Patent US4218776A successfully refreshed from Google Patents.
US4218776A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Parametric optical detector
Assignee: AT&T Inc
•
Filing: 1979-04-02
•
Granted: 1980-08-19
•
Expires: 1999-04-02
Abstract
Abstract Improved signal to noise performance is obtained in an optical detector circuit (10) by impressing a high frequency (ω p ) pumping signal across a varactor photodetector (11) and extracting an output signal that includes the band of frequencies ω p ±ω m , where ω m is the maximum modulation frequency to be recovered by the detector. The modulation signal is recovered in an appropriate amplitude demodulator (15).
Inventors
- 👤 Harold Seidel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:00
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/60; H04B10/66; H04B10/69; H04B10/697; H04B10/6973
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
78 words
An optical detector circuit (10) comprising: a varactor photodetector (11); a source of high frequency signal (13) coupled (14) to said circuit (10); and means (12) for extracting an output signal from said circuit; CHARACTERIZED IN THAT: said means (12) is tuned to a band of frequencies including ω p ±ω m , where ω p is the frequency of said high frequency source and ω m is the maximum modulation frequency to be recovered by said detector.
Claim 2
Dependent Claim
78 words
An optical detector circuit (10) comprising: a varactor photodetector (11); a source of high frequency signal (13) coupled (14) to said circuit (10); and means (12) for extracting an output signal from said circuit; CHARACTERIZED IN THAT: said means (12) is tuned to a band of frequencies including ω p ±ω m , where ω p is the frequency of said high frequency source and ω m is the maximum modulation frequency to be recovered by said detector.
Claim 3
Dependent Claim
32 words
The circuit according to claim 1 wherein the output of said means (12) is coupled to a demodulator (15) for recovering any modulation impressed upon the optical signal incident upon said photodetector.
Claim 4
Dependent Claim
33 words
The circuit according to claim 1 wherein said photodetector (20) is located in one arm of a bridge circuit (28) for suppressing the component of high frequency pump signal in the detector output.
Claim 5
Dependent Claim
35 words
The circuit according to claim 3 wherein the optical detector output signal is coupled to a mixer 32 along with a component of pump frequency for recovering any modulation impressed upon an input optical signal.
References Cited (Backward Citations)
US3196274A
Cited
US3379888A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-08-19 | 1984-02-18 | 1984-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-08-19 | 1988-02-18 | 1988-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-08-19 | 1992-02-18 | 1992-08-19 | $7700.00 | Window Closed / Lapsed |