Patent US4995045A successfully refreshed from Google Patents.
US4995045A
Expired / Lapsed
US
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Laser control circuit
Assignee: Nortel Networks Ltd
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Filing: 1990-02-01
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Granted: 1991-02-19
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Expires: 2010-02-01
Abstract
Abstract A laser diode control circuit maintains a desired average output power of the laser diode by detecting the optical output, amplifying the detected output, and controlling a bias current of the laser diode accordingly. A pilot tone is combined with the detected output and amplified therewith, and the amplified level of the tone is detected and used to control a modulation current for the laser diode. In one described arrangement the laser diode is controlled to have a high extinction ratio with the bias current at the knee of the diode's characteristic curve, and in another arrangement a lower extinction ratio is provided with the bias current above the knee.
Inventors
- 👤 Gregory S. Burley
- 👤 Kim B. Roberts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:33
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683; H01S5/06832
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
75 words
A laser diode control circuit comprising: first control means, including an amplifier, having an input and an output, for controlling a bias current for a laser diode; means for supplying a pilot signal to the input of the amplifier; and second control means connected to the output of the amplifier and responsive to an amplified level of the pilot signal at the output of the amplifier for controlling a modulation current of the laser diode.
Claim 2
Dependent Claim
75 words
A laser diode control circuit comprising: first control means, including an amplifier, having an input and an output, for controlling a bias current for a laser diode; means for supplying a pilot signal to the input of the amplifier; and second control means connected to the output of the amplifier and responsive to an amplified level of the pilot signal at the output of the amplifier for controlling a modulation current of the laser diode.
Claim 3
Dependent Claim
44 words
A control circuit as claimed in claim 1 wherein the second control means comprises detector means for detecting the amplified level of the pilot signal and producing an output voltage representing the amplified level of the pilot signal, for comparison with a reference voltage.
Claim 4
Dependent Claim
29 words
A control circuit as claimed in claim 2 wherein the pilot signal comprises a pilot tone and the detector means for detecting the pilot signal comprises a synchronous detector.
Claim 5
Dependent Claim
21 words
A control circuit as claimed in claim 2 wherein the detector means for detecting the pilot signal comprises a low-pass filter.
Claim 6
Dependent Claim
46 words
A control circuit as claimed in claim 2 wherein the second control means further comprises means for comparing the output voltage, from the detector means, with a reference voltage to provide a control voltage and means for controlling the modulation current responsive to the control voltage.
Claim 7
Dependent Claim
38 words
A control circuit as claimed in claim 2 wherein the second control means further comprises means for amplifying the output voltage to provide a control voltage and means for controlling the modulation current responsive to the control voltage.
Claim 8
Dependent Claim
44 words
A control circuit as claimed in claim 6 wherein the second control means further comprises means responsive to the output voltage and to a reference voltage for producing a further control voltage to which the means for controlling the modulation current is also responsive.
Claim 9
Independent Claim
89 words
A method of controlling a laser diode comprising the steps of: detecting an output of the laser diode; providing a pilot signal; combining the detected output with the pilot signal and amplifying the combined signal to produce an amplified signal having, as a component thereof, an amplified level of the pilot signal; controlling a bias current of the laser diode in dependence upon the amplified signal; and controlling a modulation current for the laser diode in dependence upon the amplified level of the pilot signal in the amplified signal.
Claim 10
Independent Claim
89 words
A method of controlling a laser diode comprising the steps of: detecting an output of the laser diode; providing a pilot signal; combining the detected output with the pilot signal and amplifying the combined signal to produce an amplified signal having, as a component thereof, an amplified level of the pilot signal; controlling a bias current of the laser diode in dependence upon the amplified signal; and controlling a modulation current for the laser diode in dependence upon the amplified level of the pilot signal in the amplified signal.
Claim 11
Dependent Claim
44 words
A method as claimed in claim 8 wherein the step of controlling the modulation current comprises the steps of: detecting the amplified level of the pilot signal in the amplified signal; and comparing the detected level of the pilot signal with a reference level.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-18 | 1994-08-20 | 1995-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-18 | 1998-08-20 | 1999-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-18 | 2002-08-20 | 2003-02-19 | $7700.00 | Window Closed / Lapsed |