A modified method to simulate the dispersion properties of infrared nonlinear optical crystals

This paper presents a modified method to study the dispersion properties of infrared nonlinear optical crystals, which takes advantage of the first principles calculations and oscillator model. The phonon effects play an important role in the dispersion properties, and obvious discrepancies between calculated and experimental results are found due to the lack of such effects in first principles optical property calculations. In order to compensate for such deficiency, the oscillator model was introduced. Phonon oscillator terms are added to the calculated dispersion equations, and the phonon oscillator coefficients can be obtained from first principles infrared dielectric property calculations. With the modified method, the simulated dispersion curves of GaAs, CdSiP2, AgGaS2, and ZnGeP2 crystals show excellent agreement with the experimental results. (C) 2015 AIP Publishing LLC.