Determining the refractive index and average thickness of AsSe semiconducting glass films from wavelength measurements only

Abstract

The dispersive refractive index n(λ) and thickness d of chalcogenide glass thin films are usually calculated from measurements of both optical transmission and wavelength values. Many factors can influence the transmission values, leading to large errors in the values obtained for n(λ) and d. Anovel optical method is used to derive n(λ) and d for AsSe semiconducting glass thin films deposited by thermal evaporation in the spectral region where k(2) « n(2), using only wavelength values. This entails obtaining two transmission spectra: one at normal incidence and another at oblique incidence. The procedure yields values for the refractive index and average thickness of thermally evaporated chalcogenide films to an accuracy better than 3%.

Characterising refractive index dispersion in chalcogenide glasses

“…According to [14], the Cauchy model does not encompass the entire glass transparent window and so in the present work the Cauchy dispersion equation used in [20] was changed to a two-term Sellmeier dispersion equation to extend the potential use of the method for determining the optical properties of chalcogenide thin film in the MIR region. The two methods gave consistent refractive index results from the experimental data of [21] over the 600-2000 nm wavelength region.…”

“…This entails measuring two transmission spectra, one at normal incidence and another at oblique incidence. This method was used by Corrales et al to measure the refractive index of an As40Se60 thin film of approximate thickness in 600-2000 nm wavelength region [21] and the method yielded values for refractive index and average thin film thickness to an accuracy of better than 3%.…”

Determining the refractive index dispersion and thickness of hot-pressed chalcogenide thin films from an improved Swanepoel method

“…This entails measuring two transmission spectra, one at normal incidence and another at oblique incidence. The Swanepoel method was used by Corrales et al (1995) to measure the refractive index of an As 2 Se 3 thin film in the 600-2000 nm wavelength region and the method yielded values for refractive index and average thin film thickness to an accuracy of better than 3%. In this paper, an improved Swanepoel method, based on Swanepoel (1985), but modified by the introduction of a Sellmeier dispersion equation in order improve the applicability of the method to chalcogenide glasses at MIR wavelengths, is introduced.…”

Terahertz-induced Kerr effect in amorphous chalcogenide glasses

“…The slightly higher As 2 Se 3 refractive index can be explained by the higher density of As 2 Se 3 (4.75 g/cm 3 ) compared to As 2 S 3 (3.42 g/cm 3 ). The group indices for the 800-nm optical probe beam are 2.76 24 and 3.65 25 for As 2 S 3 and As 2 Se 3 , respectively. The resulting velocity mismatch between the optical probe beam and the THz pulse may result in smearing of the recorded Kerr signals, and consequently a slight underestimation of the extracted nonlinear coefficient.…”