Thin amorphous As-S films were prepared using pulsed laser deposition. Raman scattering spectroscopy, variable angle spectroscopic ellipsometry, and optical transmittance spectra revealed irreversible photostructural effects, significant photoinduced changes of refractive index, and optical band gap energy in the films. Observed effects are discussed in terms of structural transformations of basic structural units. (C) 2008 Elsevier B.V. All rights reserved.