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

Abstract

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.