Specialty Optical Fibers Handbook

interchannel impairment, is usually the dominant nonlinearity in 10-Gbps DWDM

systems. Four-wave mixing (FWM) can be essentially eliminated as an impairment

between channels in 10-Gbps systems as long as the fiber dispersion across the band

is greater than approximately 2 ps/nm-km [5]. Self-phase modulation (SPM),

XPM, or FWM between temporally adjacent bits at the same wavelength (i.e.,

intra-channel nonlinearities) tend to dominate in 40-Gbps systems. The OSNR

improves linearly (on a decibel scale) as transmitted power increases; however, the

penalty due to nonlinear impairments increases with transmitted power. An optical

transmission system is often designed to operate in the sweet spot that maximizes

OSNR but avoids significant nonlinear distortions. ...