US3713042A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stabilized mode-locked laser arrangement
Assignee: AT&T Inc
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Filing: 1971-05-27
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Granted: 1973-01-23
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Expires: 1991-05-27
Abstract
Abstract A dither technique is embodied in an auxiliary feedback loop of a mode-locked laser which includes a main feedback loop. An error-control signal is generated in the auxiliary loop in response to the occurrence in the laser system of various types of perturbations such as, for example, cavity length changes. This error signal is applied to the main loop to restore the operating point of the laser to the midpoint of the range in which mode-locked operation occurs. In this way the laser is positively controlled to exhibit a stable mode-locked behavior over a long period of time despite the occurrence of perturbations that might otherwise cause the operating point of the laser to extend outside the mode-locked range.
Inventors
- 👤 T Kinsel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 01:33
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/10; H01S3/11; H01S3/1106; H01S3/1109; H01S3/13; H01S3/136
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
136 words
In combination, a multi-axial-mode laser comprising a cavity, and a modulator positioned within said cavity; a main feedback loop comprising means for extracting a signal from said laser cavity at the frequency that corresponds to the average axial-mode spacing of the laser, and means for processing said first-mentioned signal to drive said modulator in the phase-locked region of operation of said laser to achieve mode-locked operation, said main feedback loop also including a signal-controlled variable element; and an auxiliary feedback loop comprising means for extracting a signal from said laser cavity at a frequency that is low relative to the frequency of said firstmentioned signal, means for applying said second-mentioned signal to said variable element, and generating means for applying signals at said secondmentioned frequency to said means for processing and to said means for applying.
Claim 2
Dependent Claim
136 words
In combination, a multi-axial-mode laser comprising a cavity, and a modulator positioned within said cavity; a main feedback loop comprising means for extracting a signal from said laser cavity at the frequency that corresponds to the average axial-mode spacing of the laser, and means for processing said first-mentioned signal to drive said modulator in the phase-locked region of operation of said laser to achieve mode-locked operation, said main feedback loop also including a signal-controlled variable element; and an auxiliary feedback loop comprising means for extracting a signal from said laser cavity at a frequency that is low relative to the frequency of said firstmentioned signal, means for applying said second-mentioned signal to said variable element, and generating means for applying signals at said secondmentioned frequency to said means for processing and to said means for applying.
Claim 3
Dependent Claim
163 words
In combination, a multi-axial-mode laser comprising a cavity, and a modulator positioned within said cavity; a main feedback loop comprising means for extracting a signal from said laser cavity at the frequency that corresponds to the average axial-mode spacing of the laser, and means for applying said extracted signal to said modulator to drive said laser at or near the average mode-spacing frequency in the phase-locked region of operation of said laser to achieve mode-locked operation; a dither signal generator for applying a low frequency signal to said main loop; and an auxiliary feedback loop comprising means for extracting from said laser cavity any dither signal component in the laser output, and means responsive to said extracted dither signal component and to the output of said dither signal generator for applying a compensating signal to said main loop to maintain said laser, despite the occurrEnce of perturbations in said combination, at or near the midpoint of the operating range in which mode-locking occurs.
Claim 4
Dependent Claim
163 words
In combination, a multi-axial-mode laser comprising a cavity, and a modulator positioned within said cavity; a main feedback loop comprising means for extracting a signal from said laser cavity at the frequency that corresponds to the average axial-mode spacing of the laser, and means for applying said extracted signal to said modulator to drive said laser at or near the average mode-spacing frequency in the phase-locked region of operation of said laser to achieve mode-locked operation; a dither signal generator for applying a low frequency signal to said main loop; and an auxiliary feedback loop comprising means for extracting from said laser cavity any dither signal component in the laser output, and means responsive to said extracted dither signal component and to the output of said dither signal generator for applying a compensating signal to said main loop to maintain said laser, despite the occurrEnce of perturbations in said combination, at or near the midpoint of the operating range in which mode-locking occurs.
Claim 5
Dependent Claim
65 words
A combination as in claim 2 further including means responsive to said means for extracting a signal from said cavity at the frequency that corresponds to the average axial-mode spacing of the laser for doubling said average mode-spacing frequency, and means for applying signals at said doubled frequency to said modulator simultaneously with the application to said modulator of signals at said average mode-spacing frequency.
Claim 6
Dependent Claim
22 words
A combination as in claim 3 wherein said means for applying a compensating signal to said main loop comprises a phase-sensitive detector.
Claim 7
Dependent Claim
16 words
A combination as in claim 4 wherein said main feedback loop is of the oscillator type.
Claim 8
Dependent Claim
22 words
A combination as in claim 5 wherein said compensating signal is applied to a phase-shifting network included in said oscillator-type feedback loop.
Claim 9
Dependent Claim
16 words
A combination as in claim 4 wherein said main feedback loop is of the servo type.
Claim 10
Dependent Claim
22 words
A combination as in claim 7 wherein said compensating signal is applied to a summing amplifier included in said servo-type feedback loop.
Claim 11
Dependent Claim
130 words
In combination, a multi-axial-mode laser comprising a cavity, and a modulator positioned within said cavity; a feedback loop comprising means for extracting a signal from said laser cavity at the frequency that corresponds to the average axial-mode spacing of the laser, and means for applying said extracted signal to said modulator to drive said laser at or near the average mode-spacing frequency in the phase-locked region of operation of said laser to achieve mode-locked operation; means responsive to said means for extracting a signal from said cavity at the frequency that corresponds to the average axial-mode spacing of the laser for doubling said frequency; and means for applying signals at said doubled frequency to said modulator simultaneously with the application to said modulator of signals at said average mode-spacing frequency.
Claim 12
Dependent Claim
130 words
In combination, a multi-axial-mode laser comprising a cavity, and a modulator positioned within said cavity; a feedback loop comprising means for extracting a signal from said laser cavity at the frequency that corresponds to the average axial-mode spacing of the laser, and means for applying said extracted signal to said modulator to drive said laser at or near the average mode-spacing frequency in the phase-locked region of operation of said laser to achieve mode-locked operation; means responsive to said means for extracting a signal from said cavity at the frequency that corresponds to the average axial-mode spacing of the laser for doubling said frequency; and means for applying signals at said doubled frequency to said modulator simultaneously with the application to said modulator of signals at said average mode-spacing frequency.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-23 | 1976-07-24 | 1977-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-23 | 1980-07-24 | 1981-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-23 | 1984-07-24 | 1985-01-23 | $7700.00 | Window Closed / Lapsed |