Fractional Fourier Transformation-Based Blind Chromatic Dispersion Estimation for Coherent Optical Communications

In this paper, we propose and demonstrate a blind chromatic dispersion (CD) estimation method based on fractional Fourier transformation (FrFT). Through numerical simulations, the proposed CD estimation method is shown to be robust against the amplified spontaneous emission noise and nonlinear interference. Only 2048 samples are required for reliable CD estimation for single-carrier 28 GBd DP-QPSK or 32 GBd DP-16QAM signals, and the standard deviation can be as low as 98.9 and 103.6 ps/nm, respectively. The feasibility of the proposed CD estimation method has been experimentally verified using 28 GBd DP-QPSK and 14 GBd DP-16QAM signals over various transmission distances with CD ranges of 46 332–77 220 ps/nm and 5148–51 480 ps/nm, respectively. Compared with some other CD estimation methods, the method based on FrFT has advantages in the aspects of less computation complexity and robustness to transmission impairments.