Patent ID: 8355128

Claim:
A feedforward controller for controlling the polarization state of an optical signal, the feedforward controller comprising: an optical input for receiving an optical input signal having an input polarization state; an optical input sampler for sampling the optical input signal to provide one or more signals representative of the input polarization state of the optical input signal; an optical output for transmitting an optical output signal having an output polarization state; an output sampler sampler for sampling the optical output signal to provide one or more signals representative of the output polarization state of the optical output signal; and a polarization controller coupled to the optical input and the optical output; a transfer function determiner comprising a signal processor coupled to the optical input sampler and to the optical output sampler, the signal processor determining a characteristic polarization transfer function of the feedforward controller from the input and output polarization states by processing representative signals from the optical input sampler and the optical output sampler, and generating one or more control signals; and wherein the polarization controller is adapted to modify the polarization state of light passing therethrough in dependence on the one or more control signals received from the signal processor.