BIAS CONTROLLER FOR AN OPTICAL MODULATOR

摘要

This application relates to a bias controller (17) for an optical modulator (1). The modulator includes a bias electrode (9) that is operable when appropriately biased by an applied bias voltage to configure the modulator to operate at quadrature, and the bias controller comprises: means (21) for generating power signals indicative of the optical output power of the modulator (1); and a processor (27) operably connected to the generating means (21) and said bias electrode (9) and arranged to receive said power signals from said generating means (21) and to control the bias voltage applied to said bias electrode (9). The processor (27) is configured to vary the bias voltage applied to said bias electrode (9) and to determine from power signals received from said generating means (21) a peak optical output power for said modulator (1), and to determine in dependence upon said peak optical power a target optical power for quadrature with reference to a store of predetermined values for peak output power and respective corresponding values of target optical power for quadrature. Other embodiments relate to a multi-channel bias controller, and to a method for controlling voltage bias in a modulator.