XPM and FWM in OFDM optical systems

Summary form only given. Cross-phase modulation (XPM) and four-wave mixing (FWM) are two of the most important sources of nonlinear crosstalk in multi-wavelength fiber-optic systems and their effects are generally proportional to signal optical power and inversely proportional to the channel spacing. In OFDM and OSCM systems, the channel spacing can be as narrow as a few Gigahertz, which is comparable to the data rate but the optical power per channel is also low. We assume that the aggregated total data rate is 100 Gbit/s, the total optical bandwidth is 1000 GHz (~8 nm), the total optical power is 10 mW after each optical amplifier and each wavelength channel has the same optical power and data rate. We use the Gaussian approximation for nonlinear crosstalk due to XPM and FWM and for evaluating their standard deviations normalized to the optical signal