An effect of reversible photostructural transformations in sulfide-selenide thin films was studied in the paper. In photostructural transformations, induced by strongly absorbed light, practically all the properties of               1As₂S₃ · 1As₂Se₃ are changed reversibly. In the process of photostructural transformations especially strongly change optical properties: absorption coefficient and refractive index (photodarkening or photobleaching and photorefraction effects), density (photoexpansion or photocompression effect), and the rate of dissolution in chemical solvents (photodissolution effect). The basis of the reversible photostructural transformations effect is the photo‑thermo‑induced reorganization of interatomic bonds, initiated by the photo-excitation of the so-called lone-pair electrons.

     Novel micro-lens arrays produced from sulfide-selenide thin films are presented. Film thicknesses were in the range of 2.5 – 3.0 µm. Sulfide-selenide micro-lenses are characterized by high optical quality obtained by application of grey scale and gap micro-lithography, and thermal reflow method for their fabrication. This technology, used for the formation of sulfide-selenide micro-lens arrays, is discussed.

     A new design of active micro-optical components is based on the use of 3D shaped sulfide-selenide micro-lenses immersed in a nematic liquid crystal, E 90, to form an electrically tunable focal length. The fabrication technology of new active micro-lens arrays has been developed. The focal length of the active micro-lenses is changed by varying the applied voltage.

Acknowledgment. The work was supported by the Grant of the Ministry of Science and Technology State of Israel (Israel - Ukraine Foundation) "Development of advanced photosensitive materials for alignment of liquid crystals and their application in adaptive micro-lens array technology".  

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