Patent ID: 7864433
Filing Date: 2011-01-04
Classification: G02B

Abstract:
1. 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 light beams 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 said S and L beams have a phase difference of θ degrees, and wherein a phase shift of X degrees, 0≦X≦180 degrees, is introduced such that a pair of said RS, TS, RL and TL beams interfering to produce said S+L beam have a phase difference of θ degrees, a pair of said RS, TS, RL and TL beams interfering to produce said S+jL beam have a phase difference of θ+X degrees, a pair of said RS, TS, RL and TL beams interfering to produce said S−L beam have a phase difference of θ+180 degrees, and a pair of said RS, TS, RL and TL beams interfering to produce said S−jL beam has a phase difference of θ+180+X degrees; and wherein said means for splitting said beam S and said beam L together comprises a first beam splitter comprising a first face, a second face, a third face, a fourth face and an internal reflecting/transmitting coating.