Linear and Nonlinear Refractometric Study of Pb Doped Se-Te-Bi Chalcogenide Thin Films

The aim of this work is to investigate the linear and nonlinear refractometric study of Pb doped Se-Te-Bi chalcogenide thin films. Thin films of quaternary Se-Te-Bi-Pb chalcogenide glassy alloys prepared by melt quenching technique, are deposited on glass substrate using thermal evaporation method. The transmission spectra of quaternary chalcogenide thin films in the spectral range 400-2500 nm were obtained using a double beam UV-Vis-NIR spectrophotometer. The linear refractive index (n) is calculated using well known Swanepoel method with the help of transmission spectra and shows the normal dispersion behaviour. The linear refractive index (n) is found to increase with the incorporation of Pb content to the host Se-Te-Bi matrix. The nonlinear behaviour of refractive index is ascertained by using Boling model. The obtained value of nonlinear refractive index (n(2)) is found to be 6000-10000 times higher than pure silica which is advantageous for optical limiting devices, optical fibers etc.