0064] The first waveguide 11 and the first branch waveguide 17A1 are arranged in parallel with the second parallel waveguide 31. The front-stage branch waveguide 60A includes two first front-stage branch waveguides 13A connected to the first waveguide 11, and two second front-stage branch waveguides 15A connected to the first front-stage branch waveguide 13A. The front-stage branch waveguide 60A is a waveguide that is connected to the first waveguide 11 and changes the traveling direction of the first waveguide 11. The two first branch waveguides 17A1 connected to the second front-stage branch waveguide 15A are rear-stage branch waveguides that connect the front-stage branch waveguide 60A and the folded-back parallel waveguide 18 and return the traveling direction to the original traveling direction.

[0065] The first branch waveguide 17A1 includes a fourth branch waveguide 17A11 connected to the second preceding branch waveguide 15A and a curved parallel waveguide 17A12 having a curved structure connected to the fourth branch waveguide 17A11. The first branch waveguide 17A1 includes a parallel waveguide 17A13 connecting the curved parallel waveguide 17A12 and the return parallel waveguide 18.

[0066] The eight branch waveguides Wg1 to Wg8 constituting the Mach-Zehnder interferometer of the optical modulator 1A are waveguides between the second branch portion 14 and the first multiplexing unit 19. Each branch waveguide is formed by connecting the waveguide of the first branch waveguide 17A1, the waveguide of the folded parallel waveguide 18, the waveguide of the first parallel waveguide 17B, the waveguide of the second parallel waveguide 31, and the waveguide of the second branch waveguide 17C. In the Mach-Zehnder interferometer, the six branch waveguides Wg2 to Wg7 are arranged in parallel between the branch waveguide Wg1 on the inner peripheral side of the folded parallel waveguide 18 and the branch waveguide Wg8 on the outer peripheral side of the folded parallel waveguide 18.

[0067] The optical modulator 1A has a first pitch P1, which indicates the pitch interval between the fourth branch waveguide 17A11 (Wg1) on the inner peripheral side and the fourth branch waveguide 17A11 (Wg8) on the outer peripheral side among the plurality of fourth branch waveguides 17A11 extending in parallel. The optical modulator 1A has a second pitch P2, which indicates the pitch interval between the folded-back parallel waveguide 18 (Wg1) on the inner peripheral side and the folded-back parallel waveguide 18 (Wg8) on the outer peripheral side among the plurality of folded-back parallel waveguides 18 extending in parallel. In addition, the optical modulator 1A has a third pitch P3, which indicates the pitch interval between the first parallel waveguide 17B (Wg1) on the inner peripheral side and the first parallel waveguide 17B (Wg8) on the outer peripheral side among the plurality of first parallel waveguides 17B extending in parallel.

[0068] When P1=P2=P3=0, there is no difference in waveguide length between the branch waveguides Wg1 to Wg8. That is, the difference between the waveguide length of the branch waveguide Wg1 on the inner circumference side and the waveguide length of the branch waveguide Wg8 on the outer circumference side is 0. In addition, when P1=P2=0 and P3>0, the difference between the waveguide length of the branch waveguide Wg1 on the inner circumference side and the waveguide length of the branch waveguide Wg8 on the outer circumference side is -P3. That is, the waveguide length of the branch waveguide Wg8 is longer than the waveguide length of the branch waveguide Wg1 by P3. In addition, when P1=P3=0 and P2>0, the difference between the waveguide length of the branch waveguide Wg1 on the inner circumference side and the waveguide length of the branch waveguide Wg8 on the outer circumference side is -2×P2. That is, the waveguide length of the branch waveguide Wg8 is longer than the waveguide length of the branch waveguide Wg1 by 2×P2. In addition, when P2=P3=0 and P1>0, the difference between the waveguide length of the branch waveguide Wg1 on the inner circumference side and the waveguide length of the branch waveguide Wg8 on the outer circumference side is P1. That is, the waveguide length of the branch waveguide Wg1 is longer than the waveguide length of the branch waveguide Wg8 by P1. Therefore, by setting P1=2×P2+P3, the waveguide length of the branch waveguide wg1 and the waveguide length of the branch waveguide wg8 can be made equal. The waveguide lengths of the other branch waveguides Wg2 to Wg7 can also be made equal by setting the same relationship. In addition, the condition that the folded parallel waveguide 18 is shortened and the electrode line 26 on the SiPh chip 2 can be shortened is P3>P2. In order to make the waveguide lengths of the branch waveguides Wg1 to Wg8 equal, set P1>P3.

[0069] Furthermore, in the optical modulator 1A, the fourth branch waveguide 17A11, the folded parallel waveguide 18, and the first parallel waveguide 17B are set so that the values ​​satisfy the relationship of P1>P3>P2. As a result, the waveguide lengths of the eight branch waveguides constituting the Mach-Zehnder interferometer become equal, so that even if the temperature changes, there is no phase difference of light between the waveguides in the branch waveguides, and the output of the signal light beam can be stabilized.

[0070] The second DC modulation unit 50A includes a second heater electrode 51A, which is arranged for each waveguide in the second front-stage branch waveguide 15A, and a direct current signal is applied to the second DC modulation unit 50A, and each second heater electrode 51A is arranged parallel to a direction substantially perpendicular to the first waveguide 11.

[0071] In the optical modulator 1A according to Embodiment 2, the fourth branch waveguide 17A11, the return parallel waveguide 18, and the first parallel waveguide 17B are set so that the relationship of P1>P3>P2 is satisfied between the values. As a result, the waveguide lengths of the eight branch waveguides Wg1 to Wg8 constituting the Mach-Zehnder interferometer become equal, so that even if the temperature changes, there is no phase difference of light between the waveguides in the branch waveguides, and the output of the signal light beam can be stabilized.

[0072] In addition, an example has been given in which the fourth branch waveguide 17A11, the folded parallel waveguide 18, and the first parallel waveguide 17B are arranged in the optical modulator 1A according to embodiment 2 so that the relationship of P1>P3>P2 is satisfied between the values. However, the present invention is not limited to this. As described above, the fourth branch waveguide 17A11, the folded parallel waveguide 18, and the first parallel waveguide 17B are arranged in the optical modulator 1A so as to satisfy the relationship of (P1=P2×2+P3). Even in this case, the waveguide lengths of the eight branch waveguides constituting the Mach-Zehnder interferometer become equal, so that even if the temperature changes, there is no phase difference of light between the waveguides in the branch waveguides, and the output of the signal light beam can be stabilized.

[0073] In the optical modulator 1A according to Embodiment 2, the second front-stage branch waveguide 15A between the second branch portion 14 and the third branch portion 16 is provided in a direction substantially perpendicular to the first waveguide 11, and the second heater electrode 51A in the second DC modulation unit 50A is provided on the second front-stage branch waveguide 15A. However, by providing the second heater electrode 51A on the second front-stage branch waveguide 15A, the chip size of the optical modulator 1A in the direction perpendicular to the first waveguide 11 becomes large. Therefore, an embodiment for dealing with such a situation will be described below as Embodiment 3.

[0074] Implementation 3

[0075] Figure 31 is a schematic plan view illustrating an example of an optical modulator 1B according to Embodiment 3. Note that the same components as those of the optical modulator 1A according to Embodiment 2 are denoted by the same reference numerals, and descriptions of duplicate components and operations will be omitted. The difference between the optical modulator 1B according to Embodiment 3 and the optical modulator 1A according to Embodiment 2 is that the second front-stage branch waveguide 15B is not arranged in a direction perpendicular to the first waveguide 11, but is arranged in a direction substantially parallel to the first waveguide 11. The optical modulator 1B includes a front-stage branch waveguide 60B between the first waveguide 11 and the first branch waveguide 17A1.

[0076] The front-stage branch waveguide 60B includes two first front-stage branch waveguides 13B connected to the first waveguide 11, and two second front-stage branch waveguides 15B connected to the first front-stage branch waveguide 13B. The front-stage branch waveguide 60B is a waveguide that is connected to the first waveguide 11 and changes the traveling direction of the first waveguide 11. The two first branch waveguides 17A1 connected to the second front-stage branch waveguide 15B are rear-stage branch waveguides that connect the front-stage branch waveguide 60B and the folded parallel waveguide 18 and return the traveling direction to the original traveling direction.

[0077] The first branch waveguide 17A1 includes a fourth branch waveguide 17A11 connected to the second preceding branch waveguide 15B and a curved parallel waveguide 17A12 having a curved structure connected to the fourth branch waveguide 17A11. The first branch waveguide 17A1 includes a parallel waveguide 17A13 connecting the curved parallel waveguide 17A12 and the folded parallel waveguide 18.

[0078] The second DC modulation unit 50B includes a second heater electrode 51B, which is arranged for each waveguide in the second front-stage branch waveguide 15B, and a direct current signal is applied to the second DC modulation unit 50B, and each second heater electrode 51B is arranged in parallel to a direction substantially parallel to the first waveguide 11.

[0079] In the optical modulator 1B according to Embodiment 3, each second heater electrode 51B of the second DC modulation unit 50B provided for each of the second front-stage branch waveguides 15B is provided in parallel to the direction substantially parallel to the first waveguide 11. As a result, the chip size of the optical modulator 1B in the direction perpendicular to the first waveguide 11 can be reduced.

[0080] Figure 4 is an explanatory diagram illustrating an example of the optical transceiver 70 according to the present embodiment. Figure 4The illustrated optical transceiver 70 is connected to the optical fiber on the output side and the optical fiber on the input side. The optical transceiver 70 includes a light source 71, a digital signal processor (DSP) 72, and an optical transmitter / receiver 73. The optical transmitter / receiver 73 includes an optical transmitter 73A and an optical receiver 73B. The DSP 72 is an electronic component that performs digital signal processing. For example, the DSP 72 performs processing such as encoding of transmission data, generates an electrical signal including transmission data, and outputs the generated electrical signal to the optical transmitter 73A. In addition, the DSP 72 obtains an electrical signal including received data from the optical receiver 73B, performs processing such as decoding of the acquired electrical signal, and obtains the received data.

[0081] The light source 71 includes, for example, a laser diode, etc., generates light of a predetermined wavelength, and supplies the light to the optical transmitter 73A and the optical receiver 73B. The optical transmitter 73A includes an optical modulator element 73A1, which modulates the light supplied from the light source 71 by an electrical signal output from the DSP 72, and outputs the modulated signal beam to the optical fiber.

[0082] The optical modulator element 73A1 includes: a first chip, which includes a first port and a second port; and a second chip, which is arranged on the first chip and has a material with an electro-optical effect higher than the electro-optical effect of the first chip. The first chip includes: a first waveguide, which is connected to the first port and propagates a signal light beam from the first port; and a first branch waveguide, which is connected to the first waveguide and has a branch structure for propagating the signal light beam from the first waveguide. The first chip includes: a folded parallel waveguide, which is connected to the first branch waveguide and has a folded structure; and a first parallel waveguide, which is connected to the folded parallel waveguide and propagates the signal light beam from the folded parallel waveguide. The first chip includes: a second waveguide, which is connected to the second port and propagates a signal light beam to the second port; and a second branch waveguide, which is connected to the second waveguide and has a branch structure for propagating a signal light beam to the second waveguide. The first chip includes a phase adjustment unit, which is arranged on the first branch waveguide and adjusts the phase of the signal light beam propagating through the first branch waveguide according to a direct current signal. The second chip includes a second parallel waveguide, which is connected to the first parallel waveguide on a first end face and is connected to the second branch waveguide on a second end face different from the first end face. The second parallel waveguide propagates a signal light beam from the first parallel waveguide to the second branch waveguide. The second chip includes a phase adjustment unit, which is arranged on the second parallel waveguide and modulates the phase of the signal light beam propagating through the second parallel waveguide according to the high-frequency signal.

[0083] When the light supplied from the light source 71 propagates through the waveguide, the optical transmitter 73A generates a signal light beam by modulating the light using an electrical signal. The optical receiver 73B includes an optical receiver element 73B1 that receives the light received from the optical fiber, converts the received light into an electrical signal using the light supplied from the light source 71, and outputs the converted electrical signal to the DSP 72.

[0084] Although the case where the optical transmitter 73A and the optical receiver 73B are built in the optical transceiver 70 has been exemplified, the present invention can also be applied to an optical transmitter including only the built-in optical transmitter 73A, which includes a built-in optical device. In addition, the optical device is applicable not only to the optical transceiver 70 but also to the optical transmitter / receiver 73.

[0085] It should be noted that, for the sake of convenience of description, a case has been exemplified in which, in the optical modulator 1 according to the embodiment, an arrangement is made to realize a route of the first port 2B→the first waveguide 11→the second DC modulation unit 50→the first DC modulation unit 40→the folded-back parallel waveguide 18→the RF modulation unit 30 of the thin film LN chip 3→the PBC 25→the second port 2C. However, the present disclosure is not limited thereto, and an arrangement may be made to realize a route of the first port 2B→the first waveguide 11→the RF modulation unit 30 of the thin film LN chip 3→the folded-back parallel waveguide 18→the first DC modulation unit 40→the second DC modulation unit 50→the PBC 25→the second port 2C.

[0086] In addition, although the case where the phase adjustment unit is configured as the first DC modulation unit 40 and the second DC modulation unit 50 has been exemplified, the phase adjustment unit is not limited thereto, and may be any one of the first DC modulation unit 40 and the second DC modulation unit 50, and may be appropriately changed. In addition, the case where the first DC modulation unit 40 and the second DC modulation unit 50 use the heater electrode has been exemplified, an electrode to which a bias voltage is applied may be used, and the electrode may be appropriately changed.

[0087] Although a thin film LN chip is exemplified in this embodiment, the present invention is not limited thereto, and for example, TF-barium titanate may be used, and the material may be appropriately changed. The material of the electro-optical effect may be, for example, TF-BTO (BaTiO3), TF-PLZT (PbLaZrTiO3), or TF-PZT (PbZrTiO3), and may be appropriately changed.

[0088] In the present embodiment, the material of the electrode wire is not limited to Al, Au, Cu, etc., and can be changed appropriately.

[0089] According to one aspect, an optical device or the like having a miniaturized chip size can be provided.

Claims

1. An optical device, comprising: A first chip, the first chip comprising a first port and a second port; as well as a second chip, the second chip being disposed on the first chip and having a material having an electro-optical effect higher than that of the first chip, wherein: The first chip comprises: a first waveguide connected to the first port and transmitting a signal light beam from the first port; a first branch waveguide connected to the first waveguide and having a branch structure for propagating a signal light beam from the first waveguide; a folded parallel waveguide, the folded parallel waveguide is connected to the first branch waveguide and has a folded structure; a first parallel waveguide connected to the folded parallel waveguide and transmitting a signal light beam from the folded parallel waveguide; a second waveguide connected to the second port and propagating the signal light beam toward the second port; a second branch waveguide connected to the second waveguide and having a branch structure for propagating the signal light beam toward the second waveguide; and a phase adjuster, the phase adjuster being arranged on the first branch waveguide and adjusting the phase of the signal light beam propagating through the first branch waveguide according to a direct current signal, and The second chip comprises: a second parallel waveguide, which is connected to the first parallel waveguide on a first end face, is connected to the second branch waveguide on a second end face different from the first end face, and propagates the signal light beam from the first parallel waveguide to the second branch waveguide; and A phase modulator is provided on the second parallel waveguide and modulates the phase of the signal light beam propagating through the second parallel waveguide according to a high-frequency signal.

2. The optical device according to claim 1, wherein: The first chip comprises: An electrode line is arranged parallel to the first parallel waveguide and electrically connects the electrode in the phase modulator and a driver circuit.

3. The optical device according to claim 1, wherein: The first branch waveguide comprises: a front-stage branch waveguide connected to the first waveguide and changing a traveling direction of the first waveguide; and A rear-stage branch waveguide connects the front-stage branch waveguide and the folded-back parallel waveguide and returns the traveling direction to the original traveling direction.

4. The optical device according to claim 3, wherein: The front-stage branch waveguide comprises: a plurality of first front-stage branch waveguides, the plurality of first front-stage branch waveguides being connected to the first waveguide; and a second front-stage branch waveguide, wherein the second front-stage branch waveguide is connected to the first front-stage branch waveguide, The rear-stage branch waveguide comprises: a fourth branch waveguide connected to each of the second front-stage branch waveguides; and A parallel waveguide connected between the fourth branch waveguide and the folded parallel waveguide, and comprising: a first pitch indicating a pitch interval between fourth branch waveguides at both ends among the plurality of fourth branch waveguides extending in parallel; a second pitch indicating a pitch interval between the turned-back parallel waveguides at both ends among the plurality of the turned-back parallel waveguides extending in parallel; and a third pitch indicating a pitch interval between first parallel waveguides at both ends among the plurality of first parallel waveguides extending in parallel, and The first pitch, the second pitch, and the third pitch satisfy the following relationship: the first pitch>the third pitch>the second pitch.

5. The optical device according to claim 3, wherein: The front-stage branch waveguide comprises: a plurality of first front-stage branch waveguides, the plurality of first front-stage branch waveguides being connected to the first waveguide; and a second front-stage branch waveguide, wherein the second front-stage branch waveguide is connected to the first front-stage branch waveguide, The rear-stage branch waveguide comprises: a fourth branch waveguide connected to each of the second front-stage branch waveguides; and A parallel waveguide connected between the fourth branch waveguide and the folded parallel waveguide, and comprising: a first pitch indicating a pitch interval between fourth branch waveguides at both ends among the plurality of fourth branch waveguides extending in parallel; a second pitch indicating a pitch interval between the turned-back parallel waveguides at both ends among the plurality of the turned-back parallel waveguides extending in parallel; and a third pitch indicating a pitch interval between first parallel waveguides at both ends among the plurality of first parallel waveguides extending in parallel, and The first pitch, the second pitch, and the third pitch satisfy the following relationship: the first pitch=the second pitch×2+the third pitch.

6. The optical device according to claim 4 or 5, wherein: The phase adjuster comprises: An electrode is arranged on each waveguide of the second front-stage branch waveguide and applies the DC signal to the phase adjuster, and each electrode is arranged parallel to a direction substantially perpendicular to the first waveguide.

7. The optical device according to claim 4 or 5, wherein: The second front-stage branch waveguide is arranged substantially parallel to the first waveguide, and The phase adjuster comprises: An electrode is arranged on each waveguide of the second front-stage branch waveguide and applies the DC signal to the phase adjuster, and each electrode is arranged in parallel with a direction substantially parallel to the first waveguide.

8. An optical transmitter, comprising: a light source that emits light; as well as a light modulator element, wherein the light modulator element modulates the light from the light source according to an electrical signal, The light modulator element comprises: A first chip, the first chip comprising a first port and a second port; and a second chip, the second chip being disposed on the first chip and having a material having an electro-optical effect higher than that of the first chip, The first chip comprises: a first waveguide connected to the first port and transmitting a signal light beam from the first port; a first branch waveguide connected to the first waveguide and having a branch structure for propagating a signal light beam from the first waveguide; a folded parallel waveguide, the folded parallel waveguide is connected to the first branch waveguide and has a folded structure; a first parallel waveguide connected to the folded parallel waveguide and transmitting a signal light beam from the folded parallel waveguide; a second waveguide connected to the second port and propagating the signal light beam toward the second port; a second branch waveguide connected to the second waveguide and having a branch structure for propagating the signal light beam toward the second waveguide; and a phase adjuster, the phase adjuster being arranged on the first branch waveguide and adjusting the phase of the signal light beam propagating through the first branch waveguide according to a direct current signal, and The second chip comprises: a second parallel waveguide, which is connected to the first parallel waveguide on a first end face, is connected to the second branch waveguide on a second end face different from the first end face, and propagates the signal light beam from the first parallel waveguide to the second branch waveguide; and A phase modulator is provided on the second parallel waveguide and modulates the phase of the signal light beam propagating through the second parallel waveguide according to a high-frequency signal.

9. An optical transceiver, comprising: a processor that performs signal processing on the electrical signal; a light source that generates light; an optical transmitter that modulates the light generated from the light source using an electrical signal output from the processor; as well as an optical receiver that uses the light generated from the light source to convert the received light into an electrical signal, wherein The optical transmitter comprises: A first chip, the first chip comprising a first port and a second port; and a second chip, the second chip being disposed on the first chip and having a material having an electro-optical effect higher than that of the first chip, The first chip comprises: a first waveguide connected to the first port and transmitting a signal light beam from the first port; a first branch waveguide connected to the first waveguide and having a branch structure for propagating a signal light beam from the first waveguide; a folded parallel waveguide, the folded parallel waveguide is connected to the first branch waveguide and has a folded structure; a first parallel waveguide connected to the folded parallel waveguide and transmitting a signal light beam from the folded parallel waveguide; a second waveguide connected to the second port and propagating the signal light beam toward the second port; a second branch waveguide connected to the second waveguide and having a branch structure for propagating the signal light beam toward the second waveguide; and a phase adjuster, the phase adjuster being arranged on the first branch waveguide and adjusting the phase of the signal light beam propagating through the first branch waveguide according to a direct current signal, and The second chip comprises: a second parallel waveguide, which is connected to the first parallel waveguide on a first end face, is connected to the second branch waveguide on a second end face different from the first end face, and propagates the signal light beam from the first parallel waveguide to the second branch waveguide; and A phase modulator is provided on the second parallel waveguide and modulates the phase of the signal light beam propagating through the second parallel waveguide according to a high-frequency signal.

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