Observation of self-steepening of optical pulses with possible shock formation

Near-resonant light pulses were steepened by passage through Rb vapor. The rise time changed from typically 4 nsec to less than 1 nsec, and complicated envelopes developed. The self-steepening, well described by adiabatic following, results from (i) an intensity-dependent pulse velocity, (ii) self-phase modulation combined with strong groupvelocity dispersion. Numerical integration gives quantitative agreement with observations and indicates shock formation on the leading edge. © 1973 The American Physical Society.