Eastman-Kodak Company

Daniel J Phelps

Daniel C Abbas

Frank T Smith

David M McVay

David J Lawrence

Karen L Herczeg

Kimberley C Bell

Providing thermal compensation for laser diodes used in intensity modulated applications by using active feedback. A PIN diode serves as a laser light output sensor for the closed loop feedback system. The input from the PIN diode is convened into a voltage and then fed into a feedback amplifier. The PIN diode current is slightly dependent upon the temperature due to transmission effects of materials within the laser diode assembly. A temperature voltage signal generated by a semiconductor temperature sensor may be used as a second input to the feedback amplifier. The output of this amplifier is sampled at periodic intervals such as once a scan line, by a sample and hold amplifier. The output of the sample and hold amplifier is added to a data dependent modulated current reference in a summing amplifier. The output of the summing amplifier is the resultant sensor and provides an input reference to the laser driver integrated circuit.

Thermal compensation for laser diodes using active feedback

An efficient light emitting diode is disclosed wherein the spatial distribution of emitted radiation is highly uniform. In accordance with the present invention, a transparent electrode is used to couple current to the light emitting diode junction in a manner that minimizes the resistance at the interface between the transparent electrode and semiconductor diode material. Specifically, it has been found that the interface resistance is significantly reduced, and device efficiency thus increased, by forming a thin metal-based layer at such interface and/or by annealing the transparent electrode after formation on the device.

Transparent electrode light emitting diode and method of manufacture

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Rochester, NY, United States of America

Daniel J Phelps