US3869680A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dually mode-locked nd:yag laser
Assignee: National Aeronautics and Space Administration
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Filing: 1973-08-31
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Granted: 1975-03-04
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Expires: 1993-08-31
Abstract
Abstract A dually mode-locked laser system is disclosed, the laser system being of the general type including a laser cavity defined by a pair of at least partially relecting mirrors with a laser material disposed in the cavity. A loss modulator mode-locking element and a phase modulator mode-locking element are disposed in the laser cavity in optical series with one another. Modulation drive signals are provided for each mode-locking element such that each mode-locking element produces an output pulse train of substantially the same repetition rate and wherein the output pulse train is in a timed inter-relationship such that the pulses pass through both mode-locking elements without being extinguished. The loss mode-locker is driven at a low level so that relaxation oscillations do not occur and forces the pulses generated by the phase mode-locker to maintain a constant phase relative to the mode-lock drive signal. The laser system can be run both open loop and with a phase-lock stabilization feedback loop.
Inventors
- 👤 James C Administrator Fletcher
- 👤 John Osmundson
- 👤 H Edward Rowe
- 👤 Dominick Santarpia
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 00:39
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/10; H01S3/11; H01S3/1106; H01S3/1109; H01S3/13; H01S3/131; H01S3/1312; H01S3/136
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
136 words
A method of mode-locking a pulsed laser system of the type including a laser cavity defined by a pair of at least partially reflecting mirrors with an active gain lasing medium disposed in the cavity, said method comprising the steps of: inserting a loss-modulator mode-locking element and a phase modulator mode-locking element into the laser cavity in optical series with one another to effect simultaneous loss modelocking and phase mode-locking; generating modulation drive signals to each mode-locking element such that each mode-locking element produces an output pulse train of substantially the same repetition rate; and timing the mode-locked pulses so produced such that the pulses leaving the phase modulator mode-locking element and propagating toward the loss modulator mode-locking element arrive at the loss modulator mode-locking element when transition through the loss mode-locker is at a maximum.
Claim 2
Independent Claim
136 words
A method of mode-locking a pulsed laser system of the type including a laser cavity defined by a pair of at least partially reflecting mirrors with an active gain lasing medium disposed in the cavity, said method comprising the steps of: inserting a loss-modulator mode-locking element and a phase modulator mode-locking element into the laser cavity in optical series with one another to effect simultaneous loss modelocking and phase mode-locking; generating modulation drive signals to each mode-locking element such that each mode-locking element produces an output pulse train of substantially the same repetition rate; and timing the mode-locked pulses so produced such that the pulses leaving the phase modulator mode-locking element and propagating toward the loss modulator mode-locking element arrive at the loss modulator mode-locking element when transition through the loss mode-locker is at a maximum.
Claim 3
Dependent Claim
29 words
A method as defined in claim 1, wherein the step of timing the mode-locked pulses comprises phase shifting the modulation drive signals to one of the two mode-locking elements.
Claim 4
Dependent Claim
24 words
A method as defined in claim 1, wherein at least one of the mode-locking elements is positioned adjacent a mirror within the laser cavity.
Claim 5
Dependent Claim
34 words
A method as defined in claim 1, further including the step of stabilizing the mode-locked pulses by providing a phase lock loop responsive to the laser output to control the modulation drive signals generated.
Claim 6
Dependent Claim
79 words
In a pulsed laser system wherein an active gain lasing medium is disposed in a laser cavity defined by a pair of at least partially reflecting mirrors, the improvement whereby dual mode-locking of the laser output pulses is obtained, said improvement comprising, in combination: a loss modulator mode-locking element and a separate phase modulator mode-locking element disposed in the laser cavity in optical series with one another; and generating means for generating modulation drive signals to each mode-locking element.
Claim 7
Dependent Claim
79 words
In a pulsed laser system wherein an active gain lasing medium is disposed in a laser cavity defined by a pair of at least partially reflecting mirrors, the improvement whereby dual mode-locking of the laser output pulses is obtained, said improvement comprising, in combination: a loss modulator mode-locking element and a separate phase modulator mode-locking element disposed in the laser cavity in optical series with one another; and generating means for generating modulation drive signals to each mode-locking element.
Claim 8
Dependent Claim
23 words
A system as defined in claim 5, wherein at least one of said mode-locking elements is disposed adjacent a mirror of said pair.
Claim 9
Dependent Claim
53 words
A system as defined in claim 6, wherein said generating means includes oscillator means for producing modulation drive signals having a different frequency to each respective mode-locking element, the frequency difference between the respective drive signals being selected to effect an output pulse from each mode-locking element of substantially the same repetition rate.
Claim 10
Dependent Claim
69 words
A system as defined in claim 7, wherein said generating means further includes a phase shifter disposed between the output of said oscillator means and one of said mode-locking elements for shifting the phase of the modulation drive signal to said one mode-locking element whereby the output pulses of each mode-locking element are produced in a timed inter-relationship so as to pass through both mode-locking elements without being extinguished.
Claim 11
Dependent Claim
26 words
A system as defined in claim 8, further including a feedback stabilization loop means for modifying the modulation drive signals in response to the laser output.
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) | 1978-03-03 | 1978-09-02 | 1979-03-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-03 | 1982-09-02 | 1983-03-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-03 | 1986-09-02 | 1987-03-04 | $7700.00 | Window Closed / Lapsed |