Patent ID: 8260154

Claim:
A digital equalization apparatus for a coherent optical receiver, the digital equalization apparatus comprising: a photoconverter to convert a received optical signal into a digital signal; and a signal processor to compensate for chromatic dispersion and polarization dispersion in the optical signal by processing the converted digital signal and to perform symbol synchronization in a digital manner by use of a clock different from a sampling clock of the photoconverter, wherein the signal processor comprises: a chromatic dispersion compensation unit to receive an output of the photoconverter and compensate for the chromatic dispersion; a digital symbol synchronization unit to receive an output of the chromatic dispersion compensation unit and perform the symbol synchronization; a polarization compensation unit to receive an output of the digital symbol synchronization unit and compensate for the polarization impairment; and a frequency and phase compensation unit to receive an output of the polarization compensation unit and compensate for frequency difference and phase noise between a local oscillation signal of the photoconverter and the optical signal, wherein the digital symbol synchronization unit comprises: an interpolation unit to perform interpolation on the output signal of the chromatic dispersion unit; and a clock determination unit to determine an operation clock for the interpolation unit by detecting timing error of the interpolation unit and using the detected timing error.