EP0221710A2
Expired / Lapsed
EP
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Apparatus for controlling the power of a laser
Assignee: AT&T Inc
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Filing: 1986-10-20
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Granted: —
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Expires: 2006-10-20
Abstract
Abstract The power output from a laser transmitter is maintained within predetermined levels. These levels are maintained at fixed percentages on either side of the average laser output power which is transmitted, regardless of variations in ambient temperature. This is achieved by coupling 85 the bias current control loop 90 to the modulation current control circuit 60.
Inventors
- 👤 Richard Joseph Lisco
- 👤 Josef Ocenasek
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 13:46
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683; H01S5/06832
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
94 words
Apparatus for controlling the power of a laser (50) over a predetermined range of ambient temperatures, said apparatus being CHARACTERIZED BY a modulator (20) for receiving data input as logical 1's and 0's and for converting the logical 1's and 0's into corresponding levels of a laser modulation current, a backface monitor (120) for generating a current proportional to the power output of the laser, means (90) for controlling the laser bias current in dependence on the backface monitor current, and means (60) for controlling the modulation current in dependence on the bias current.
Claim 2
Dependent Claim
94 words
Apparatus for controlling the power of a laser (50) over a predetermined range of ambient temperatures, said apparatus being CHARACTERIZED BY a modulator (20) for receiving data input as logical 1's and 0's and for converting the logical 1's and 0's into corresponding levels of a laser modulation current, a backface monitor (120) for generating a current proportional to the power output of the laser, means (90) for controlling the laser bias current in dependence on the backface monitor current, and means (60) for controlling the modulation current in dependence on the bias current.
Claim 3
Dependent Claim
101 words
Apparatus as claimed in claim 1 including means (122, 124) for converting the backface monitor current into a voltage, and wherein the means (90) for controlling the bias current includes means (108, 110, 112) for integrating the backface monitor voltage, means for converting the integrated voltage to a current, said means including first (98) and second (84) transistors in cascade, the collector of the second transistor receiving bias current from the laser (50) and the current at the emitter of the second transistor being proportional to the collector current, and means (86) for converting the emitter current to an emitter voltage.
Claim 4
Dependent Claim
97 words
Apparatus as claimed in claim 2 wherein the means for controlling the modulation current includes a third transistor (64) having the laser modulation current delivered at the collector thereof, and an operational amplifier (78) having two inputs, one of said inputs (79) being adapted to receive a feedback voltage signal which is proportional to the modulation current from the emitter of the third transistor, and the second input (77) being adapted to receive a reference voltage signal modified by the emitter voltage from the second transistor, the operational amplifier providing the base signal for the third transistor.
References Cited (Backward Citations)
No citation records indexed.
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