Self-steepening and self-compression of ultrashort optical pulses in a defocusing CdS crystal

Some consequences of the nonlinear propagation of a visible optical pulse in CdS, in a regime where the nonlinear index of refraction is negative, have been exhibited using a time-of-flight technique in the femtosecond regime. The self-steepening of the optical pulse is evidenced directly in the time domain. Self-shortening of the pulse occurs on a distance as short as 130 mu m opening the way of direct optical compression inside semiconductor lasers. Tunable optical soliton propagation is predicted which could be useful for multiplexing purposes.