# US 2021/0242658 A1 · Optical semiconductor device and control method of the same

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- Number: US 2021/0242658 A1
- Document ID: US20210242658A1
- Status: Published application
- Kind: A1
- Application number: 17/049,512
- Filed: 2019-04-23
- Published: 2021-08-05
- Earliest claimed: 2018-04-26
- Assignees: Sumitomo Electric Device Innovations, Inc.
- Applicants: Sumitomo Electric Device Innovations, Inc.
- Inventors: Hiromitsu KAWAMURA
- Web page: https://patentgrep.com/patent/US20210242658A1

## CPC

- H01S 5/0239: Combinations of electrical or optical elements
- H01S 5/0687: Stabilising the frequency of the laser
- H01S 5/0071: {for beam steering, e.g. using a mirror outside the cavity to change the beam direction}
- H01S 5/141: {using a wavelength selective device, e.g. a grating or etalon (H01S5/146 takes precedence)}
- H01S 5/02208: characterised by the shape of the housings
- H01S 5/02325: Mechanically integrated components on mount members or optical micro-benches
- H01S 5/02415: {by using a thermo-electric cooler [TEC], e.g. Peltier element}
- H01S 5/02438: {Characterized by cooling of elements other than the laser chip, e.g. an optical element being part of an external cavity or a collimating lens}
- H01S 5/0261: {Non-optical elements, e.g. laser driver components, heaters (H01S5/0265 takes precedence)}
- H01S 5/0617: {using memorised or pre-programmed laser characteristics}
- H01S 5/0683: by monitoring the optical output parameters
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL

## Abstract

Provided is an optical semiconductor device including: a wavelength tunable laser element; a beam splitter that splits an outgoing beam of the wavelength tunable laser element into a first light beam and a second light beam parallel to each other, and outputs the first light beam and the second light beam; and an etalon that transmits the first light beam and the second light beam, wherein an optical path length to the first light beam of the etalon is different from an optical path length to the second light beam of the etalon.

## Claims

### Claim 1

An optical semiconductor device comprising:
a wavelength tunable laser element;
a beam splitter that splits an outgoing beam of the wavelength tunable laser element into a first light beam and a second light beam parallel to each other, and outputs the first light beam and the second light beam; and
an etalon that transmits the first light beam and the second light beam, wherein
an optical path length to the first light beam of the etalon is different from an optical path length to the second light beam of the etalon.

### Claim 2 (depends on 1)

The optical semiconductor device according to claim 1, wherein
the etalon includes a first part that determines the optical path length to the first light beam, and a second part that determines the optical path length to the second light beam, and
a thickness of the first part is different from a thickness of the second part.

### Claim 3

An optical semiconductor device comprising:
a wavelength tunable laser element;
a beam splitter that splits an outgoing beam of the wavelength tunable laser element into a first light beam and a second light beam, and outputs the first light beam and the second light beam; and
an etalon that transmits the first light beam and the second light beam, wherein
the first light beam enters the etalon from a first direction, and forms a first optical path in the etalon,
the second light beam enters the etalon from a second direction different from the first direction, and forms a second optical path in the etalon, and
an optical path length of the first optical path is different from an optical path length of the second optical path.

### Claim 4 (depends on 3)

The optical semiconductor device according to claim 3, wherein
the beam splitter includes a first reflecting surface and a second reflecting surface, and
the first reflecting surface outputs, as the first light beam, a part of the outgoing beam in the first direction, and the second reflecting surface outputs, as the second light beam, another part of the outgoing beam in the second direction.

### Claim 5

An optical semiconductor device comprising:
a wavelength tunable laser element;
a beam splitter that splits an outgoing beam of the wavelength tunable laser element into a first light beam and a second light beam, and outputs the first light beam and the second light beam;
a polarizer that makes a polarization state of one of the first light beam and the second light beam different from a polarization state of the other of the first light beam and the second light beam by changing a polarization state of at least one of the first light beam and the second light beam; and
an etalon that transmits the first light beam and the second light beam that have passed through the polarizer, wherein
the etalon is composed of a material that has a refractive index unique to a polarization state of a light beam entering the etalon.

### Claim 6 (depends on 5)

The optical semiconductor device according to claim 5, wherein
the polarizer includes a first polarizer and a second polarizer, and
the first polarizer changes a polarization state of the first light beam, the second polarizer changes a polarization state of the second light beam to a polarization state different from that of the first light beam.

### Claim 7 (depends on 5)

The optical semiconductor device according to claim 5,
wherein the beam splitter includes a reflecting surface that reflects the outgoing beam, and
the polarizer is provided on the reflecting surface.

### Claim 8 (depends on 3)

The optical semiconductor device according to claim 3, wherein
the etalon has a uniform thickness

### Claim 9 (depends on 1)

The optical semiconductor device according to claim 1, wherein
the beam splitter includes a first reflecting surface that directs the outgoing beam toward a first axis and outputs the first light beam, and a second reflecting surface that directs the outgoing beam toward a second axis and outputs the second light beam, and
the first axis and the second axis are parallel to each other, and are different from an optical axis of the outgoing beam.

### Claim 10 (depends on 7)

The optical semiconductor device according to claim 7, wherein
the reflecting surface transmits a part of the outgoing beam to output a third light beam.

### Claim 11

A control method of an optical semiconductor device, the optical semiconductor device including a wavelength tunable laser element, a beam splitter that splits an outgoing beam of the wavelength tunable laser element into a first light beam and a second light beam parallel to each other and outputs the first light beam and the second light beam, an etalon that transmits the first light beam and the second light beam, a first detection unit that receives the first light beam that has passed through the etalon, a second detection unit that receives a second light beam that has passed through the etalon, and a third detection unit that receives another second light beam before passing through the etalon, wherein
an optical path length to the first light beam of the etalon is different from an optical path length to the second light beam of the etalon, and
the control method includes:
a step of driving the wavelength tunable laser element in a driving condition corresponding to a target wavelength of the outgoing beam of the wavelength tunable laser element, and
a step of selecting a target wavelength with use of a detection result of one of the first detection unit and the second detection unit and a detection result of the third detection unit.

### Claim 12 (depends on 11)

The control method of the optical semiconductor device according to claim 11, wherein
the optical semiconductor device further includes a memory that stores driving information of the wavelength tunable laser element, and
the step of selecting the target wavelength includes a step of selecting, based on the target wavelength, which of the detection result of the first detection unit and the detection result of the second detection unit stored in the memory is to be used.