Measurement of the excess sensitivity penalty of a 4-diode polarization diversity coherent receiver.

A novel optical polarization-diversity coherent receiver is described and demonstrated. The receiver optical hybrid consists of three polarizing beam splitters and four PIN diodes, interconnected with polarization maintaining fibers. Measurements over arbitrary input polarizations show a receiver sensitivity of -63+-0.5 dBm for BER of 10 sup (-9) in a 40 Mb/s DPSK self-heterodyne system. This receiver sensitivity is within 1+-0.5 dB of the sensitivity of a single-channel receiver with matched signal and local oscillator polarization.