# US 11,451,302 B2 · Transmitter optical subassembly and optical module > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,451,302 B2 - Document ID: US11451302B2 - Status: Granted - Kind: B2 - Application number: 16/214,332 - Filed: 2018-12-10 - Published: 2019-06-20 - Granted: 2022-09-20 - Earliest claimed: 2017-12-18 - Assignees: Lumentum Japan, Inc. - Applicants: Lumentum Japan, Inc. - Inventors: Yoshihiro Nakai; Atsushi Nakamura; Hideaki Asakura - Web page: https://patentgrep.com/patent/US11451302B2 ## CPC - H04B 10/516: Details of coding or modulation - G02F 1/0121: {Operation of devices; Circuit arrangements, not otherwise provided for in this subclass} - G02F 1/0157: {using electro-absorption effects, e.g. Franz-Keldysh [FK] effect or quantum confined stark effect [QCSE]} - G02F 1/17: based on variable-absorption elements not provided for in groups G02F1/015 - G02F1/169 - H04B 10/40: Transceivers - H04B 10/504: {using direct modulation} - H04B 10/588: in external modulation systems - H04B: TRANSMISSION - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS ## Abstract A transmitter optical subassembly may include an optical modulator for modulating output light from the light source. The optical modulator has a characteristic that a current depending on amount of optical absorption has a positive correlation with an applied voltage thereto. The transistor at the second terminal is connected in series to the optical modulator. A drive voltage applied to the optical modulator and the transistor is divided into a first voltage applied to the optical modulator and a second voltage applied to the transistor. A drive current flowing through the optical modulator and the transistor depends on the control signal input to the first terminal. The first voltage is based on the drive current and is subject to the characteristic of the optical modulator. The second voltage fluctuates in response to the first voltage. ## Claims ### Claim 1 A transmitter optical subassembly comprising: a light source; an optical modulator for modulating output light from the light source, the optical modulator having a characteristic that a current depending on an amount of optical absorption has a positive correlation with an applied voltage thereto; a transistor with a first terminal, a second terminal, and a third terminal, configured to pass a current between the second terminal and the third terminal based on a control signal input to the first terminal, wherein the transistor at the second terminal is connected in series to the optical modulator, a drive voltage applied to the optical modulator and the transistor is divided into a first voltage applied to the optical modulator and a second voltage applied to the transistor, a drive current flowing through the optical modulator and the transistor depends on the control signal input to the first terminal, the first voltage is based on the drive current and is subject to the characteristic of the optical modulator, and the second voltage fluctuates based on the first voltage; and a package that houses a submount, wherein the optical modulator and the transistor are mounted on the submount, and wherein the third terminal is adjacent to the optical modulator. ### Claim 2 (depends on 1) The transmitter optical subassembly according to claim 1, wherein the transistor is a field-effect transistor, and the control signal is a voltage signal. ### Claim 3 (depends on 1) The transmitter optical subassembly according to claim 1, wherein the light source is also mounted on the submount. ### Claim 4 (depends on 1) The transmitter optical subassembly according to claim 1, wherein the light source and the optical modulator are monolithically integrated. ### Claim 5 (depends on 1) The transmitter optical subassembly according to claim 1, wherein the package is made of material that is different than a material of the submount. ### Claim 6 An optical module comprising; a receiver optical subassembly; and a transmitter optical subassembly comprising: a light source; an optical modulator for modulating output light from the light source; a transistor with a first terminal, a second terminal, and a third terminal, configured to pass a current between the second terminal and the third terminal based on a control signal input to the first terminal, wherein the transistor at the second terminal is connected in series to the optical modulator; and a package that houses a submount, wherein the light source, the optical modulator, and the transistor are mounted on the submount, and wherein the third terminal is adjacent to the optical modulator. ### Claim 7 (depends on 6) The optical module according to claim 6, wherein the transistor is an n-type metal-oxide-semiconductor field-effect transistor. ### Claim 8 (depends on 6) The optical module according to claim 6, wherein the light source and the optical modulator are monolithically integrated. ### Claim 9 (depends on 6) The optical module according to claim 6, wherein the control signal is a voltage signal. ### Claim 10 (depends on 6) The optical module according to claim 6, wherein the package is made of a material that is different than a material of the submount. ### Claim 11 (depends on 6) The optical module according to claim 6, wherein the submount includes a light source power line formed thereon for providing a light source power source to the light source. ### Claim 12 (depends on 11) The optical module according to claim 11, wherein the third terminal is arranged between the light source power line and the second terminal. ### Claim 13 A transmitter optical subassembly comprising: a light source; an optical modulator for modulating output light from the light source; a transistor with a first terminal, a second terminal, and a third terminal, configured to pass a current between the second terminal and the third terminal based on a control signal input to the first terminal, wherein the transistor at the second terminal is connected in series to the optical modulator; and a package that houses a submount, wherein the light source, the optical modulator, and the transistor are mounted on the submount, and wherein the third terminal is adjacent to the optical modulator. ### Claim 14 (depends on 13) The transmitter optical subassembly according to claim 13, wherein a drive voltage applied to the optical modulator and the transistor is divided into a first voltage applied to the optical modulator and a second voltage applied to the transistor, a drive current flowing through the optical modulator and the transistor depends on the control signal input to the first terminal, the first voltage is based on the drive current, and the second voltage fluctuates based on the first voltage. ### Claim 15 (depends on 13) The transmitter optical subassembly according to claim 13, wherein the light source is a laser diode, the optical modulator is an electro-absorption optical modulator, and the transistor is a field-effect transistor. ### Claim 16 (depends on 15) The transmitter optical subassembly according to claim 15, wherein the laser diode and the electro-absorption optical modulator are integrated into an electro-absorption optical modulator integrated laser. ### Claim 17 (depends on 13) The transmitter optical subassembly according to claim 13, wherein the control signal is a voltage signal. ### Claim 18 (depends on 13) The transmitter optical subassembly according to claim 13, wherein the light source and the optical modulator are monolithically integrated. ### Claim 19 (depends on 13) The transmitter optical subassembly according to claim 13, wherein the package is made of a material that is different than a material of the submount. ### Claim 20 (depends on 13) The transmitter optical subassembly according to claim 13, wherein the submount includes a light source power line formed thereon for providing a light source power source to the light source, and wherein the third terminal is arranged between the light source power line and the second terminal.