US4740987A
Expired / Lapsed
US
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Distributed-feedback laser having enhanced mode selectivity
Assignee: Nokia Bell Labs
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Filing: 1986-06-30
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Granted: 1988-04-26
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Expires: 2006-06-30
Abstract
Abstract A distributed-feedback laser includes in its grating a localized phase-slip discontinuity which is placed off-center. Such discontinuity results in a quarter-wave phase slip, and it can be placed, e.g., such as to maximize the difference between threshold gain of the lowest-lasing mode and cavity loss of the next-to-lowest-lasing mode. The invention is applicable especially where laser output intensity differs at two output facets and results in enhanced mode selectivity during laser operation.
Inventors
- 👤 Samuel L. McCall, Jr.
- 👤 Philip M. Platzman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:27
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/10; H01S5/12; H01S5/124
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
109 words
Device for stimulated emission of optical radiation, said device comprising an active layer, means for creating a population inversion in said active layer, and distributed feedback means having two endpoints and adapted to be in optical coupling relationship with radiation propagating along said active layer in two mutually opposite directions, said distributed feedback means providing, in said directions, for spatially periodic variations of effective refractive index and a spatially localized phase-slip discontinuity, said device being CHARACTERIZED IN THAT said localized phase-slip discontinuity is spaced from an endpoint of said distributed feedback means by a distance which is not more than 0.45 times the length of said distributed feedback means.
Claim 2
Dependent Claim
109 words
Device for stimulated emission of optical radiation, said device comprising an active layer, means for creating a population inversion in said active layer, and distributed feedback means having two endpoints and adapted to be in optical coupling relationship with radiation propagating along said active layer in two mutually opposite directions, said distributed feedback means providing, in said directions, for spatially periodic variations of effective refractive index and a spatially localized phase-slip discontinuity, said device being CHARACTERIZED IN THAT said localized phase-slip discontinuity is spaced from an endpoint of said distributed feedback means by a distance which is not more than 0.45 times the length of said distributed feedback means.
Claim 3
Dependent Claim
19 words
Device of claim 1 in which, aside from said discontinuity, said effective refractive index variations are uniformly spatially periodic.
Claim 4
Dependent Claim
20 words
Device of claim 1 in which said localized phase-slip discontinuity is such as to result in a quarter-wave phase slip.
Claim 5
Dependent Claim
34 words
Device of claim 1 in which said localized phase-slip discontinuity is placed so as to maximize the difference between threshold gain of the lowest-lasing mode and the cavity loss of the next-to-lowest lasing mode.
Claim 6
Dependent Claim
38 words
Device of claim 1 in which said localized phase-slip discontinuity extends over a region of said distributed feedback means, said region having a length which does not exceed 20 percent of the length of said distributed feedback means.
Claim 7
Dependent Claim
26 words
Device of claim 5 in which effective refractive index in said region differs from effective refractive index in the complementary portion of said distributed feedback means.
Claim 8
Dependent Claim
15 words
Device of claim 1 in which said spatial variations result from corrugations at an interface.
Claim 9
Dependent Claim
12 words
Device of claim 7 in which said corrugations are produced by etching.
Claim 10
Dependent Claim
13 words
Device of claim 1 in which said spatial variations result from material variations.
Claim 11
Dependent Claim
12 words
Device of claim 9 in which said material variations comprise compositional variations.
Claim 12
Dependent Claim
12 words
Device of claim 9 in which said material variations comprise thickness variations.
Claim 13
Dependent Claim
14 words
Device of claim 1, said device having a cleaved facet as a reflecting surface.
Claim 14
Dependent Claim
14 words
Device of claim 1, said device having a saw-cut facet as a nonreflecting surface.
Claim 15
Dependent Claim
29 words
Device of claim 1 in which reflectivity at said two endpoints differs and in which said phase-slip discontinuity is situated nearer to the endpoint at which reflectivity is higher.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-04-26 | 1991-10-26 | 1992-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-04-26 | 1995-10-26 | 1996-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-04-26 | 1999-10-26 | 2000-04-26 | $7700.00 | Window Closed / Lapsed |