An optical reception circuit and an identification level controlling
method for an optical reception circuit are disclosed wherein reception
sensitivity degradation arising from transmission waveform degradation by
chromatic dispersion can be suppressed. The optical reception circuit
includes a photoelectric converter for converting reception light into an
electric signal, a pre-amplifying unit for amplifying the electric
signal, a main amplifier for amplifying an output of the pre-amplifying
unit, a monitor for monitoring the output of the pre-amplifying unit, and
a controller for controlling an identification level in the main
amplifier based on an output of the monitor. The monitor includes a
limiter amplifier for amplifying the output of the pre-amplifying unit,
and an average value detector for detecting a time average value of an
output amplitude of the limiter amplifier.