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US3789235A
Expired / Lapsed
US
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Far infrared coherent radiation source employing charge carrier spin nonlinearity in a magnetic field
Assignee: AT&T Inc
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Filing: 1972-09-28
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Granted: 1974-01-29
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Expires: 1992-09-28
Abstract
Abstract There are disclosed far infrared coherent radiation sources in which a sample of material capable of spin-flip transitions is subjected to an adjustable magnetic field and pumped by at least one coherent light beam. Some of the sources generate both tunable spin-flip laser radiation and far infrared radiation at the tunable spin-flip (or spin resonance) frequency. Others of the sources provide mixing of two input coherent radiations of adjustable frequency to produce phase-matched far infrared coherent radiation at the difference frequency which substantially coincides with the spin-flip frequency. In all of these sources only one crystal of the material is typically subjected to the magnetic field. A particular advantage of these sources is the possibility of tuning the far infrared output over a wide frequency range. An important aspect of the invention is that phase-matching greatly enhances the far infrared output.
Inventors
- 👤 T Bridges
- 👤 V Nguyen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:16
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/30
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
102 words
A far infrareD coherent radiation source comprising a sample of a semiconductive material transmissive in both a first frequency range above about 30,000 GHz and in a second frequency range between about 300 GHz and 30,000 GHz, means for applying a magnetic field to said sample to provide a spin-flip frequency in said second frequency range and means for pumping said sample with at least a first coherent beam of radiation in said first frequency range, said sample and said pumping means being mutually oriented for phase-matched generation of at least a coherent radiation at the spin-flip frequency in a threefrequency interaction.
Claim 2
Dependent Claim
102 words
A far infrareD coherent radiation source comprising a sample of a semiconductive material transmissive in both a first frequency range above about 30,000 GHz and in a second frequency range between about 300 GHz and 30,000 GHz, means for applying a magnetic field to said sample to provide a spin-flip frequency in said second frequency range and means for pumping said sample with at least a first coherent beam of radiation in said first frequency range, said sample and said pumping means being mutually oriented for phase-matched generation of at least a coherent radiation at the spin-flip frequency in a threefrequency interaction.
Claim 3
Dependent Claim
46 words
A far infrared coherent radiation source according to claim 1 in which the pumping means comprises sources of first and second coherent beams in the first frequency range, said sources supplying beams having a frequency difference equal to the spin-flip frequency and having mutually orthogonal polarizations.
Claim 4
Dependent Claim
40 words
A far infrared coherent radiation source according to claim 2 in which the first and seocnd pumping sources are lasers operating near the bandgap of the sample or semiconductive material to provide the phase-matching by anomalous dispersion in the sample.
Claim 5
Dependent Claim
80 words
A far infrared coherent radiation source according to claim 2, in which the magnetic field applying means includes means for varying the magnetic field, said source including means for varying the temperature of the sample to facilitate phase-matching of the radiations therein and means external to said sample for resonating the far infrared radiation generated therein at the spin-flip frequency, including means for tuning said external resonating means in frequency to track the spin-flip frequency as the magnetic field varies.
Claim 6
Dependent Claim
103 words
A far infrared coherent radiation source comprising a sample of a semiconductive material transmissive in both a first frequency range above about 30,000 GHz and in a second frequency range between about 300 GHz and 30,000 GHz, means for applying a magnetic field to said sample to provde a spin-flip frequency in said second frequency range, means for pumping said sample with a coherent beam of radiation in said first frequency range to drive both laser action at a frequency that is Raman shifted from the pump frequency by the spin-reversal frequency and to drive a second coherent radiation at said spin-flip frequency.
Claim 7
Dependent Claim
103 words
A far infrared coherent radiation source comprising a sample of a semiconductive material transmissive in both a first frequency range above about 30,000 GHz and in a second frequency range between about 300 GHz and 30,000 GHz, means for applying a magnetic field to said sample to provde a spin-flip frequency in said second frequency range, means for pumping said sample with a coherent beam of radiation in said first frequency range to drive both laser action at a frequency that is Raman shifted from the pump frequency by the spin-reversal frequency and to drive a second coherent radiation at said spin-flip frequency.
Claim 8
Dependent Claim
136 words
A far infrared coherent radiation source comprising a sample of a semiconductive material transmissive in both a first frequency range about 30,000 GHz and in a second frequency range between about 300 GHz and 30,000 GHz, means for applying a magnetic field to said sample to provide a spin-flip frequency in said second frequency range, and means for pumping said sample with a coherent beam in said first frequency range, said sample and said pumping means being mutually adapted for generation of a first coherent radiation at said spin-flip frequency and a second coherent radiation at a frequency equal to the difference of the pump freqnuency and spin-reversal frequency, the beam of said pumping means having a selected frequency offset from the bandgap frequency of said sample to phase-match both generated radiations to said pumping beam.
Claim 9
Dependent Claim
136 words
A far infrared coherent radiation source comprising a sample of a semiconductive material transmissive in both a first frequency range about 30,000 GHz and in a second frequency range between about 300 GHz and 30,000 GHz, means for applying a magnetic field to said sample to provide a spin-flip frequency in said second frequency range, and means for pumping said sample with a coherent beam in said first frequency range, said sample and said pumping means being mutually adapted for generation of a first coherent radiation at said spin-flip frequency and a second coherent radiation at a frequency equal to the difference of the pump freqnuency and spin-reversal frequency, the beam of said pumping means having a selected frequency offset from the bandgap frequency of said sample to phase-match both generated radiations to said pumping beam.
Claim 10
Dependent Claim
29 words
A far infrared coherent radiation source according to claim 6 in which the pumping means provides a coherent pumping beam polarized parallel to the direction of the magnetic field.
Claim 11
Dependent Claim
20 words
A far infrared coherent radiation source according to claim 6 including means for providing a selected temperature of the sample.
Claim 12
Dependent Claim
30 words
A far infrared coherent radiation source according to claim 6, inlcuding a grating structure for phase-matching the pumping coherent beam with the Raman shifted radiation and the far infrared radiation.
Claim 13
Dependent Claim
59 words
A far infrared coherent radiation source according to claim 5 including means for increasing the density of charge carriers in a first region of said sample, traversed by the beam of the pumping means before a Second region of said sample, said second region of said sample having a charge carrier density less than that in the first region.
Claim 14
Dependent Claim
49 words
A far infrared coherent radiation source according to claim 10 in which the means for increasing the charge carrier density in the first region comprises means for creating an essentially static electric field across said first region with a gradient sufficient to produce impact ionization in said first region.
Claim 15
Dependent Claim
50 words
A far infrared coherent radiation source according to claim 10 in which the means for increasing the charge carrier density in the first region comprises an external optical source and means for directing radiation from said source into said first region to produce substantial numbers of additional charge carriers therein.
Claim 16
Dependent Claim
39 words
A far infrared coherent radiation source accordint to claim 1 in which the sample has a particular impurity concentration that modifies the free carrier concentration to facilitate the phase-matching, the impurity concentration making a significant contribution to refractive index.
Claim 17
Dependent Claim
67 words
A far infrared coherent radiation source according to claim 10 in which the means for increasing the charge carrier density in the first region comprises a first means for supplying a first essentially static electric field across said first region, said source including a secnd means for supplying a seocnd essentially static electric field across said second region, said second field being less then said first field.
Claim 18
Dependent Claim
38 words
A far infrared coherent radiation source according to claim 5 including means encompassing the sample for resonating the far infrared radiation, said sample having two regions of differing carrier concentrations, said two regions having differing dopant impurity concentrations.
Claim 19
Dependent Claim
36 words
A far infrared coherent radiation source according to claim 6 in which the pumping means provides the coherent pumping beam with an adjustable frequency to facilitate the phase-matching of both generated radiations to the pumping beam.
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) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |