Polarization insensitive optical signal reception

A method of processing a polarised local oscillator optical signal of a coherent optical detector used for reception of an optical signal carrying optical information comprising:

• altering the polarisation state of the polarised local oscillator signal in sequential time intervals in response to a control signal to provide a processed local oscillator signal with substantially orthogonal polarisation states alternating sequentially according to the frequency of said control signal,
• said control signal being at a sufficiently high frequency such that the information on the information signal is detectable using at least one of the alternating orthogonal states of the processed local oscillator signal.

An optical device for processing an optical signal used for information transmission or reception, said device comprising:

• control means for providing a control signal and means for altering the polarisation state of an input optical signal under control of the control means to provide an output optical signal with substantially orthogonal polarisation states alternating sequentially according to the frequency of said control signal;
• the control means including means for setting the control signal at a sufficiently high frequency such that the information is independently detectable in either one of the alternating orthogonal states.