DIFFERENCE OF SPECTRAL SUPERBROADENING BEHAVIOR IN KERR-TYPE AND NON-KERR-TYPE LIQUIDS PUMPED WITH ULTRASHORT LASER-PULSES

The spectral superbroadening behavior of forward coherent radiation from a lo-cm-long liquid-filled cell is investigated by using an ultrashort (approximately 0.5 ps) and intense (approximately 10 GW/cm2) laser pulse as the pump source. Five different transparent liquids (heavy water, water, carbon tetrachloride, benzene, and carbon disulfide) have been studied with a special experimental design that can distinguish the predominant contributions from the various possible mechanisms. Under the same pump condition, a very wide and symmetrical superbroadening (continuum) is observed on both the Stokes and the anti-Stokes side of the pump line for non-Kerr-type liquids such as heavy water and water, whereas only a red-shifted spectral broadening can be observed on the Stokes side for Kerr-type liquids such as carbon disulfide and benzene. For an explanation of the latter behavior, the dominant contributions from stimulated Rayleigh-Kerr and Raman-Kerr scattering are proposed.