Chalcopyrite Crystals.

CdSiP$_{\mathrm{2}}$ (CSP) and CdGeP$_{\mathrm{2}}$ (CGP) are negative uniaxial II-IV-V$_{\mathrm{2}}$ chalcopyrite compound semiconductors. Optical rectification is demonstrated in CSP and CGP providing terahertz (THz) generation. These sources are compared to ZnGeP$_{\mathrm{2}}$ (ZGP)$^{\mathrm{[1]}}$ over a wavelength range of 1200 nm to 2320 nm at an average pump power 3.7 mW and emission strength is fitted to these two dependencies. During this analysis $\alpha $ (linear absorption coefficient), $\beta $ (two-photon absorption), and $\gamma $ (three-photon absorption) are taken into an account while comparing with the values of the ZGP and a conclusion is made of the properties of CSP and CGP. [1] J. D. Rowley\textit{ et al,} Optics Letters, Vol. 37, No. 5 (2012)