Adaptive CD estimation for coherent optical receivers based on timing error detection

An adaptive chromatic dispersion (CD) compensation algorithm based on Lee's timing error detector (TED) is proposed for coherent communication systems. By combining both the in-phase and quadrature component of the timing phase estimate parameter that is in Lee's TED, a CD estimation parameter insensitive to other transmission impairments can be generated. The proposed estimation method requires many fewer symbols compared with other methods based on blind linear CD search. In addition, the proposed technique is largely based on feed-forward timing phase recovery and requires very few additional resources from the hardware implementation point of view. Simulation results for polarization-division multiplexed quaternary phaseshift keying as well as 16-quadrature amplitude modulation systems using non-return-to-zero and Nyquist pulse in the presence of various channel distortions show that high CD estimation accuracies can be achieved.