Optical fiber nonlinear effects in lightwave communication systems

Advances in optical amplifier technology have reshaped the lightwave communications landscape. Erbium-doped fiber amplifiers have enabled systems engineers to begin exploiting the enormous transmission capacity of single-mode fibers. However, implementation of optical amplifiers magnify the effects of optical nonlinearities in the transmission fibers. These nonlinearities will limit the information capacity of lightwave communications. The nonlinearities can be separated into two broad classes. Stimulated scattering processes, such as Brillouin and Raman, cause wavelength conversion of signals. This gives rise to unwanted noise, crosstalk, and power depletion. The nonlinear refractive index of silica is the source of such effects as self-phase and cross-phase modulation which produce spectral broadening, and four-photon mixing which mixes signals in wavelength multiplexed systems. This talk will describe the various optical nonlinearities and discuss the limits imposed by these nonlinearities on the information capacity of lightwave communication systems. Methods for reducing the systems impact of nonlinearities will also be presented