Excitation wavelength dependences of terahertz emission from surfaces of InSb and InAs

The terahertz (THz) power radiated by the femtosecond laser excited semiconductor surfaces was measured by the Golay cell. Intrinsic InSb crystals as well as n- and p-type InAs were investigated by using three different wavelength, 780, 1030, 1550 nm, femtosecond lasers. It has been shown that p-type InAs crystal is the most efficient THz emitter for all three laser wavelengths with a nearly constant optical-to-THz power conversion efficiency of approximately 10^-6.