Theoretical analysis of terahertz generation in periodically inverted nonlinear crystals based on cascaded difference frequency generation process

The characteristics of terahertz (THz) generation based on cascaded difference frequency generation (DFG) process in periodically inverted gallium arsenide ( GaAs ) and gallium phosphide ( GaP ) is calculated from coupled wave equations, in which the output enhancement factors are 5.4 and 3.9 in the two crystals, respectively, compared with DFG without cascading. The optimal interaction length, influence of crystal absorption, wave vector mismatch and pump intensity are analyzed. A short discussion on wavelength tuning is also given. The calculated optimal operating parameters and conclusions can provide good directions for the experimental design.