Fast and robust blind chromatic dispersion estimation using auto-correlation of signal power waveform for digital coherent systems

We propose a chromatic dispersion (CD) estimation technique by using the auto-correlation of signal power waveform for DSP based coherent systems. For single-carrier polarization-division-multiplexed (PDM) systems assuming Gaussian pulse shapes, we analytically show that the auto-correlation of signal power waveform contains a peak whose location is indicative of the accumulated CD and is insensitive to amplified spontaneous emission (ASE) noise, laser frequency offset, laser phase noise and first-order polarization-mode dispersion (PMD) and applicable to single-carrier phase-shift keyed (PSK) and quadrature-amplitude modulation (QAM) systems. As a linear scan of a preset range of CD is not needed, the number of symbols of the proposed technique is dramatically reduced. Simulation results show that to estimate the link CD for 112 Gb/s PDM-QPSK and 224 Gb/s PDM-16-QAM systems, 8192 symbols are sufficient for NRZ/RZ pulse shapes and 32768 symbols are sufficient for root-raised-cosine pulse shapes with the roll-off factor as low as 0.1 with estimation error below 175 ps/nm and 400 ps/nm, respectively.