Transmitter quadrature imbalance compensation at a coherent optical receiver

摘要

It is disclosed a an apparatus for compensating transmitter quadrature imbalances over an optical signal received at an optical coherent receiver of a node of an optical communication network. The optical signal comprises information symbols and pilot symbols. The receiver is configured to store a sequence of reference pilot symbols. The apparatus comprises an absolute phase estimating circuit configured to estimate a phase error between a received pilot symbol and a corresponding reference pilot symbol; a phase correcting module configured to remove the phase error from the received pilot symbol and a number of received information symbols associated with the received pilot symbol; a quadrature imbalance detection circuit configured to estimate the transmitter quadrature imbalances on the basis of at least the phase-corrected pilot symbol; and a quadrature imbalance compensation circuit configured to compensate the estimated transmission quadrature imbalances over the number of phase-corrected information symbols.