Linear and nonlinear optical properties of Ternary and quaternary chalcogenide thin films

Abstract

Chalogenide glasses, with favorable properties like high linear and nonlinear refractive index, good transmittance in the infrared region, low phonon energy and photosensitivity make these glasses a potential candidate in lasers, amplifiers and high brightness sources for remote sensing applications. newlineThe present work deals with the linear and nonlinear optical properties of ternary (Se-Te-Bi) and quaternary (Se-Te-Bi-Sn) chalcogenide thin films. In this thesis we have studied following chalcogenide glass systems. newlineI. Se85-xTe15Bix (0 and#8804; x and#8804; 5) newlineII.Se84-xTe15Bi1.0Snx (0 and#8804; x and#8804; 8) newlineThe bulk samples were prepared by using well known melt quenching technique. The thin films of bulk samples were deposited on glass substrate using thermal evaporation method. The amorphous nature of bulk samples and their corresponding thin films has been confirmed by using X-ray diffraction technique. The optical properties are determined using transmission and reflection spectra in the spectral range 400-2500 nm obtained from a double beam UV-Vis-NIR spectrophotometer. The linear refractive index and extinction coefficient has been evaluated using Swanepoel method. Optical band gap (Eg)has been determined using Tauc relation. The nonlinear optical parameters viz; nonlinear refractive index (n2), two photon absorption coefficient (and#946;2), third order nonlinear optical susceptibility (and#967;(3))has been determined using different theoretical models. The values of different nonlinear optical parameters obtained theoretically are further verified experimentally, using Z-scan technique. newline