SUBPICOSECOND STIMULATED RAMAN-SCATTERING IN HIGH-PRESSURE HYDROGEN

We studied the effect of self-phase modulation and self-focusing on tr ansient stimulated Raman scattering in high-pressure hydrogen by using high-energy, subpicosecond laser pulses. Adding argon to the hydrogen emphasizes the effect of self-phase modulation on stimulated Raman sc attering by increasing the former effect without affecting the latter. The behavior of the observed stimulated Raman scattering falls into t hree regimes depending on input energy: normal stimulated Raman scatte ring at low energies, suppression by self-phase modulation at medium e nergies, and a recovery at high energies because strong self-focusing limits self-phase modulation.