US4357713A
Expired / Lapsed
US
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Method and apparatus for reduction of modal noise in fiber optic systems
Assignee: United States Department of the Army
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Filing: 1979-09-12
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Granted: 1982-11-02
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Expires: 1999-09-12
Abstract
Abstract A dithering means is applied to a laser diode to provide dither modulation along with a signal input thereto. Modal noise, otherwise generated by the system, is reduced by the introduction of dither modulation.
Inventors
- 👤 James C. Blackburn
- 👤 Jonathan Vanderwall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 04:39
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/50; H04B10/501; H04B10/503; H04B10/504
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
85 words
An analogue optical signal system with reduced modal noise comprising: a source for generating an optical output signal linearly related to a high frequency wide-band input signal; means for applying a biasing signal to said source wherein said source is biased to operate above threshold whereby said optical signal system operates as an analogue system; transmission means for transmitting said output signal to a receiver; and means for applying a high frequency signal above the Nyquist rate of said transmitted signal to said biasing signal.
Claim 2
Dependent Claim
85 words
An analogue optical signal system with reduced modal noise comprising: a source for generating an optical output signal linearly related to a high frequency wide-band input signal; means for applying a biasing signal to said source wherein said source is biased to operate above threshold whereby said optical signal system operates as an analogue system; transmission means for transmitting said output signal to a receiver; and means for applying a high frequency signal above the Nyquist rate of said transmitted signal to said biasing signal.
Claim 3
Dependent Claim
24 words
An analogue optical signal system as recited in claim 1, wherein said high frequency signal is above the optical response band of said receiver.
Claim 4
Dependent Claim
23 words
An analogue optical signal system as recited in claim 2, wherein said source for generating a linear output signal comprises an injection laser.
Claim 5
Dependent Claim
17 words
An analogue optical signal system as recited in claim 3, wherein said transmission means comprise fiber optics.
Claim 6
Independent Claim
89 words
A method of reducing modal noise in an analogue optical signal system comprising the steps of: applying an input signal current to a wavelength - current dependent source of single mode optical radiation; applying a biasing signal to said source wherein said source is biased above the threshold whereby said source generates an optical output signal linearly related to said input signal; transmitting said output signal to an optical receiver; and modulating said biasing signal with a high frequency signal above the Nyquist rate of said transmitted output signal.
Claim 7
Independent Claim
89 words
A method of reducing modal noise in an analogue optical signal system comprising the steps of: applying an input signal current to a wavelength - current dependent source of single mode optical radiation; applying a biasing signal to said source wherein said source is biased above the threshold whereby said source generates an optical output signal linearly related to said input signal; transmitting said output signal to an optical receiver; and modulating said biasing signal with a high frequency signal above the Nyquist rate of said transmitted output signal.
Claim 8
Dependent Claim
22 words
A method, as recited in claim 5, wherein said high frequency signal is above the optical response band of said optical receiver.
Claim 9
Dependent Claim
19 words
A method, as recited in claim 6, wherein said source of single mode optical radiation comprises an injection laser.
Claim 10
Dependent Claim
17 words
A method, as recited in claim 7, wherein the step of transmitting is accomplished via fiber optics.
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) | 1985-11-01 | 1986-05-03 | 1986-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-11-01 | 1990-05-03 | 1990-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-11-01 | 1994-05-03 | 1994-11-02 | $7700.00 | Window Closed / Lapsed |