The Study on Supercontinuum Generation of Femtosecond Pulse Propagating in Condensed Media

Starting from Nonlinear Schrodinger´s equation and using the Split-step Fourier Method, we studied the characters of the supercontinuum generation of femtosecond laser pulse propagating in condensed media; many physical factors are included such as the propagation distance, the input pulse peak power, diffraction effect, dispersion effect and the nonlinear effect etc. The results show that, when the femtosecond pulse propagated inside condensed media, the process of supercontinuum generation can be divided into two main stages: the pulse compressed stage, which induced by the self-focus and other third nonlinear effects of the material; and the pulse splited stage, which leaded by the self-phase modulate and the group velocity dispersion of the material. When the femtosecond pulse propagated inside the condensed media with high input peak power, the 3rd- order nonlinear effect of material induced pulse compressed and then the sub-pulses were produced, so that new frequency components were introduced. At the same time, we also studied the spectral distribution of the pulse at different spatial locations; there are new frequencies around the central frequency. At last, some experiments were done to demonstrate the supercontinuum generation.