Generation of terahertz radiation with a specified spectral profile from a mosaic combined organic crystal

We present a method for the generation of terahertz (THz) pulses with a high optical-to-THz conversion efficiency and a smooth spectrum. The method is based on the optical rectification of near-infrared femtosecond laser pulses with a wavelength of 1240 nm in a mosaic combined crystal, consisting of two pieces of nonlinear organic crystals, OH1 and DSTMS. The mosaic combined crystal produces a relatively smooth spectrum in the 0.3-4.5 THz range with no pronounced absorption dips and with a maximum in a spectral amplitude at about 2 THz. The peak field strength is 9.6 MV/cm for an effective crystal diameter of 4.3 mm.