Optical properties of laser ablated gallium lanthanum sulphide chalcogenide glass thin films prepared at different deposition laser energy densities

This paper describes the optical properties of GLS thin films deposited by laser ablation technique. These results complement the structural and compositional data on the same specimens reported in the preceding papers. A systematic investigation of the energy dependence of the refractive index, optical absorption edge, Urbach edge and optical gap has been carried out as a function of increasing deposition energy density. The optical absorption coefficient as a function of photon energy, deduced from transmission (T) and reflection (R) measurements, shows a very large shift of the edge towards lower energies relative to that of bulk glass with increasing deposition energy density. The optical gap, as determined by Taut extrapolation, and Urbach parameter have been determined as a function of deposition energy density. The changes in optical properties are correlated with the structural data

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