Patent ID: 7174098

Claim:
An apparatus for monitoring information on the waveform of an optical signal, comprising: a photocoupler which introduces an input optical signal into a branch path; extraction means for extracting, from the optical signal introduced into the branch path by said optical coupler, a clock signal synchronized with the optical signal; a optical gate which controls timing of opening and closing of a gate on the basis of the clock signal extracted by said extraction means to control transmission and non-transmission of the optical signal introduced into the branch path by said photocoupler; adjustment means for adjusting the phase difference from the optical signal of the clock signal extracted by said extraction means; detection means for detecting the intensity of light of the optical signal transmitted through said optical gate on the basis of the clock signal phase-difference-adjusted by said adjustment means; and waveform information extraction means for extracting information on the waveform of the optical signal on the basis of the light intensity detected by said detection means.