Photodoping with silver affects all the physical and chemical properties of the As-S chalcogenide films, particularly their electronic and Optical properties. In this article, Optical properties of As-S films photodoped with silver are investigated in some detail. Changes in the refractive index of up to 0.5 are detected in these glasses over the whole wavelength range from the visible up to the far-IR. Also, changes up to 0.6 eV in the Optical gap can be achieved. Although the introduction of Ag increases the absorption coefficient in the visible region, in the near IR and far IR part of the spectrum, a remains small.

Effects of low-intensity UV treatment on the Optical constants of red BS dye-doped polymethyl methacrylate (PMMA) film including refractive index, extinction coefficient, real and imaginary parts of dielectric constant, band gap energy, Urbach energy, and refractive index dispersion parameters are measured and calculated.Changes in Optical constants mainly occurred in the UV–VIS range. Red BS dye, which is used as a UV absorber impurity in PMMA films, generated another energy band gap which was increased by UV treatment. Although some of the Optical constants of PMMA are not changed noticeably by the treatment in this low range of UV radiation, our results confirm that polymeric changes such as chain scission and depolymerization can directly affect the Optical constants of PMMA.

The refractive index of poly(methyl methacrylate) (PMMA) thin films on glass substrates, prepared by spin coating method has been studied using a spectroscopic ellipsometry. Spectroscopic ellipsometry measurements of PMMA thin films were carried out at three angles of incidence, over the wavelength range of 400-700 nm. Optical Cauchy model was used to obtain thickness of the prepared films along with some Optical constants. Each PMMA thin film shows a characteristic dispersion relation, although they all behave similarly. Refractive indices were found to be in the range 1.49-1.53 with the maximum wavelength at 400 nm, and found to increase with increasing molecular weight of PMMA, and consequently causing an increase in film thickness. It was found that changing the molecular weight of PMMA and as a result the thickness of the films prepared made significant changes in both real (e1) and imaginary (e2) parts of the dielectric constant as a function of wavelength. The e1 and e2 peaks near 570 and 500 nm, respectively, were shifted towards lower energy upon increasing molecular weight. The refractive index variation and the appearance of surface roughness after UV illumination were evident. The roughness is modelled after fitting the spectroscopic ellipsometry data by using Bruggeman effective medium approximation assuming 50% PMMA and 50% voids. It was found that the UV illumination for one hour decreases the refractive index by 2 x 10-3. The refractive index changes upon UV illumination might be attributed to different factors namely: (i) microstructural defects; (ii) decomposition of PMMA molecules; (iii) carbon-oxygen polarization; and (iv) dipole-dipole intermolecular interactions.

Copper nitride films were prepared on glass by reactive direct current magnetron sputtering at various Ar/N2 contents at room temperature. Optical reflectance and transmittance spectra have been obtained in the range 200-2000 nm. The Optical properties of the deposited films are influenced by the N2 partial pressure significantly. The Optical transmittance of the films increases with increasing the nitrogen contents. Also by increasing the amount of nitrogen in working gas, the Optical absorption coefficient of Cu3N films was increased. The Optical band gap of the films is estimated by the absorption coefficients values at the absorption edge using Tauc's procedure. For deposited films both real (n) and imaginary (k) parts of the complex refractive index are calculated.