Infrared microlenses and gratings of chalcogenide: confined self-organization in solution processed thin liquid films

Abstract

This work demonstrates the fabrication of chalcogenide microstructures such as gratings, lenses and needles using a lithographically directed, evaporative self-organization of chalcogenide thin liquid films for the first time. Using a two-step annealing protocol, excess solvent of freshly coated ChG films is eliminated and then the liquid films are patterned using elastomeric masters with continuous or disconnected features during solvent evaporation. Although microcontact printing or capillary flow lithography has been proven to be useful to create continuous gratings and waveguide like structures in solid films, our method overcomes the limitation of structural continuity of the generated pattern and uses self-organization of solute ChG within the master's confinement to produce isolated microstructures. Fabrication of disjointed arrays of microlenses of various dimensions as well as conical shaped needles in ChG thin films has been demonstrated for relevant optical IR applications. This methodology establishes evaporative self-organization of ChG thin films as a viable alternative to creating microstructures in bulk ChG with hot-embossing, bypassing the need for ultra high temperature processing.