Optical Mitigation of Inter-Channel Crosstalk for Multiple Spectrally Overlapped 40-Gbit/s QPSK WDM Channels using Nonlinear Wave Mixing

Using an all-optical method and without multi-channel detection, the inter-channel interferences of overlapped WDM data channels are mitigated simultaneously. We experimentally demonstrate performance improvement for 20-Gbaud QPSK overlapped channels under different channel spacing. The scheme results in near 4dB OSNR gain for QPSK data channels at a BER of 10-3.