Stimulated relaxational transformations in amorphous chalcogenide films

Irreversible changes of refractive index of as-deposited As x S 1-x amorphous films in course of physical ageing is studied using a prism-coupling technique. These changes result from an initiating effect of an optical mode in the film waveguide. It is shown that amorphous chalcogenide films can undergo structural and "mechanical" relaxational transformations triggered by sub-bandgap light irradiation. An approach based on floppy modes is proposed to understand the response and irreversible relaxation changes of structural, mechanical and optical properties of nanoinhomogeneous amorphous chalcogenides.