Linear and nonlinear optical studies of indium selenide thin films prepared by thermal evaporation technique

The manuscript concerns linear and nonlinear optical studies of thin indium selenide films are
prepared using thermal evaporation technique, which is intensively researched due to its specific
characteristics. In the wavelength range, 300–2500 nm, the transmission and reflection spectrum
were taken using the VIS-NIR spectrophotometer. For processed films, the nonlinear optical parameters viz. nonlinear refractive index (n2) and third order nonlinear susceptibilities χ 3have
been tested by numerical calculation. The optical band gaps obtained from Tauc’s relationship for
direct and indirect transitions are within the scope of 3.6 − 1.9 eV and 1.55–1.1 eV, respectively,
and the band gap expanded with film thickness decreases.