High-efficiency THz generation in optically contacted GaAs with near-Brewster angle pumping

摘要

[[abstract]]High-efficiency THz generation in quasi-phase matched (QPM) optically contacted GaAs (OC-GaAs) with near-Brewster angle pumping is studied numerically. The effective nonlinear coefficients d(eff) for different incident angles and polarization directions are investigated. Compared with the normal incidence case, reflection loss of the pump energy at OC-GaAs interfaces can be reduced by propagating the pump at a near-Brewster angle (66.92 degrees). The effect of the air-gap spacings between adjacent OC-GaAs layers to the number of optimal QPM periods and the efficiency of THz generation are calculated. In our study, the number of optimal QPM periods of OC-GaAs is increased significantly from 12 in the normal incidence configuration to 25 in the near-Brewster angle pumped configuration, while the efficiency of THz generation is enhanced by more than 16 times.