WALK-OFF EFFECT ON THE GENERATION OF ULTRASHORT PULSES FROM CW LIGHT USING CROSS-PHASE MODULATION IN OPTICAL FIBERS

We investigate the role of walk-off in the evolution of a weak cw wave in the anomalous-dispersion regime modulated by an intense picosecond pulse through cross-phase modulation. The cw wave can evolve into a short pulse whose duration and amplitude will depend on the degree of walk-off. When the walk-off length is shorter than necessary for short-pulse formation, the signal wave becomes amplitude modulated with a modulation depth of a few percent. In this case a frequency chirp exists in the signal wave, which can be used to generate short pulses on propagation through an appropriate dispersive element. © 1990 Optical Society of America.