Patent US4277846A successfully refreshed from Google Patents.
US4277846A
Expired / Lapsed
US
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Circuit for stabilizing the output of an injection laser
Assignee: AT&T Inc
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Filing: 1979-12-27
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Granted: 1981-07-07
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Expires: 1999-12-27
Abstract
Abstract A digitally modulated injection laser is provided with a control circuit to keep constant both its "zero" and "one" light output values despite changes in duty cycle and aging effects. The circuit includes one branch which maintains constant the average light value and another branch which maintains constant the difference between the "one" value and the average light value.
Inventors
- 👤 Fang-Shang Chen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:04
CPC Classifications
H; H01; H01M; H01M6/00; H01M6/42; H01M6/46; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683; H01S5/06835
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
172 words
A circuit for maintaining substantially constant the light output of the "ON" and "OFF" states of an injection laser to be supplied with an input signal train for use as the transmitter in a digital lightwave system comprising means for monitoring the light output from a laser and developing a photovoltage which is a measure of such output, control means supplied both with said photovoltage and with a voltage which is a measure of the duty cycle of the input train for providing a bias current to the laser which is a measure of the average light output compensated for the duty cycle, control means supplied both with said photovoltage and with a voltage which is a measure of the duty cycle of the input train for providing a control voltage which is a measure of the difference between the peak light output and the average light output compensated for the duty cycle, and means supplied both which the input train and said control voltage for providing modulating current to the laser.
Claim 2
Dependent Claim
172 words
A circuit for maintaining substantially constant the light output of the "ON" and "OFF" states of an injection laser to be supplied with an input signal train for use as the transmitter in a digital lightwave system comprising means for monitoring the light output from a laser and developing a photovoltage which is a measure of such output, control means supplied both with said photovoltage and with a voltage which is a measure of the duty cycle of the input train for providing a bias current to the laser which is a measure of the average light output compensated for the duty cycle, control means supplied both with said photovoltage and with a voltage which is a measure of the duty cycle of the input train for providing a control voltage which is a measure of the difference between the peak light output and the average light output compensated for the duty cycle, and means supplied both which the input train and said control voltage for providing modulating current to the laser.
Claim 3
Dependent Claim
43 words
A circuit in accordance with claim 1 including means supplied with the input train of pulses and deriving a pair of complementary trains of pulses, one for supply to the first-mentioned control means, and the other for supply to the second-mentioned control means.
Claim 4
Dependent Claim
43 words
A circuit in accordance with claim 1 in which the means for providing the modulating current to the laser comprises an emitter-coupled transistor pair current switch having as the current source a transistor supplied with the output of said second mentioned control means.
Claim 5
Dependent Claim
43 words
A circuit in accordance with claim 2 in which the means for providing the modulating current to the laser comprises an emitter-coupled transistor pair current switch having as the current source a transistor supplied with the output of said second mentioned control means.
References Cited (Backward Citations)
US4009385A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-07-06 | 1985-01-05 | 1985-07-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-07-06 | 1989-01-05 | 1989-07-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-07-06 | 1993-01-05 | 1993-07-07 | $7700.00 | Window Closed / Lapsed |