Polarization Independent Coherent Optical Receiver.

This paper describes an optical heterodyne receiver for DPSK signals which can accept an optical signal having an arbitrary polarization state. This is achieved by splitting the received signal between two orthogonal polarization axes and processing the resulting two signals as in a conventional DPSK heterodyne receiver. The sum of the two demodulated signals provides a baseband signal independent of the polarization state of the received optical signal.