Variable angle spectroscopic ellipsometry was carried out using an RC2 ellipsometer (JA Woollam). Reflection measurements were collected from 50-80° at 5° increments for wavelengths 200-2500 nm. Optical dispersion data analysis of the raw ellipsometry data was performed using CompleteEASE v6.55 (JA Woollam). An Agilent Cary 5000 UV-VIS-NIR spectrometer was used to collect the transmission intensity of the crystal at normal incidence from 200-2500 nm.