Accelerating chromatic dispersion estimation in coherent optical receivers

We present a fast and robust method for the estimation of residual chromatic dispersion (CD) in coherent optical receivers. The estimation method relies on the clock tone quality in the presence of polarization-mode dispersion (PMD) and CD. The robust estimation is accomplished using estimation cost functions covering a wide range of PMD, while the estimation time is reduced thanks to a rough scanning range and interpolating estimation results. Comparing to the published estimation algorithms, a coarse estimation using CD scanning step of 1 ns/nm combined with a trivial fine tuning (e.g. step 10ps/nm) shortens the estimation time several times with an estimation error less than 5 ps/nm.