RECEIVER FOR OPTICAL COMMUNICATION SYSTEM AND METHOD FOR OPERATING THE SAME

PROBLEM TO BE SOLVED: To provide a receiver for optical communication system which is not affected by the drift of the transmission function of a filter. SOLUTION: This receiver is provided with a 1st periodic optical filter Rx1, a 2nd cyclic optical filter Rx2, a 1st photodetection unit PD1 and a 2nd photodetection unit PD2 connected installed after these filters. The reciproactive time of the 2nd filter Rx2 is shifted from the reciprocative time of the 1st cyclic optical filter Rx1 just by about 1/4 of the average optical wave cycle of received signal. The input to the filters Rx1 and Rx2 is connected through a beam splitter KOP to a communication system. The amplitude of output signals from two filters Rx1 and Rx2 is squared by two squarers Q1 and Q2 and added by an adder AD. As a result, a receiver R is hardly affected by the drift in the transmission function of the filter.