COHERENT OPTICAL RECEIVER, AND INTER-CHANNEL SKEW DETECTION DEVICE AND DETECTION METHOD IN COHERENT OPTICAL RECEIVER

摘要

Because sufficient demodulation cannot be performed and reception performance deteriorates when a skew occurs between channels in a coherent optical receiver, this coherent optical receiver has a localized light source, a 90° hybrid circuit, a photoelectric converter, an analog-digital converter, and a digital signal processor. The 90° hybrid circuit outputs a plurality of optical signals separated into a plurality of signal components by causing a multiplexed signal light to interfere with a localized light from the localized light source, the photoelectric converter detects the optical signal and outputs a detection electrical signal, and the analog-digital converter quantizes the detection electrical signal and outputs a quantized signal. The digital signal processor comprises a skew compensator for compensating for the differential delay in transmission between the plurality of signal components and a FFT calculator for high-speed Fourier transformation processing of the quantized signal, and the differential delay in transmission is calculated on the basis of a plurality of peak values with one peak value as the center in the results of the high-speed Fourier transformation processing.