Self-Trapping with Picosecond Pulses and "Rocking" of Molecules

Abstract
We report a study of the spectral properties of self-trapped filaments of light with picosecond excitation. The clean spectra obtained allow the measurement of the relaxation time of the nonlinear refractive index induced by the field; it is a few tenths of a picosecond for many liquids. We suggest that "rocking" of molecules in the field of neighboring ones is the main mechanism for trapping in our case.