Patent ID: 8195053

Claim:
An optical signal processing device, comprising: a waveform width widening unit configured to widen a waveform width of an optical signal; an optical limiter circuit, to which the optical signal the waveform width of which is widened is input, configured to suppress an intensity of the optical signal in a region where an input intensity and an output intensity are not proportional; and an optical circuit, wherein the waveform width widening unit is further configured to adjust an ON level time period and a zero level time period by extending a time period in which the optical signal is at the ON level and by shortening the time period in which the optical signal is at the zero level, the optical limiter circuit is further configured to suppress the noise on the ON level of the optical signal output from the waveform width widening unit, and the optical circuit is configured to change the ratio of the ON level time period and the zero level time period of an optical signal output from the optical limiter circuit back into an original ratio of the ON level time period and the zero level time period of the optical signal.