US3679994A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Broadband optically pumped semiconductive lasers
Assignee: AT&T Inc
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Filing: 1971-05-20
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Granted: 1972-07-25
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Expires: 1991-05-20
Abstract
Abstract The disclosed optically pumped masers and lasers employ multiple valley semiconductive devices for amplification and oscillation in the millimeter or submillimeter frequency range. This operation results from the population inversion of carriers within continuum states of the conduction band. Electronic charge carriers are excited to the conduction band from impurity levels of from the valence band by one-photon or two-photon optical pumping. The energy of excited carriers is selected to be just below the intervalley energy gap. A small electric field is able to create a transfer of charge carriers between the two valleys in order to obtain the carrier population peak near the intervalley energy level. The combination of the optical pumping and the appropriate small electric field avoids Gunn instabilities. A moderate magnetic field increases available gain at the expense of oscillation bandwidth by providing discrete energy levels below the intervalley energy gap.
Inventors
- 👤 Tran Van Nguyen
- 👤 Jagdeep Chandravadan Shah
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:50
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/30
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
90 words
A laser of the type comprising a body of a multiple valley semiconductive material and means for producing the stimulated emission of coherent radiation from a radiative transition not crossing the forbidden band, characterized in that said producing means comprises means for optically pumping said body to generate excited carriers in a band including said transition, and means for applying an electric field to said body to invert the populations of the levels of said transition, said field having a strength outside the range in which Gunn-effect instabilities are possible.
Claim 2
Dependent Claim
90 words
A laser of the type comprising a body of a multiple valley semiconductive material and means for producing the stimulated emission of coherent radiation from a radiative transition not crossing the forbidden band, characterized in that said producing means comprises means for optically pumping said body to generate excited carriers in a band including said transition, and means for applying an electric field to said body to invert the populations of the levels of said transition, said field having a strength outside the range in which Gunn-effect instabilities are possible.
Claim 3
Dependent Claim
63 words
A laser of the type claimed in claim 1 in which the multiple valley semiconductive material is a direct gap material selected to have the indiRect gap valley separated from the direct gap valley by an energy difference that is less than any energy of any absorptive transition is said material, said radiative transition having a photon energy less than said energy difference.
Claim 4
Dependent Claim
36 words
A laser of the type claimed in claim 1 in which the means for optically pumping said body includes a source providing transfer of charge carriers across the forbidden band by two-photon absorption in said body.
Claim 5
Dependent Claim
57 words
A laser of the type claimed in claim 1 in which the multiple valley semiconductive material has a selected impurity level within the forbidden band and in which the means for optically pumping said body includes a source providing transfer of charge carriers from said impurity level to the band including said radiative transition in said body.
Claim 6
Dependent Claim
40 words
A laser according to claim 1 in which the body of semiconductive material is a mixed crystal of two III-V semiconductive compounds, the mixture ratio being selected to determine the energy difference of the direct gap and indirect gap valleys.
Claim 7
Dependent Claim
35 words
A laser according to claim 5 in which the body of semiconductive material is a mixed crystal selected from the group of mixed crystals consisting of A1yGa1 yAs, GaAs1 yPy, A1yIn1 yAs, and A1yIn1 yP.
Claim 8
Dependent Claim
43 words
A laser according to claim 1 including means for applying a magnetic field to said body to produce a well-defined upper level for said radiative transition, said modified level having an energy width that increases available gain at the expense of oscillation bandwidth.
Claim 9
Dependent Claim
56 words
A laser according to claim 1 in which the body of semiconductive material is a mixed semiconductive crystal selected to have an indirect gap valley separated from the direct gap valley by an energy difference smaller than 4 kT, where k is Boltmann''s constant and T is the absolute temperature of said body in compatible units.
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) | 1975-07-25 | 1976-01-24 | 1976-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-25 | 1980-01-24 | 1980-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-25 | 1984-01-24 | 1984-07-25 | $7700.00 | Window Closed / Lapsed |