Lucent Technologies Inc.

At&t Bell Laboratories

Kalpendu Ranjitrai Shastri

Thaddeus John Gabara

Alfred E Dunlop

Mihai Banu

Wilhelm Carl Fischer

David A Snyder

James J Royer

There is disclosed a laser driver or transmitter in which a drive current is generated by monitoring the temperature of an integrated circuit that generates drive current for the laser. The temperature sensed at the integrated circuit is transformed to a corresponding temperature at the laser. A drive current is generated for the laser that is dependent on the corresponding temperature at the laser.

Laser driver with temperature sensor on an integrated circuit

A clock recovery circuit is coupled to an elastic storage circuit such as a FIFO circuit. More specifically, a first input of the elastic storage circuit is electrically connected to an output of the clock recovery circuit. A second input for accepts a data signal representing an input data stream from a communications medium. A third input accepts a local clock signal. The resultant circuit may be used in receiver's for communications systems to help alleviate the problems of frequency mismatch and jitter.

Clock recovery circuit

A laser driver includes a reference circuit, which may be a bandgap reference, mounted in thermal contact with the laser. The reference produces a current component Iptat that is proportional to the absolute temperature. The modulation current is proportional to Iptat, which slowly with temperature, up to a certain junction temperature (e.g., 65 to 70 degrees C.). Above that temperature, the modulation current increases more rapidly by adding an additional current component Icomp. This provides for the required increase in modulation current to compensate for temperature variations in the laser output. This technique allows the laser to be operated without cooling (as by a thermoelectric cooler) in many applications. The laser driver may optionally include circuitry to provide a bias current, which may be controlled by a backface monitor or threshold detector.

Laser driver with temperature compensation

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Allentown, PA, United States of America

Kalpendu Ranjitrai Shastri