# US 5,710,847 A · Semiconductor optical functional device

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- Number: US 5,710,847 A
- Document ID: US5710847A
- Status: Granted
- Kind: A
- Application number: 08/593,051
- Filed: 1996-01-29
- Granted: 1998-01-20
- Earliest claimed: 1995-02-03
- Assignees: Hitachi, Ltd.
- Inventors: Hideaki Takano; Hirohisa Sano; Tatsuo Kanetake; Masaki Ohira; Makoto Suzuki; Hiroaki Inoue
- Web page: https://patentgrep.com/patent/US5710847A

## CPC

- H01S 5/10: Construction or shape of the optical resonator {, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region (H01S5/20 takes precedence)}
- G02B 6/12004: {Combinations of two or more optical elements}
- G02B 6/14: Mode converters
- G02B 6/305: {and having an integrated mode-size expanding section, e.g. tapered waveguide}
- G02B 6/4207: {with optical elements reducing the sensitivity to optical feedback (anti-reflection devices specially adapted for lasers, see H01S3/0064)}
- G02B 6/1228: {Tapered waveguides, e.g. integrated spot-size transformers (for coupling with fibres G02B6/305)}
- G02B 2006/12121: {Laser}
- G02B 2006/12145: {Switch}
- G02B 2006/12195: {Tapering}
- H01S 5/1064: {varying width along the optical axis}
- H01S 5/1082: {with a special facet structure, e.g. structured, non planar, oblique}
- H01S 5/1085: {Oblique facets}
- H01S 5/2077: {using lateral bandgap control during growth, e.g. selective growth, mask induced}
- H01S 5/50: Amplifier structures not provided for in groups H01S5/02 - H01S5/30
- 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
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

To obtain an optical functional device such that the reflectivity of a facet and the loss of coupling with a fiber are reduced, a mode conversion region for changing the beam spot size is formed on the input facet and/or the output facet in an optical function region and the facet of the side to be connected with a fiber in the mode conversion region is formed obliquely to the direction of propagation of light.

## Claims

### Claim 1

A semiconductor optical functional device comprising:
an optical functional region; and
a mode conversion region for increasing a beam size of propagated light on a facet in said optical functional region;
wherein the facet of the side to be connected with a fiber in the mode conversion region is provided obliquely to the direction of propagation of light; and
wherein said mode conversion region includes a waveguide and is formed so as to gradually change the size of said waveguide in the direction of propagation of light.

### Claim 2 (depends on 1)

The semiconductor optical functional device according to claim 1, wherein a guide layer with a band gap wavelength smaller than that of an active layer is formed nearby the active layer which is a part of a layer constituting the optical functional region and the mode conversion region.

### Claim 3 (depends on 1)

A semiconductor optical functional device according to claim 1, wherein the mode conversion region is connected with a bend waveguide.

### Claim 4 (depends on 3)

The semiconductor optical functional device according to claim 3, wherein a guide layer with a band gap wavelength smaller than that of an active layer is formed nearby the active layer which is a part of a layer constituting the optical functional region, bend waveguide, and mode conversion region.

### Claim 5 (depends on 1)

The semiconductor optical functional device according to claim 1, wherein the mode conversion region is formed so as to gradually increase the size of said waveguide in the direction of propagation of light.

### Claim 6 (depends on 1)

The semiconductor optical functional device according to claim 1, wherein the waveguide is a multilayer structure waveguide and the size of the waveguide in its horizontal direction is gradually changed in the direction of propagation of light.

### Claim 7 (depends on 1)

The semiconductor optical functional device according to claim 1, wherein the waveguide is a multilayer structure waveguide and the size of the waveguide in its lateral direction to the layer is gradually changed in the direction of propagation of light.

### Claim 8 (depends on 1)

The semiconductor optical functional device according to claim 1, wherein the waveguide is a multilayer structure waveguide and both the sizes of the waveguide in its horizontal and lateral direction to the layer are gradually changed in the direction of propagation of light.

### Claim 9 (depends on 1, 2, 3, 4, 5, 6, 7, 8)

The semiconductor optical functional device according to any one of claims 1 to 8, wherein the optical functional region is constituted so as to function as an optical amplifier.

### Claim 10 (depends on 1, 2, 3, 4, 5, 6, 7, 8)

The semiconductor optical functional device according to any one of claims 1 to 8, wherein the optical functional region is constituted so as to function as a semiconductor laser.

### Claim 11 (depends on 1, 2, 3, 4, 5, 6, 7, 8)

The semiconductor optical functional device according to any one of claims 1 to 8, wherein the optical functional region is constituted so as to function as a waveguide-type optical switch having a plurality of waveguides and the mode conversion region is formed on each of the waveguides.

### Claim 12 (depends on 11)

The semiconductor optical functional device according to claim 11, wherein the beam divergence angle of the mode conversion region formed on each of the waveguides is different for each waveguide.

### Claim 13 (depends on 1, 2, 3, 4, 5, 6, 7, 8)

The semiconductor optical functional device according to any one of claims 1 to 8, wherein a carrier-injection structure is formed in the mode conversion region.