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US5276702A
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Gain-coupled distributed-feedback semiconductor laser
Assignee: Avago Technologies International Sales Pte Ltd
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Filing: 1992-05-13
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Granted: 1994-01-04
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Expires: 2012-05-13
Abstract
Abstract In a distributed feedback semiconductor laser, the active medium has a periodic thickness variation in the light propagation direction so as to generate a periodic gain variation, while maintaining the effective refractive index constant, and has a discrete multi-quantum wire structure.
Inventors
- 👤 Marina Meliga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:45
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/30; H01S5/34; B; B82; B82Y; B82Y20/00; H01S5/10; H01S5/12; H01S5/1228; H01S5/341
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
101 words
In a gain-coupled distributed-feedback laser, wherein optical feedback is obtained by means of a grating of passive semiconductor material extending an entire length of the laser length in a light propagation direction, and wherein an active medium has a periodically changing thickness so as to introduce a periodic gain variation, the improvement wherein the active medium is present only in grooves of the grating and comprises discrete layers alternating with layers of a semiconductor material of different band gap, which layers form in each groove respectively wires and barriers of a multi-quantum wire structure, oriented perpendicular to the light propagation direction.
Claim 2
Dependent Claim
101 words
In a gain-coupled distributed-feedback laser, wherein optical feedback is obtained by means of a grating of passive semiconductor material extending an entire length of the laser length in a light propagation direction, and wherein an active medium has a periodically changing thickness so as to introduce a periodic gain variation, the improvement wherein the active medium is present only in grooves of the grating and comprises discrete layers alternating with layers of a semiconductor material of different band gap, which layers form in each groove respectively wires and barriers of a multi-quantum wire structure, oriented perpendicular to the light propagation direction.
Claim 3
Dependent Claim
21 words
The improvement defined in claim 1 wherein an optical confinement layer is provided on the grating and the multi-quantum wire structure.
Claim 4
Dependent Claim
86 words
The improvement defined in claim 1 wherein the grating is made of a material whose refractive index is such that the effective refractive index, outside the grooves, satisfies a condition ##EQU3## where Nw and Nb are the number of wires and of barriers respectively; tw and tb are the thicknesses of the wires and the barriers respectively; nw and nb are the refractive indices of the wires and the barriers respectively, so as to ensure constancy of an effective refractive index in the light propagation direction.
Claim 5
Independent Claim
120 words
A method of fabricating a gain-coupled distributed-feedback laser, wherein optical feedback is obtained by means of a grating of passive semiconductor material extending an entire length of the laser length in a light propagation direction, and wherein an active medium has a periodically changing thickness so as to introduce a periodic gain variation, in which on a layer of a first passive semiconductor material the grating of a second passive material is forms, said method comprising the steps of growing a plurality of layers of active material separated by layers of a further passive material with a wider band gap in each groove of the grating, so as to form a quantum wire structure orthogonal to the light propagation direction.
Claim 6
Independent Claim
120 words
A method of fabricating a gain-coupled distributed-feedback laser, wherein optical feedback is obtained by means of a grating of passive semiconductor material extending an entire length of the laser length in a light propagation direction, and wherein an active medium has a periodically changing thickness so as to introduce a periodic gain variation, in which on a layer of a first passive semiconductor material the grating of a second passive material is forms, said method comprising the steps of growing a plurality of layers of active material separated by layers of a further passive material with a wider band gap in each groove of the grating, so as to form a quantum wire structure orthogonal to the light propagation direction.
Claim 7
Dependent Claim
26 words
The method defined in claim 4 wherein said grooves have a nonzero width in correspondence at their vertices, to avoid active material growth on groove walls.
Claim 8
Dependent Claim
52 words
The method defined in claim 4 wherein while growing the quantum wire structures, surface portions of the grating between adjacent grooves are kept covered with a photoresist layer interacting with the quantum wire material to confer to it a structure allowing an easy removal of such material possibly grown outside the grooves.
Claim 9
Dependent Claim
20 words
The method defined in claim 4 wherein an optical confinement layer is deposited on the grating and quantum wire structures.
References Cited (Backward Citations)
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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) | 1997-01-03 | 1997-07-05 | 1998-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-01-03 | 2001-07-05 | 2002-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-01-03 | 2005-07-05 | 2006-01-04 | $7700.00 | Window Closed / Lapsed |