Cross-phase modulation and multiwavelength adiabatic solitons

In an experimental demonstration of four-channel, wavelength-division-multiplexed repeaterless transmission over 235 km, adiabatic soliton propagation allows for precise spectral characterization of cross-phase modulation effects during initial soliton collisions. Theoretical predictions of the spectral shifts that occur are verified for ultrashort solitons. The relationship between the frequency shift and the initial pulse separation is confirmed by measurement of the bit-error ratio as the pulse spacing is varied at the fiber input. Adiabatic expansion of narrow solitons may help to alleviate the channel restrictions that are required for prevention of soliton collisions at the fiber input.