Patent ID: 7792436
Filing Date: 2010-09-07
Classification: H04B,H04L

Abstract:
1. An optical receiver comprising: a light branching unit branching a differential M-phase shift keying signal light beam into first, second, third and fourth signal light beams, a delay adjusting unit relatively giving a delay time difference of one symbol between the first signal light beam and the second signal light beam and between the third signal light beam and the fourth signal light beam and also giving a relative phase difference of almost odd number times of π/2 in signal light wavelength between the first signal light beam and the third signal light beam, and thereafter outputting the first, second, third and fourth signal light beams, a demodulating unit outputting at least two demodulated light signals through respective interferences, on one common plane, between the first signal light beam and the second signal light beam output from the delay adjusting unit, and between the third signal light beam and the fourth signal light beam output from the delay adjusting unit, and at least two light detectors for converting at least two demodulated light signals of said at least two demodulated light signals output by the demodulating unit into electrical signals, wherein the demodulating unit is provided with a half-mirror on one plane where an interference of the first and second signal light beams and an interference of the third and fourth signal light beams are generated.