Broadband terahertz pulse emission from ZnGeP_2
  Optical rectification is demonstrated in (110)-cut ZnGeP_2 (ZGP) providing broadband terahertz (THz) generation. The source is compared to both GaP and GaAs over a wavelength range of 1150 nm to 1600 nm and peak intensity range of 0.5 GW/cm^2 to 40 GW/cm^2. ZGP peak-to-peak field amplitude is larger than in the other materials due to either lower nonlinear absorption or larger second order nonlinearity. This material is well suited for broadband THz generation across a wide range of infrared excitation wavelengths. 
J. D. Rowley, J. K. Pierce, A. T. Brant, L. E. Halliburton, N. C.   Giles, P. G. Schunemann, and A. D. Bristow
cond-mat.mtrl-sci