OPTICAL RECEIVER AND OPTICAL RECEIVING METHOD CORRESPONDING TO DIFFERENTIAL M-PHASE SHIFT MODULATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a small and low cost optical receiver capable of stably demodulating signal light following an M-phase differential phase shift modulation (DMPSK) system.

SOLUTION: The optical receiver includes: a branch part 651 for supplying nearly equal power signal light yielded by branching input light; a delay adjusting part for giving a relative-delay-time-difference corresponding to substantially 1 symbol fraction in an M-phase differential-phase-shift-modulation-signal to first and fourth signal lights; a demodulation part for demodulating at least 2 optical signals by permitting respectively signal lights to interfere in the first and second signal lights and the third and fourth signal lights; and at least two optical receivers for converting to an electric signal at least the two optical signals from the demodulation part, and in the delay adjustment part an operation point of two delay interferometer is set to optional communication speed between the minimum and maximum communication speeds of a multirate where a relative-delay-time-difference of a symbol of input optical wavelength.

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