Optical and nonlinear characterization of Er-doped SnO₂ thin films fabricated by thermal evaporation: potential for advanced optical device applications

The present work uses the thermal evaporation approach to create various Er-doped SnO₂ thin film compositions. We have conducted thorough optical, morphological, and nonlinear studies using various instrumentation approaches. Utilizing absorption spectra, the indirect and direct bandgaps (Eg) and absorption coefficient (α) are calculated. With different Er concentrations, the films’ transmission spectra had a visual transmittance range of 80 to 85%. With the aid of a femtosecond laser and the Z-scan technique, the third-order nonlinear optical behavior of Er-doped SnO₂ thin films has been examined. The open and close aperture approach is employed to determine the values of several parameters, including the nonlinear refractive index (n₂) along with the nonlinear absorption coefficient (β). The numeric values of n₂, β, and susceptibility χ⁽³⁾ were found to be in the order of ~ 10^–12 cm² /W, ~ 10^–5 cm/W,and ~ 10⁻⁵esu, respectively. Such nonlinear parameter values demonstrate the potential of thin films for use in optical device applications.