US3715162A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Free exciton indirect transition laser
Assignee: 3M Co
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Filing: 1971-04-19
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Granted: 1973-02-06
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Expires: 1991-04-19
Abstract
Abstract A method and apparatus for selecting a direct band gap semiconductor crystal for use as a room temperature operable laser material. The crystal is selected when its emission spectrum is characterized by a series of peaks separated in energy by the energy of one longitudinal optical phonon and when the zero intensity extrapolation point on the low energy side of the highest energy peak of the series is below the lowest energy exciton peak of its reflection spectrum by an amount equal to the energy of one longitudinal optical phonon. The emission and reflection spectra are produced at 77*K.
Inventors
- 👤 W Tait
- 👤 R Weiher
- 👤 D Campbell
- 👤 J Packard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 11:37
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/09; H01S3/0955; H01S3/0959
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
176 words
A method of selecting a direct band gap semiconductor crystal for use as a room temperature operable laser material characterized by an emission spectrum which includes a series of emission line peaks which are separated by an energy difference which corresponds to one longitudinal optical phonon comprising: a. producing a reflection spectrum of a said crystal at a predetermined cryogenic temperature to obtain the exciton peaks characteristic of said crystal; b. producing a spontaneous emission spectrum of said crystal at said predetermined cryogenic temperature, c. extrapolating a straight line function from the low energy side of the highest produced energy peak of said series of emission line peaks to obtain a zero intensity point for said highest peak, d. comparing said reflection spectrum and said spontaneous emission spectrum, including said extrapolated zero intensity point, and e. selecting for use as room temperature operable laser material those semiconductor crystals whose extrapolated zero intensity point is below the lowest energy exciton peak of said reflection spectrum by an amount equal to the energy of one longitudinal optical phonon.
Claim 2
Independent Claim
176 words
A method of selecting a direct band gap semiconductor crystal for use as a room temperature operable laser material characterized by an emission spectrum which includes a series of emission line peaks which are separated by an energy difference which corresponds to one longitudinal optical phonon comprising: a. producing a reflection spectrum of a said crystal at a predetermined cryogenic temperature to obtain the exciton peaks characteristic of said crystal; b. producing a spontaneous emission spectrum of said crystal at said predetermined cryogenic temperature, c. extrapolating a straight line function from the low energy side of the highest produced energy peak of said series of emission line peaks to obtain a zero intensity point for said highest peak, d. comparing said reflection spectrum and said spontaneous emission spectrum, including said extrapolated zero intensity point, and e. selecting for use as room temperature operable laser material those semiconductor crystals whose extrapolated zero intensity point is below the lowest energy exciton peak of said reflection spectrum by an amount equal to the energy of one longitudinal optical phonon.
Claim 3
Dependent Claim
15 words
A method according to claim 1 wherein said predetermined cryogenic temperature is about 77* K.
Claim 4
Dependent Claim
66 words
A method according to claim 1 wherein the steps of producing said emission spectrum comprises measuring the spontaneous emission spectrum of said crystal by exciting a face of said crystal with electrons having a predetermined energy to excite said crystal into at least a region of spontaneous emission, and by selecting for measurement such emission as has not been subjected to appreciable absorption within said crystal.
Claim 5
Dependent Claim
26 words
A method according to claim 3 wherein the step of producing said emission spectrum further comprises measuring emission emitted in a direction parallel to said face.
References Cited (Backward Citations)
US3393373A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |