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Theoretical Analysis of Efficient Terahertz Difference Frequency Generation in Periodically-Inverted GaAs Crystals

This paper reports the analysis of efficient terahertz (THz) wave generation on the basis of quasi phase matching (QPM) difference frequency generation (DFG) in periodical GaAs by CO2 laser. The efficient second-order nonlinear susceptibility of GaAs was calculated by similar to the calculation it of uniaxial crystal. We calculated second-order nonlinear susceptibility for the incidence two pump lights with the same propagation directions. The result shown that, the incidence two pump lights with the perpendicular polarization directions and the same polarization directions were efficient to obtain high power conversion efficiency of THz wave.