Inter-channel nonlinear crosstalk in analog phase-modulated wavelength-division-multiplexed systems.

We investigate the inter-channel nonlinear optical crosstalk in analog phase-modulated (PM) wavelength-division-multiplexed systems. The optical transmitters of the PM system produce constant optical intensity at the output. However, the chromatic dispersion of fiber induces amplitude fluctuations which in turn give rise to fiber nonlinearities to other channels through stimulated Raman scattering (SRS) and optical Kerr effect. We present theoretical analysis on SRS and cross-phase modulation (XPM) for PM systems and compare it with two-channel experiment and numerical simulation. The results show that PM systems significantly suppress SRS and XPM, compared to intensity-modulated systems. Our experiment and simulation results confirm that the total nonlinear crosstalk in the analog PM WDM system is reduced up to 15 dB.
((c) 2008 Optical Society of America)