Resonances in Cross-Phase Modulation Impairment in Wavelength-Division-Multiplexed Lightwave Transmission

Cross-phase modulation impairment resonances occur in wavelength-division-multiplexed lightwave systems when channels are spaced such that an integral number of bit walk-through per amplifier span occurs. We have observed these resonances in transmission through 624 km standard single-mode fiber with equal amplifier span lengths of 40, 80, or 120 km. Q measurements of a 2.5-Gb/s, five-channel system over 8 x 80 km with +7 dBm/channel predict on-resonance bit error rates that are several orders of magnitude higher than off-resonance bit error rates.