US3675154A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dispersion compensation in lasers
Assignee: AT&T Inc
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Filing: 1970-10-01
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Granted: 1972-07-04
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Expires: 1990-10-01
Abstract
Abstract The normal dispersion of a solid state active laser medium is compensated for by means of an intracavity multireflection device such as a pair of spaced parallel diffraction gratings or a Gires-Tournois interferometer.
Inventors
- 👤 Michel Albert Duguay
- 👤 John Wilfred Hansen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:30
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/10; H01S3/11; H01S3/1106; H01S3/1112; H01S3/1115; H01S3/05; H01S3/08; H01S3/08004; H01S3/08009; H01S3/106; H01S3/1062
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
103 words
Laser apparatus including an optical cavity resonator, an active medium disposed within said resonator, means for pumping said medium to produce stimulated coherent radiation within a range of optical frequencies, means for coupling out of said resonator radiation in the form of optical pulses, said medium being disadvantageously characterized by the dispersive property that radiation at higher frequencies within said range undergoes different time delays than radiation at lower frequencies within said range, and characterized by multiple-reflection means disposed within said resonator for compensating said dispersive property so that radiation at substantially all frequencies within said range undergoes substantially the same time delay.
Claim 2
Dependent Claim
103 words
Laser apparatus including an optical cavity resonator, an active medium disposed within said resonator, means for pumping said medium to produce stimulated coherent radiation within a range of optical frequencies, means for coupling out of said resonator radiation in the form of optical pulses, said medium being disadvantageously characterized by the dispersive property that radiation at higher frequencies within said range undergoes different time delays than radiation at lower frequencies within said range, and characterized by multiple-reflection means disposed within said resonator for compensating said dispersive property so that radiation at substantially all frequencies within said range undergoes substantially the same time delay.
Claim 3
Dependent Claim
64 words
The laser apparatus of claim 1 wherein said active medium is characterized by positive dispersion whereby radiation at higher frequencies within said range undergoes longer time delays than radiation at lower frequencies within said range and said multiple-reflection means is characterized by negative dispersion whereby radiation at higher frequencies within said range undergoes shorter time delays than radiation at lower frequencies within said range.
Claim 4
Dependent Claim
17 words
The laser apparatus of claim 2 wherein said multiple reflection means comprises at least one Gires-Tournois interferometer.
Claim 5
Dependent Claim
58 words
The laser apparatus of claim 3 wherein said interferometer is characterized by a periodic time delay versus frequency characteristic including within each period substantially linear portions having both positive and negative slopes, said interferometer being adapted so that the center frequency of said laser radiation coincides with a substantially linear negative slope portion within one of said periods.
Claim 6
Dependent Claim
100 words
The laser apparatus of claim 4 wherein said interferometer comprises a first mirror of high reflectivity and a second mirror of intermediate reflectivity in spaced parallel relation with said first mirror, the power reflectivity of said second mirror being approximately 25 percent and wherein said interferometer is constructed to satisfy approximately the following relationship where g is the group delay per reflection of said radiation from said interferometer, Nu is the optical frequency of said laser radiation; e is the optical path length separating said mirrors and T (e ) is a tuning factor varied between about 0.5 and 1.0.
Claim 7
Dependent Claim
42 words
The laser apparatus of claim 3 including a second Gires-Tournois interferometer in spaced parallel relation with said one interferometer, said interferometers being obliquely disposed with respect to the axis of said resonator so that said radiation undergoes multiple reflections between said interferometers.
Claim 8
Dependent Claim
60 words
The laser apparatus of claim 2 wherein said multiple reflection means comprises a first diffraction grating disposed at an oblique angle with respect to the axis of said resonator, a second diffraction grating, substantially identical to said first diffraction grating, disposed in spaced parallel relation with said first diffraction grating so that said radiation undergoes multiple reflections between said gratings.
Claim 9
Dependent Claim
99 words
The laser apparatus of claim 7 wherein said diffraction gratings are constructed to satisfy approximately the following relationship where dg/d Nu is the group delay dispersion of sAid radiation in traversing said active medium in both the forward and backward directions, g is the group delay, Nu is the optical center frequency of said radiation, c is the speed of light in said medium, gamma is the angle of incidence of said radiation on one of said gratings, d is the ruling spacing of said gratings, and b is the distance along a radiation path measured between said gratings.
Claim 10
Dependent Claim
15 words
The laser apparatus of claim 8 wherein said angle of incidence is approximately 60* .
Claim 11
Dependent Claim
18 words
The laser apparatus of claim 2 wherein the longitudinal modes of said radiation within said resonator are phased-locked.
Claim 12
Dependent Claim
77 words
The laser apparatus according to claim 2 wherein said multiple reflection means overcompensates for said positive dispersion of said active medium, thereby to produce within said resonator a net negative dispersion in the pulsed radiation coupled out of said resonator so that radiation at higher frequencies undergoes less time delay than radiation at lower frequencies, and in combination with extra-cavity positive dispersion means disposed in the path of said coupled radiation for compensating the negative dispersion therein.
Claim 13
Dependent Claim
26 words
The laser apparatus of claim 11 wherein said positive dispersion means comprises a body of material substantially the same as the material of said active medium.
References Cited (Backward Citations)
US3551034A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-04 | 1976-01-03 | 1976-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-04 | 1980-01-03 | 1980-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-04 | 1984-01-03 | 1984-07-04 | $7700.00 | Window Closed / Lapsed |