2D simulation of generation of difference-frequency radiation by few-cycle laser pulse in thin crystal of GaAs

We present the results of theoretical study of generation of difference frequency radiation in interaction of few-cycle laser pulse with a GaAs thin crystal. 2D numerical time-integration of system of nonlinear Maxwell equations for the TE y mode has been performed by the finite-difference method. We consider the interaction of linearly-polarized pulse having the central wavelength of 1.98 μm, duration of 17.16 fs and the electric field amplitude E x 0,max = 100 MV/m, propagating along the normal to the 〈110〉 plane in the 14.74 μm-thickness GaAs crystal. The beam waist of initial linearly polarized pulse varies from 5.94 μm to 9.9 μm. The process of generation of difference frequency radiation (DFR) pulses arising at the output of nonlinear crystal via spectral filtration of formed supercontinuum is studied. The dependence of difference frequency generation efficiency on the beam waist is examined.