US5539766A
Expired / Lapsed
US
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Distributed feedback semiconductor laser
Assignee: Panasonic Holdings Corp
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Filing: 1994-08-18
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Granted: 1996-07-23
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Expires: 2014-08-18
Abstract
Abstract A distributed feedback semiconductor laser which includes a semiconductor substrate of a first conductive type; a semiconductor multi-layer structure provided on the semiconductor substrate and including an active layer for generating laser light; and a gain-coupled diffraction grating provided between the semiconductor substrate and the semiconductor multi-layer structure. The diffraction grating includes a plurality of curved projections periodically arranged at a surface of the semiconductor substrate and a quantum well light absorption layer for covering the plurality of curved projections. The quantum well light absorption layer includes a light absorption area having a first thickness at each border between two adjacent curved projections and a non-light absorption area having a second thickness which is smaller than the first thickness at a top of each of the curved projections. The light absorption area has a band gap which is narrower than a band gap of the active layer, and the non-light absorption area has a band gap which is wider than the band gap of the active layer.
Inventors
- 👤 Masato Ishino
- 👤 Masahiro Kitoh
- 👤 Nobuyuki Otsuka
- 👤 Yasushi Matsui
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:33
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/10; H01S5/12; H01S5/1228; B; B82; B82Y; B82Y20/00; H01S5/20; H01S5/2004; H01S5/2018; H01S5/2022; H01S5/30; H01S5/34; H01S5/3403; H01S5/3428; H01S5/343; H01S5/3434; Y; Y10; Y10S; Y10S148/00; Y10S148/095
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
168 words
A distributed feedback semiconductor laser, comprising: a semiconductor substrate of a first conductive type; a semiconductor multi-layer structure provided on the semiconductor substrate and including an active layer for generating laser light; and a gain-coupled diffraction grating provided between the semiconductor substrate and the semiconductor multi-layer structure, wherein: the diffraction grating includes a plurality of curved projections periodically arranged at a surface of the semiconductor substrate and a quantum well light absorption layer for covering the plurality of curved projections, the quantum well light absorption layer includes a light absorption area having a first thickness at each border between two adjacent curved projections and a non-light absorption area having a second thickness which is smaller than the first thickness at a top of each of the curved projections, and the light absorption area has a band gap which is narrower than a band gap of the active layer, and the non-light absorption area has a band gap which is wider than the band gap of the active layer.
Claim 2
Dependent Claim
168 words
A distributed feedback semiconductor laser, comprising: a semiconductor substrate of a first conductive type; a semiconductor multi-layer structure provided on the semiconductor substrate and including an active layer for generating laser light; and a gain-coupled diffraction grating provided between the semiconductor substrate and the semiconductor multi-layer structure, wherein: the diffraction grating includes a plurality of curved projections periodically arranged at a surface of the semiconductor substrate and a quantum well light absorption layer for covering the plurality of curved projections, the quantum well light absorption layer includes a light absorption area having a first thickness at each border between two adjacent curved projections and a non-light absorption area having a second thickness which is smaller than the first thickness at a top of each of the curved projections, and the light absorption area has a band gap which is narrower than a band gap of the active layer, and the non-light absorption area has a band gap which is wider than the band gap of the active layer.
Claim 3
Dependent Claim
26 words
A distributed feedback semiconductor laser according to claim 1, wherein the thickness of the quantum well light absorption layer changes periodically and nonlinearly along a cavity.
Claim 4
Dependent Claim
54 words
A distributed feedback semiconductor laser according to claim 2, wherein the semiconductor multi-layer structure includes: an optical waveguide layer of the first conductivity type provided between the active layer and the diffraction grating; and a cladding layer of a second conductivity type located farther from the semiconductor substrate than the active layer is located.
Claim 5
Dependent Claim
18 words
A distributed feedback semiconductor laser according to claim 1, wherein the active layer has a quantum well structure.
Claim 6
Dependent Claim
19 words
A distributed feedback semiconductor laser according to claim 1, wherein the active layer has a strained quantum well structure.
Claim 7
Dependent Claim
213 words
A distributed feedback semiconductor laser, comprising: a semiconductor substrate of a first conductivity type; a semiconductor multi-layer structure provided on the semiconductor substrate and including an active layer for generating laser light; and a gain-coupled diffraction grating provided between the semiconductor substrate and the semiconductor multi-layer structure, wherein: the diffraction grating includes: a first semiconductor layer provided on the semiconductor substrate; a plurality of projections periodically arranged at a surface of the first semiconductor layer; a quantum well light absorption layer for covering the plurality of projections; and a second semiconductor layer provided on the quantum well light absorption layer and having a substantially smooth top surface, the quantum well light absorption layer includes a light absorption area having a first thickness at each border between two adjacent projections and a non-light absorption area having a second thickness which is smaller than the first thickness at a top of each of the projections, the light absorption area has a band gap which is narrower than a band gap of the active layer, and the non-light absorption area has a band gap which is wider than the band gap of the active layer, and the first semiconductor layer has a band gap which is narrower than a band gap of the second semiconductor layer.
Claim 8
Dependent Claim
213 words
A distributed feedback semiconductor laser, comprising: a semiconductor substrate of a first conductivity type; a semiconductor multi-layer structure provided on the semiconductor substrate and including an active layer for generating laser light; and a gain-coupled diffraction grating provided between the semiconductor substrate and the semiconductor multi-layer structure, wherein: the diffraction grating includes: a first semiconductor layer provided on the semiconductor substrate; a plurality of projections periodically arranged at a surface of the first semiconductor layer; a quantum well light absorption layer for covering the plurality of projections; and a second semiconductor layer provided on the quantum well light absorption layer and having a substantially smooth top surface, the quantum well light absorption layer includes a light absorption area having a first thickness at each border between two adjacent projections and a non-light absorption area having a second thickness which is smaller than the first thickness at a top of each of the projections, the light absorption area has a band gap which is narrower than a band gap of the active layer, and the non-light absorption area has a band gap which is wider than the band gap of the active layer, and the first semiconductor layer has a band gap which is narrower than a band gap of the second semiconductor layer.
Claim 9
Dependent Claim
32 words
A distributed feedback semiconductor laser according to claim 6, wherein the projections are each curved, and the thickness of the quantum well light absorption layer changes periodically and non-linearly along a cavity.
Claim 10
Dependent Claim
18 words
A distributed feedback semiconductor laser according to claim 6, wherein the active layer has a quantum well structure.
Claim 11
Dependent Claim
19 words
A distributed feedback semiconductor laser according to claim 6, wherein the active layer has a strained quantum well structure.
Claim 12
Dependent Claim
70 words
A distributed feedback semiconductor laser, comprising: an active layer for generating laser light; and a gain-coupled diffraction grating, wherein: the diffraction grating includes: a plurality of projections and grooves periodically arranged; and a quantum well light absorption layer including a plurality of parts respectively provided in the grooves, and the quantum well light absorption layer has a band gap which is narrower than a band gap of the active layer.
Claim 13
Dependent Claim
70 words
A distributed feedback semiconductor laser, comprising: an active layer for generating laser light; and a gain-coupled diffraction grating, wherein: the diffraction grating includes: a plurality of projections and grooves periodically arranged; and a quantum well light absorption layer including a plurality of parts respectively provided in the grooves, and the quantum well light absorption layer has a band gap which is narrower than a band gap of the active layer.
Claim 14
Dependent Claim
35 words
A distributed feedback semiconductor laser according to claim 10, wherein the projections and the grooves are located at a surface of an InP layer, and the quantum well light absorption layer is formed of InAsP.
Claim 15
Dependent Claim
38 words
A distributed feedback semiconductor laser according to claim 10, wherein each part of the quantum well light absorption layer has a size along the cavity which is no greater than 20% of one period of the diffraction grating.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-07-23 | 2000-01-22 | 2000-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-07-23 | 2004-01-22 | 2004-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-07-23 | 2008-01-22 | 2008-07-23 | $7700.00 | Window Closed / Lapsed |