Automatic setting of laser diode bias current

Abstract

Threshold current may be determined and one or more bias sources may be programmed in a laser drive circuit. For example, a laser diode emits light along first and second optical paths. A polarizer is positioned in the first optical path between the laser diode and a first detector, which outputs a first detector signal corresponding to the measured optical power of polarized light. A second detector monitors light along the second optical path and provides a second detector signal. A bias compensation circuit receives the first and second detector signals and provides a bias current control signal, which is utilized to program a bias current source supplied to the laser diode. Additionally, multiple polarizer devices may be utilized e.g., a first polarizer in a first optical path aligned with the laser beam and a second polarizer in a second optical path aligned substantially orthogonal to the polarization of the laser beam.