Influence of intermodal dispersion on the switching of solitons at different wavelengths in twin-core fiber couplers

In dual-core fibers the variation of the coupling coefficient with frequenc y leads to intermodal dispersion that perturbs the switching of ultrashort pulses. Using a new version of the split-step Fourier method based on a mod el that includes intermodal dispersion, we show that this effect cannot be neglected when the switching of picosecond solitons at different wavelength s in half-beat twin-core fiber couplers is analyzed, although picosecond so litons at the central wavelength are not significantly affected. We also sh ow that to study the switching of wavelength-division-multiplexed solitons one should always take into account the effect of intermodal dispersion. (C ) 1999 Optical Society of America [S0740-3224(99)00508-1].