Abstract-Theoretical Evaluation of Terahertz Sources Generating From Infrared Nonlinear Optical Materials SnGa4Q7 (Q = S , Se)

http://onlinelibrary.wiley.com/doi/10.1002/cphc.201601128/abstract

We have theoretically evaluated the integrate knowledge, which contribute to conversion efficiency, including the phonon, photon and electron properties of infrared nonlinear optical materials SnGa4Q7 (Q = S, Se) being as terahertz (THz) sources. Specially, we have developed a new formula to calculate susceptibility of difference frequency generation (DFG) optical process. By the characteristics of materials-self properties in the THz region, we find that a larger nonlinear susceptibility or a large figure of merit will result in a large efficiency of THz source by the comparisons between the findings of SnGa4Se7 and SnGa4S7 under the same experimental conditions, and the THz absorption will reduce the efficiency of THz source for the two materials of SnGa4Q7 (Q = S, Se). The efficiency of THz source also depends on the experimental conditions. A large crystal size, strong pump intensity and small THz wavelength will gain large efficiency of THz source based on DFG process. The efficiency is a comprehensive index to evaluate the THz source based on DFG process.