US3654497A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semiconductor lasers utilizing internal saturable absorbers
Assignee: AT&T Inc
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Filing: 1969-12-01
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Granted: 1972-04-04
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Expires: 1989-12-01
Abstract
Abstract Trapping centers are controllably introduced into a junction laser by diffusing a P region to within at least 1.5 Mu of the junction. The centers, which act as saturable absorbers, produce bistable regions of operation in c.w. junction lasers operating above the delay transition temperature, the laser being either on or off depending on its previous history of operation. Optical logic and memory devices, as well as methods for fabrication, are discussed.
Inventors
- 👤 John C Dyment
- 👤 Thomas L Paoli
- 👤 Jose E Ripper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:12
CPC Classifications
G; G02; G02F; G02F3/00; G02F3/02; G02F3/026; H; H01; H01S; H01S5/00; H01S5/06; H01S5/0601
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
78 words
An optical device comprising: a continuous wave P-N junction laser having a characteristic delay transition temperature, means for maintaining the temperature of said junction above said delay transition temperature, and means for creating near to said junction optical trapping centers capable of undergoing saturable absorption in response to an optical field near the junction, said creating means comprising a P region located on the P-side of said junction and separated therefrom by a distance less than 1.5 microns.
Claim 2
Dependent Claim
78 words
An optical device comprising: a continuous wave P-N junction laser having a characteristic delay transition temperature, means for maintaining the temperature of said junction above said delay transition temperature, and means for creating near to said junction optical trapping centers capable of undergoing saturable absorption in response to an optical field near the junction, said creating means comprising a P region located on the P-side of said junction and separated therefrom by a distance less than 1.5 microns.
Claim 3
Dependent Claim
13 words
The device of claim 1 wherein said laser is a gallium arsenide laser.
Claim 4
Dependent Claim
26 words
The device of claim 2 wherein the depth of said junction is about 1.8 microns and the depth of said P region is about 1.0 microns.
Claim 5
Dependent Claim
40 words
The device of claim 1 in combination with means for switching said device from one stable state to another comprising means for varying the injection current applied to said laser so as to alternately saturate and unsaturate said trapping centers.
Claim 6
Dependent Claim
66 words
The device of claim 4 wherein said means for creating optical trapping centers near to the junction of said laser comprises a P region located within the P-side of said laser and near to only a portion of said junction, said current varying means being sufficient to cause said p region to undergo saturable absorption and the remaining portion of said P-side to undergo gain saturation.
Claim 7
Dependent Claim
73 words
The device of claim 1 for use as a unitary optical logic device including said C.W. laser having a longitudinal cavity axis along which radiation is emitted, second and third independent junction lasers disposed transverse to the longitudinal axis of said c.w. laser, said trapping centers being located near to at least a portion of the junction of said C.W. laser, said portion being common to at least one of said independent lasers.
Claim 8
Dependent Claim
45 words
The device of claim 6 wherein the external radiation from said one independent laser adjacent to said common portion causes said centers within said portion to saturate, the external radiation of said other independent laser causing gain saturation in said remaining portion of said laser.
Claim 9
Dependent Claim
45 words
The device of claim 7 for use as a nondestructive memory wherein the injection current applied to said adjacent laser is adapted so that it lases only if said laser lases and said other independent laser lases only when said C.W. laser does not lase.
Claim 10
Dependent Claim
97 words
The device of claim 7 wherein saturation of said centers lowers the current threshold Ith of said C.W. laser by an amount Delta IE and gain saturation increases by Delta IF, the injection current I of said C.W. laser being maintained such that (Ith - Delta IE) < I and I is less than the smaller of Ith and (Ith - Delta IE + Delta IF), thus performing the logic function D E+F, where D, E and F refer, respectively, to the logic states of said C.W. laser, said one independent laser and said other independent laser.
Claim 11
Dependent Claim
97 words
The device of claim 7 wherein saturation of said center lowers the current threshold Ith of said C.W. laser by an amount Delta IE and gain saturation increases it by Delta IF, the injection current I of said C.W. laser being maintained such that I < (Ith + Delta IF) and greater than the larger of Ith and (Ith - Delta IE + Delta IF), thus performing the logic function D E .F, where D, E and F refer, respectively, to the logic states of said C.W. laser, said one independent laser and said other independent laser.
Claim 12
Dependent Claim
69 words
The device of claim 6 wherein said trapping centers are located adjacent to the entire P-N junction of said C.W. laser and wherein the external radiation from one of said independent lasers lowers the current threshold Ith of said C.W. laser by an amount Delta I whereas the external radiation from both of said independent lasers operating simultaneously lowers said threshold by an amount of about 2 Delta I.
Claim 13
Dependent Claim
31 words
The device of claim 11 for use as an optical OR gate comprising means for applying to said C.W. laser injection current of magnitude between (Ith - Delta I and Ith.
Claim 14
Dependent Claim
36 words
The device of claim 11 for use as an optical AND gate comprising means for applying to said C.W. laser an injection current of magnitude between (Ith - 2 Delta I) and (Ith - Delta I).
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-04-04 | 1975-10-04 | 1976-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-04 | 1979-10-04 | 1980-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-04 | 1983-10-04 | 1984-04-04 | $7700.00 | Window Closed / Lapsed |