Optical properties of amorphous As 45 S 15 Se 40 thin films

*The experimental investigations of the influence of the light irradiation on the optical parameters of one of highest sensitive chalcogenide glass [(As40S60)0.5:(As40Se60)0.5]0.5:(As50Se50)1.0 was investigated. For the amorphous As45S15Se40 thin films, prepared by „flash” thermal evaporation, from the transmission spectra the value of the refractive index n was found n=2.921 at λ=650 nm, and the optical band gap Eg was determined from the Tauc plot Eg=1.929 eV. The kinetics of photodarkening in amorphous As45S15Se40 thin films is described by stretch exponential function and the effect at illumination with laser beam λ=540 nm is more pronounced that in amorphous As2S3 and As2Se3 films. The maximum of the diffraction efficiency η of the holografical gratings recorded during the exposure of laser beam at λ=540 nm is reached at about t=250 s.