Pilot-based XPM nonlinearity compensator for CO-OFDM systems.

We experimentally verify that pilot-based nonlinearity compensation is effective for mitigating XPM in CO-OFDM systems, if SPM is compensated first. A 6-dB increase in the nonlinear limit was produced by pilot-based XPM compensation after a single-step SPM compensator in a 400-km link with periodic dispersion compensation. In addition, we use numerical simulations to show that the required bandwidth of the guard-band around the pilot is almost independent of the bandwidth of the data-carrying sidebands.

Fiber nonlinearity precompensation for long-haul links using direct-detection optical OFDM.

The use of nonlinearity precompensation in direct-detection optical orthogonal frequency division multiplexed links is investigated by simulation. Because of the presence of a strong optical carrier its performance is poorer than for coherent systems: with compensation the signal quality is found to vary almost periodically across the signal band. We propose and explain the operation of two optical, one electrical and one computational method of removing this periodic variation.