High Photosensitive Sol-Gel Hybrid Materials for Direct Photo-Imprinting of Micro-Optics

Sol-gel derived inorganic-organic hybrid materials (HYBRIMERs) were found to have high photosensitivity arising from large changes in refractive index and volume upon exposure to light. These materials combined different photosensitive mechanisms due to the presence of polymers and silica in the HYBRIMER structure. Photo-induced densification of a germanium-doped HYBRIMER gave an increase in refractive index accompanying a volume contraction. A methacrylate HYBRIMER was decomposed by long UV illumination, giving a low refractive index and resulting in a reduction in film thickness. Also, photo-initiators were locked inside the methacrylate HYBRIMER during illumination, giving a simultaneous increase in the refractive index and film thickness. Direct photo-imprinting using the photosensitive HYBRIMER was demonstrated for simple fabrication of gratings, microlens, and waveguides using a photomask, a phase mask, an interferometer, and laser writing.