US3922618A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiple transition laser
Assignee: Massachusetts Institute of Technology
•
Filing: 1974-05-28
•
Granted: 1975-11-25
•
Expires: 1994-05-28
Abstract
Abstract A laser is forced to oscillate stably and simultaneously upon multiple transitions by modulation of emissions in the laser cavity at a frequency related to the frequency spacing D between the desired transitions. Spread of lasing action to further transitions in the series is achieved by pressure line-broadening and/or additional modulation related to step frequency d by which spacing D may approximately vary through the series. By selection of the modulation frequencies Dm and dm as integer multiples of the cavity resonance, cavity regeneration is assured at the various transitions leading to simultaneous oscillation at many frequencies. In the embodiment shown, a CO2 molecular laser, the pulses are of subnanosecond duration, less than the crossrelaxation time between the various rotational states of the molecular band. An amplifier receiving the output of such laser oscillator gives up its energy at the various transitions even when pumped with the very short pulse lengths. A CO2 laser oscillator and amplifier chain constructed to operate in the atmospheric and super atmospheric regime is shown, its subnanosecond pulses having extremely high energy, useful in controlled thermonuclear and lidar applications. Also by use of pressure line-broadening to operate the laser upon many frequencies spaced equally apart, but each arising from a different transition, a uniform repetition rate of very short pulses is achievable by interference of the various laser lines.
Inventors
- 👤 Ali Javan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:11
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/09; H01S3/097; H01S3/0971; H01S3/09713; H01S3/09716; H01S3/10; H01S3/106; H01S3/107
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
125 words
A laser comprising an active laser medium disposed within a resonant cavity, the laser medium capable of supporting laser oscillations at different frequencies corresponding to transitions between different upper and different lower energy states, the peak frequencies of the gain curves for selected first and second transitions being spaced apart a predetermined characteristic amount D1,2, in the microwave range, of value dependent upon the nature of the laser medium, an optical modulator disposed within said laser cavity and a modulating source for driving said modulator to modulate radiation in said cavity at frequency Dm corresponding substantially to D1,2 to establish through generation of a side band, stable laser oscillations at first and second frequencies corresponding to the gain curves of said first and second transitions.
Claim 2
Dependent Claim
125 words
A laser comprising an active laser medium disposed within a resonant cavity, the laser medium capable of supporting laser oscillations at different frequencies corresponding to transitions between different upper and different lower energy states, the peak frequencies of the gain curves for selected first and second transitions being spaced apart a predetermined characteristic amount D1,2, in the microwave range, of value dependent upon the nature of the laser medium, an optical modulator disposed within said laser cavity and a modulating source for driving said modulator to modulate radiation in said cavity at frequency Dm corresponding substantially to D1,2 to establish through generation of a side band, stable laser oscillations at first and second frequencies corresponding to the gain curves of said first and second transitions.
Claim 3
Dependent Claim
18 words
The laser of claim 1 wherein said different energy states are due to molecules in different rotational states.
Claim 4
Dependent Claim
17 words
The laser of claim 1 wherein said laser medium includes carbon dioxide, Dm being about 54,000 MHz.
Claim 5
Dependent Claim
45 words
The laser of claim 1 wherein said cavity has a characteristic resonance c/2L where c is the speed of light and L is the characteristic mode determining length of the laser cavity, and said modulation frequency is an integer multiple n of said cavity resonance,
Claim 6
Dependent Claim
78 words
The laser of claim 1 wherein the peak of the gain curve of a third transition of said laser medium is spaced from the peak of said second transition a predetermined characteristic amount D2, 3, different from but of generally the same value as the spacing D1,2 between the peaks of said first and second transitions, and means employing said modulation for establishing laser oscillation at a third frequency corresponding to the gain curve of said third transition.
Claim 7
Dependent Claim
55 words
The laser of claim 5 including means for maintaining the pressure of said laser medium at a selected value to produce line-broadening sufficient that a side band, generated in conjunction with establishing said laser oscillations at said first and second transitions, lies within the gain curve of said third transition and establishes stable oscillations thereat.
Claim 8
Dependent Claim
71 words
The laser of claim 5 wherein the difference, d, between said spacings, d D1,2 - D2,3, lies in the range comprising the microwave and radio frequency ranges, and a modulating source driving a modulator to modulate radiation in said cavity at frequency dm corresponding substantially to d to establish, through generation of a side band, stable laser oscillations at a third frequency corresponding to the gain curve of said third transition.
Claim 9
Dependent Claim
17 words
The laser of claim 7 wherein said laser medium includes carbon dioxide, dm being about 740 MHz.
Claim 10
Dependent Claim
32 words
The laser of claim 7 wherein dm n1 c/2L where c is the speed of light, L is the characteristic mode determining length of the laser cavity, and n1 is an integer.
Claim 11
Dependent Claim
23 words
The laser of claim 7 wherein a single electro-optic modulator is arranged to be driven at both said Dm and dm modulation frequencies.
Claim 12
Dependent Claim
23 words
The laser of claim 10 wherein said modulator comprises an optically active medium whose refractive index changes in response to said modulating sources.
Claim 13
Dependent Claim
15 words
The laser of claim 10 wherein said dm modulating source modulates said Dm modulating source.
Claim 14
Dependent Claim
39 words
The laser of claim 7 wherein side bands generated through interaction of said modulations at frequencies Dm and dm correspond to and produce stable oscillations at a more remote frequency corresponding to the gain curve of a Further transition.
Claim 15
Dependent Claim
56 words
The laser of claim 7 including means for maintaining the pressure of said laser medium at a selected value to produce line-broadening sufficient that a side band, generated in conjunction with establishing said laser oscillations at said first, second, and third frequencies, lies within the gain curve of a more remote transition and establishes oscillations thereat.
Claim 16
Dependent Claim
36 words
The laser of claim 1 wherein said different energy states are due to molecules in different rotational states, said laser constructed to emit pulses of duration shorter than the time of cross-relaxation between said energy states.
Claim 17
Dependent Claim
30 words
The laser of claim 1 in combination with a laser amplifier receiving the output of said laser and having an output exhibiting amplification of both said first and second frequencies.
Claim 18
Dependent Claim
61 words
The laser of claim 1 wherein said different energy states are due to molecules in different rotational states, said laser constructed to emit pulses of duration shorter than the time of cross-relaxation between said energy states in combination with a laser amplifier receiving the output of said laser and having an output exhibiting amplification of both said first and second frequencies.
Claim 19
Dependent Claim
21 words
The laser of claim 1 in the form of a CO2 laser with the laser medium at least at atmospheric pressure.
Claim 20
Dependent Claim
185 words
A laser construction capable of emitting ultrashort pulses comprising an active laser medium disposed within a resonant cavity, the laser medium capable of supporting laser oscillations at a series of different frequencies corresponding to transitions between different upper and different lower energy states attributable to molecules in different rotational states, adjacent transitions in said series being spaced apart by microwave frequencies D of the order of 10,000 MHz or more, means for maintaining the pressure of said laser medium at a selected value to produce line-broadening of the gain curves of said transitions such that each of a series of N frequencies spaced successively apart by a given microwave frequency Dm of value of the order of D falls within the gain curve of a corresponding different transition, an optical modulator disposed within said laser cavity and a modulating source driving said modulator to modulate radiation in said cavity at said frequency Dm to establish through generation of side bands radiation at N different transitions, constructive interference between the resulting radiation at said N transitions producing a series of pulses of pulse width t 1/NDm.
Claim 21
Dependent Claim
185 words
A laser construction capable of emitting ultrashort pulses comprising an active laser medium disposed within a resonant cavity, the laser medium capable of supporting laser oscillations at a series of different frequencies corresponding to transitions between different upper and different lower energy states attributable to molecules in different rotational states, adjacent transitions in said series being spaced apart by microwave frequencies D of the order of 10,000 MHz or more, means for maintaining the pressure of said laser medium at a selected value to produce line-broadening of the gain curves of said transitions such that each of a series of N frequencies spaced successively apart by a given microwave frequency Dm of value of the order of D falls within the gain curve of a corresponding different transition, an optical modulator disposed within said laser cavity and a modulating source driving said modulator to modulate radiation in said cavity at said frequency Dm to establish through generation of side bands radiation at N different transitions, constructive interference between the resulting radiation at said N transitions producing a series of pulses of pulse width t 1/NDm.
Claim 22
Dependent Claim
25 words
The laser construction of claim 19 wherein said laser medium is CO2, Dm being greater than 30,000 MHz, and N being about 10 or more.
Claim 23
Dependent Claim
26 words
The laser construction of claim 19 wherein the repetition rate of pulses emitted from said laser is steady at a frequency Dm controlled by said modulation.
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) | 1978-11-24 | 1979-05-26 | 1979-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-24 | 1983-05-26 | 1983-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-24 | 1987-05-26 | 1987-11-25 | $7700.00 | Window Closed / Lapsed |