Parallel lithographic fabrication of micro-optical lenslets by photoexpansion in chalcogenide glasses

The non-locality of the photoexpansion effect as well as large volume changes observed in the fabrication of micro-lenses on the surface of As2S3 (chalcogenide) glass was investigated experimentally. The parallel photolithographic process was used in micro-lens and lens array fabrication because of its distinct advantages over focused light techniques. The process allowed excellent control on feature size. The non-local expansion gave smooth rounded edges and a sufficiently small exposure resulted in a convex structure. Smaller lenslets seemed to preserve their convex structure and showed higher aspect ratios.