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US4631498A
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US
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CW Laser wavemeter/frequency locking technique
Assignee: Agilent Technologies Inc
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Filing: 1985-04-26
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Granted: 1986-12-23
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Expires: 2005-04-26
Abstract
Abstract A wavemeter/frequency locking technique suitable for indirectly locking an optical frequency f 0 to a radio frequency f 1 or for locking the radio frequency to the optical frequency. A beam of optical frequency f 0 is phase modulated by a signal of average frequency f 1 that is itself modulated at frequency f 2 . The modulated beam is passed through a filter to a detector to produce a detector output signal that has components at linear integral sums of f 1 and f 2 . A pair of control signals are generated that are proportional to the amplitude of two of the components of the detector output signal. These control signals are separately used in a pair of servo loops to separately establish fixed values of f 0 /f f and f 1 /f f , where f f is a characteristic frequency of the filter. A method is presented for stepping the value of f 0 /f f to another value and measuring f 1 /f 2 at each of these values, thereby enabling the value of f 0 to be determined.
Inventors
- 👤 Gregory M. Cutler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:32
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/10; H01S3/13; H01S3/139; H01S3/1398; G; G02; G02F; G02F2/00; H01S3/005; H01S3/0064; H03; H03L; H03L7/00
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
130 words
A frequency locking circuit comprising: a source of a beam of continuous wave, coherent radiation of frequency f 0 ; means for phase modulating the beam, in response to a subcarrier of frequency f 1 that is itself modulated, to produce a phase modulated beam; a filter through which the phase modulated beam passes, said filter having a transfer function that has a characteristic frequency f f ; a detector, responsive to the beam after the beam passes through the filter to produce a detector output signal; means, responsive to the detector output signal, for adjusting the ratio of f 0 /f f to a fixed value L; and means, responsive to the detector output signal, for adjusting the ratio of f 1 /f f to a fixed value K.
Claim 2
Dependent Claim
130 words
A frequency locking circuit comprising: a source of a beam of continuous wave, coherent radiation of frequency f 0 ; means for phase modulating the beam, in response to a subcarrier of frequency f 1 that is itself modulated, to produce a phase modulated beam; a filter through which the phase modulated beam passes, said filter having a transfer function that has a characteristic frequency f f ; a detector, responsive to the beam after the beam passes through the filter to produce a detector output signal; means, responsive to the detector output signal, for adjusting the ratio of f 0 /f f to a fixed value L; and means, responsive to the detector output signal, for adjusting the ratio of f 1 /f f to a fixed value K.
Claim 3
Dependent Claim
27 words
A frequency locking circuit as in claim 1, further comprising means for stepping L from an initial value L i to a final value L f .
Claim 4
Dependent Claim
19 words
A frequency locking circuit as in claim 1 wherein the modulation of the subcarrier is substantially pure phase modulation.
Claim 5
Dependent Claim
19 words
A frequency locking circuit as in claim 1 wherein the modulation of the subcarrier is substantially pure amplitude modulation.
Claim 6
Dependent Claim
36 words
A frequency locking circuit as in claim 1 wherein the filter is a Michelson interferometer, whereby the filter has a low level of dispersion so that the circuit is particularly suitable for use in a wavemeter.
Claim 7
Dependent Claim
31 words
A frequency locking circuit as in claim 1 wherein the filter is a Fabry-Perot interferometer, whereby the circuit has great sensitivity so that the circuit is particularly useful in signal stabilization.
Claim 8
Dependent Claim
29 words
A frequency locking circuit as in claim 6 wherein the Fabry-Perot interferometer has at least three mirrors configured to avoid reflecting light back to the source of the beam.
Claim 9
Dependent Claim
25 words
A frequency locking circuit as in claim 1 wherein K is an odd multiple of 1/2 and L is also an odd multiple of 1/2.
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) | 1989-12-22 | 1990-06-23 | 1990-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-12-22 | 1994-06-23 | 1994-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-12-22 | 1998-06-23 | 1998-12-23 | $7700.00 | Window Closed / Lapsed |