Narrow optical filtering tolerance of 127-Gb/s DP-QPSK utilizing real-time DSP with 20 cascaded 50-GHz filters in the presence of 40, 200-ps/nm chromatic dispersion. - Suhas Bhandare; Zhenxing Wang; Kyu Kim; Mark Colyar; Heider Ereifej (OFC/NFOEC, 2013)