Patent ID: 7573641

Claim:
An optical hybrid, comprising: means for splitting a signal light beam (S) into a reflected signal light beam (RS) and a transmitted signal light beam (TS); means for splitting a reference light beam (L) into a reflected light beam (RL) and a transmitted light beam (TL); and means for combining pairs of said RS, TS, RL and TL to produce a plurality of combined output beams comprising an S+L beam, an S+jL beam, an S−L beam and an S jL beam, wherein the phase difference between said S light beam and said L light beam in said S+jL beam, said S−L beam and said S−jL beam, with respect to the phase difference between said S light beam and said L light beam in said S+L beam, is about 90 degrees, 180 degrees and 270 degrees, respectively; and wherein said means for splitting a signal light beam and said means for splitting a reference light beam together comprise a first beam splitter comprising a first face, a second face, a third face, a fourth face and an internal reflecting/transmitting coating.