New UV-curable adhesives with variable refractive index based on inorganic-organic nanocomposites (NANOMER) for optical components

Abstract

New transparent UV-curable adhesives for the use in integrated optics based on organic-inorganic nanocomposites (NANOMER) have been developed. These adhesives show excellent optical properties, whereby a high content of SiO2 particles with an average particle size of 10 nm can be achieved (up to 35 vol-%). The thermal expansion coefficient could be reduced from 75 ppm/K down to 30 ppm/K with a filler content of 20 wt-% (15 vol-%). The refractive index could be varied from 1.450 (cured 1.461) to 1.546 (cured 1.558), at a wavelength of 644 nm, by variation of the synthesis. UV-curing was faster compared to UV-curable commercial epoxy resins.