Photoinduced low refractive index in a photosensitive organic-inorganic hybrid material

A new organic-inorganic hybrid material, that shows photoinduced reduction of refractive index as well as volume contraction, has been prepared using a sol-gel method. Whereas previous photosensitive materials show a photoinduced increase in refractive index, this hybrid material shows a significant decrease in refractive index via the decomposition of methacrylate on light irradiation. Moreover, this hybrid material is patternable. The reduction of refractive index measured with a prism coupler was about 0.045, with a low refractive index value of 1.385 being observed. The structural change of the hybrid material on UV-light irradiation as monitored by FT-IR and energy dispersive X-ray spectroscopy (EDS) is investigated. Direct imprinting of the organic-inorganic hybrid material without any further steps (wet etching, thermal curing, or UV fixing) is also performed utilizing the volume contraction on light irradiation.