Polarization-insensitive coherent receiver using a double balanced optical hybrid system.

A prototype polarization-insensitive double balanced receiver for coherent lightwave communication is demonstrated and described in this paper. This receiver has been tested in a 40 Mb/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 polarization. The cause of this variation is also discussed.