Blind Chromatic Dispersion Estimation Using Fractional Fourier Transformation in Coherent Optical Communications

In this paper, we propose and demonstrate a blind chromatic dispersion (CD) estimation method based on fractional Fourier transformation (FrFT). When FrFT acts on linear frequency modulated (LFM) signal with energy convergence, it is compared to fiber chromatic dispersion signal, and the best order can be obtained by scanning or search method. Through numerical simulations, reliable CD estimation is demonstrated for 28 GBaud PM-QPSK and PM-16QAM signals with a range of (-70,45) ps/nm. The average estimation error of CD estimation is 0.15% and 0.5% when the transmission distance over 100km~2000km standard single mode fiber (SSMF).