90 degree optical hybrid for coherent receivers

The power losses and noise of the present 90-deg hybrid optical coherent receiver are minimized through the use of a six-port configuration in which channel balancing is furnished by half-wave plates. The 90-deg shift is introduced between orthogonally polarized beam components by a quarter-wave plate, and the output ports are phase-shifted by 180 deg through the sole use of the half-wave plates and polarizing beam splitters.