Crosstalk Mitigation in Multichannel Optical Parametric Sampling via Raman Amplification

We propose to use backward Raman amplification to mitigate the crosstalk in multichannel optical parametric sampling. The performances of multichannel sampling based on four-wave mixing (FWM) have been experimentally compared with different Raman pump powers. Optical crosstalk is suppressed by lowering the input signal power so that the depletion of the parametric pump and higher order FWM products are reduced. Meanwhile, Raman amplification compensates the parametric pump power and improves the conversion efficiency, thus maintaining the output idler power. A 12.2- and 13.6-dB reduction of crosstalk-induced frequency components has been achieved in two output channels. We also analyze bandwidth broadening resulting from the self-phase modulation of the pulsed parametric pump for the two cases when it is amplified by an erbium-doped fiber amplifier and by the Raman pump.