Crosstalk and power penalty due to fiber four-wave mixing in multichannel transmissions

The influence of fiber four-wave mixing on multichannel transmissions is investigated. We present strict and approximate theoretical treatments for evaluating power penalty with intensity-modulated/direct-detection (IM/DD) and FSK/direct detection. A comparison of calculations shows that both methods yield the same result in the small penalty region. Using these treatments, power penalty and allowable fiber input power are derived for various system conditions. It is shown that the power penalty is not uniquely determined by the crosstalk level for CW lights, depending on the demodulation scheme and channel spacing, especially in the zero-dispersion wavelength region