Patent ID: 7087882

Claim:
A fiber-optic transceiver for use in optical communications where the fiber-optic transceiver may receive optical signals of varying powers, the fiber-optic transceiver comprising: an avalanche photodiode comprising: a gain layer; an absorption layer; and a field control layer disposed between the gain layer and the absorption layer, the field control layer having a doping thickness product that determines a dynamic range and is a product of a density of a dopant and a thickness of the field control layer; a power supply that supplies a range of bias voltages to the avalanche photodiode, wherein the doping thickness product of the field control layer causes the avalanche photodiode to operate in an avalanche region when biased by a bias voltage in the range of bias voltages and wherein a relation between the doping thickness product and an avalanche photodiode punch through voltage, breakdown voltage and dynamic range is such that for a first doping thickness product that is less than a second doping thickness product: a punch through voltage associated with the first doping thickness product is relatively lower than a punch through voltage associated with the second doping thickness product; a breakdown voltage associated with the first doping thickness product is relatively greater than a breakdown voltage associated with the second doping thickness product; and a dynamic range associated with the first doping thickness product is relatively greater than a dynamic range associated with the second doping thickness product; and a feedback mechanism that controls the bias voltage in response to the current through the avalanche photodiode.