An optical receiver and an optical receiving method corresponding to a differential M phase-shift keying

摘要

PROBLEM TO BE SOLVED: To provide a compact inexpensive optical receiver capable of stably demodulating a signal light in compliance with the differential M phase shift keying (DMPSK) modulation system.;SOLUTION: The optical receiver includes: branch sections 16, 17 that branch signal lights received by first to fourth optical guide paths provided on a board and supply the branched lights; the second and third optical guide paths providing a delay time difference by about one symbol of a DMPSK modulation signal; a demodulation section 60 for two optical signals resulting from interference of respective signal lights between the first and second optical guide paths 31, 32 and between the third and fourth optical guide paths; two light receiving units for converting the two optical signals from the demodulation section into electric signals; and an optical path length variable section 50 that changes each optical path length of the two optical guide paths selected from combinations comprising the first and third optical guide paths, the first and fourth optical guide paths, and the second and third optical guide paths and arranged to one region when the wavelength of the signal light is in variation.;COPYRIGHT: (C)2007,JPO&INPIT