Chromatic Dispersion Estimation for Single-Carrier Coherent Optical Communications

We propose and demonstrate a blind chromatic dispersion (CD) estimation technique for single-carrier coherent optical communication systems. We show that the peak-to-average-power ratio (PAPR) of a signal is a good indicator of the amount of CD the signal experiences and the minimum PAPR typically corresponds to zero accumulated CD. By scanning CD values of a CD compensator in a coherent receiver and monitoring the PAPR after the CD compensator, CD can be estimated accurately. We experimentally demonstrate this technique in a non-dispersion-managed optical transmission system with mixed 130-Gb/s polarization-division-multiplexed quadrature-phase-shift-keying (PDM-QPSK) and 260-Gb/s PDM 16-ary quadrature-amplitude-modulation (PDM-16QAM) channels and show that the technique works well for both PDM-QPSK and PDM-16QAM even with Nyquist pulse shaping.