OPTICAL RECEIVER

摘要

PURPOSE: To improve the saturation level of the signal to noise ratio (SNR) based on the circuit noise of the optical receiver by reducing the fluctuation of an optical current value at an O/E module and keeping the optical current value at a large value as much as possible concerning the optical receiver composed of an optical preamplifier and the O/E module. CONSTITUTION: Concerning the optical receiver composed of an optical preamplifier 1 for amplifying an optical signal and an O/E module 2 equipped with a light receiving element 3 for converting the optical signal output of the optical preamplifier 1 to an electric signal and outputting it, an optical current monitor circuit 4 is provided to detect the average value of the optical current of the light receiving element 3 and a control circuit 5 is provided to control the optical output of the optical preamplifier 1 so that the optical current detected value of the optical current monitor circuit 4 can be fixed. Thus, the optical input from the optical preamplifier 1 to the light receiving element 3 is kept at the large value as much as possible and controlled so as to reduce its fluctuation.