Interference of ordinary and extraordinary waves in AgAsS2 crystals

The anisotropy of the near-bandgap absorption is investigated in AgAsS2 crystals. The refraction indices, n‖ and n⊥ respectively for the E‖c and E⊥c polarizations as well as the spectral dependence of the refraction indices difference, Δn=n‖-n⊥ are determined from the interference spectra of AgAsS2 crystals. A transmission band with four maxima is observed in the transmission spectra of crystals placed between crossed polarizers. The optical parameters n, k, ε1, and ε2 for the E‖c and E⊥c polarizations are calculated from the reflection spectra by using the Kramers-Kronig relations.