Broadband second-harmonic generation in orientation-patterned GaAs

The efficient broadband quasi-phase matching (QPM) second-harmonic generation (SHG) is investigated in orientation-patterned (OP) GaAs. Based on the theory of broadband QPM SHG, the group-velocity (GV) matching wavelength, corresponding QPM crystal grating period and SHG bandwidth are obtained at room temperature(25 degrees C). The influence of temperature on broadband QPM SHG are studied. The broadband QPM SHG behavior with the fundamental wave centered at 7, 9.24, 10 and 13 (mu m) are discussed. For broadband QPM SHG, GV matching wavelength and corresponding QPM crystal grating period are 9.24 (mu m) and 219.28 (mu m), SHG bandwidth are 744 nm for the crystal length is10 mm at room temperature. The SHG bandwidth decreases with deviation from central wavelength increasing, when the crystal length is10 mm, the SHG bandwidth are 31 and 60 nm with the fundamental wave centered at 7 and 13 (mu m) at room temperature, respectively. The influence of temperature on GV matching wavelength and SHG bandwidth is little. The result can be used for broadband mid-infrared laser SHG with bandwidth several hundred or tens of nanometers.