Optimization of the nonlinear regime of self-compression at femtosecond laser pulses in silica and air

Abstract

In the present work it is demonstrated two efficient methods of self-compression of femtosecond pulses based on suitable selection of optical elements, parameters of the medium and laser radiation. The basic idea is that the phase modulated pulses more efficiently can be compressed trough nonlinear mechanisms. The first method can be applied for mediums with significant dispersion like fused silica, where the sign of the dispersion of the group velocity is important. We show that the combination of focusing by optical lens and a balance between anomalous dispersion and nonlinearity lead to significant compression from 100fs to~20-30fs of optical pulse. The second method for self-compression is by using only one optical diffraction grating to obtain broadband pulses and the following self-compression in nonlinear regime. In the second case in addition is observed generation of X wave.