CANCELLATION OF STIMULATED-RAMAN-SCATTERING CROSS-TALK IN WAVELENGTH-DIVISION-MULTIPLEXED OPTICAL COMMUNICATION-SYSTEMS BY SERIES OR PARALLEL TECHNIQUES

We compare techniques using two fibers connected either in series or i n parallel for cancelling cross talk that is due to stimulated Raman s cattering in wavelength-division-multiplexed systems. Theory shows tha t such cross talk can be completely eliminated by a series arrangement in lossy dispersionless fibers by means of midway amplification and s pectral inversion. In dispersive fibers, cross-talk reduction of the o rder of the Raman gain G can be obtained by adding dispersion compensa tion and alternating dispersion. Alternatively, a similar cross-talk r eduction can be obtained by use of parallel transmission of signals on different sets of wavelengths and differential detection; in the pres ence of dispersion, the dispersion for the different sets of wavelengt hs must be opposite. The parallel approach appears to be more practica l. (C) 1998 Optical Society of America.