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

Tolerance of 127-Gb/s DP-QPSK signal with real-time DSP is experimentally investigated. The results show high tolerance to narrow optical filtering with large CD and center frequency offsets making this system very attractive for Metro links.