Method of measuring frequency response of optical coherent receiver

Abstract

A technique for measuring an optical coherent receiver is disclosed, where the optical coherent receiver recovers a data by an interference between signal light and local light. The technique includes steps of (i) equalizing optical lengths of the signal light and the local light from the optical source, respectively, and (ii) during a scan of the frequency, maximizing an output of the optical coherent receiver by the feedback control from an output of the optical coherent receive to the phase of the local light. The technique has a feature that, when the feedback control set a delay/lead in the phase of the local light to be 2Vπ−Δ, the delay/lead of the phase of the local light is decreased/increased by 2Vπ, where 2Vπ corresponds to one period of the wavelength of the local light.