SPECTRAL SUPERBROADENING OF FEMTOSECOND LASER-PULSES

The spectral superbroadening of femtosecond pulses in water, heavy wat er, ethanol, and fused silica is studied under strong focusing conditi ons. Efficient transient stimulated Raman scattering, impulsive stimul ated Raman scattering, longitudinally phase-matched parametric four-ph oton interaction, and cascading light up-conversion and down-conversio n are responsible for the spectral superbroadening. Self-phase modulat ion and cross-phase modulation broaden the laser and stimulated Raman lines.