# US 8,787,420 B2 · Integrated semiconductor laser element

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- Number: US 8,787,420 B2
- Document ID: US8787420B2
- Status: Granted
- Kind: B2
- Application number: 13/960,429
- Filed: 2013-08-06
- Published: 2013-11-28
- Granted: 2014-07-22
- Earliest claimed: 2011-11-07
- Assignees: Furukawa Electric Co., Ltd.
- Applicants: Furukawa Electric Co., Ltd.
- Inventors: Tatsuya Kimoto; Go Kobayashi; Toshikazu Mukaihara
- Web page: https://patentgrep.com/patent/US8787420B2

## CPC

- H01S 5/4087: {emitting more than one wavelength}
- B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals
- H01S 5/1039: {Details on the cavity length}
- H01S 5/12: the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers (comprising a photonic bandgap structure H01S5/11; surface-emitting lasers H01S5/18)
- H01S 5/227: Buried mesa structure {; Striped active layer}
- H01S 5/50: Amplifier structures not provided for in groups H01S5/02 - H01S5/30
- H01S 5/026: Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers (stabilisation of output H01S5/06)
- H01S 5/0265: {Intensity modulators (intra-cavity modulators H01S5/0625)}
- H01S 5/2222: {having special electric properties}
- H01S 5/34306: {emitting light at a wavelength longer than 1000nm, e.g. InP based 1300 and 1500nm lasers}
- 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
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

Integrated are: semiconductor lasers of distributed feedback type that oscillate in single mode at emission wavelengths different from one another; a coupler that has as many input ports as the semiconductor lasers, the input ports to which output light from the semiconductor lasers are input, the coupler guiding and outputting the output light; and an amplifier that amplifies the output light from the coupler, and a predetermined relation holds true, where “N” is the number of the semiconductor lasers, “Ldfb” is a cavity length of each of the semiconductor lasers, “Δν0” is a spectral linewidth of laser light output therefrom, “Lsoa” is an amplifier length of the amplifier, “A” is an amplification factor of the amplifier, “Δν” is a spectral linewidth of amplified laser light output therefrom, and “R” is Δν/Δν0.

## Claims

### Claim 1

An integrated semiconductor laser element, comprising and integrated of:
a plurality of semiconductor lasers of distributed feedback type that oscillate in single mode at emission wavelengths different from each other;
an optical coupler that has as many input ports as the plurality of semiconductor lasers, the input ports to which output light from the plurality of semiconductor lasers are input, the optical coupler guiding and outputting the output light; and
a semiconductor optical amplifier that amplifies the output light from the optical coupler,
wherein the following relation (1) holds true, where “N” is the number of the plurality of semiconductor lasers, “Ldfb” is a cavity length of each of the plurality of semiconductor lasers, “Δν0” is a spectral linewidth of laser light output therefrom, “Lsoa” is an amplifier length of the semiconductor optical amplifier, “A” is an amplification factor of the semiconductor optical amplifier, “Δν” is a spectral linewidth of amplified laser light output therefrom, and “R” is Δν/Δν0:
Lsoa
Ldfb
≤
(
R
-
1
)
·
N
·
1.44
·
A
-
0.74
.
(
1
)

### Claim 2 (depends on 1)

The integrated semiconductor laser element according to claim 1, wherein in each of the plurality of semiconductor lasers,
a value of a product of a coupling coefficient of a diffraction grating in the each of the plurality of semiconductor lasers and the cavity length is set so that the spectral linewidth of the output light from the each of the plurality of semiconductor lasers becomes 250 kHz or less, and
“R” is 2.

### Claim 3 (depends on 1)

The integrated semiconductor laser element according to claim 1, wherein the cavity length of each of the plurality of semiconductor lasers is 1200 micrometers or greater.

### Claim 4 (depends on 1)

The integrated semiconductor laser element according to claim 1, wherein a product of a coupling coefficient of a diffraction grating in each of the plurality of semiconductor lasers and the cavity length is approximately 1.5.

### Claim 5 (depends on 1)

The integrated semiconductor laser element according to claim 1, wherein an intensity of the output light from the semiconductor optical amplifier is 50 milliwatts or greater.