Polarisation-insensitive coherent receiver using a double balanced optical hybrid system

Abstract

A prototype polarisation-insensitive double balanced receiver for coherent lightwave communication is demonstrated and described in the letter. This receiver has been tested in a 40Mbit/s DPSK self-heterodyne system. The maximum variation in the amplitude of the recovered data is only about 0.8 dB under random variation of the signal polarisation. The cause of this variation is also discussed.