Doubly patternable epoxy based sol–gel structures by UV and soft lithography

The sol–gel synthesis of hybrid materials offers special opportunities to combine polymer and glass properties and to create promising candidates for photonic applications.We report on the optical and morphological characterization of a new photosensitive epoxy based sol–gel system. Germanium ethoxide and 3-Glycidoxypropyltrimethoxysilane were used as precursors for hybrid sol-gel planar coatings. A photoacid generator was added to solution in order to allow the epoxy photopolymerization when the films are selectively exposed to UV light. The refractive index increase (Δn = 0.015) induced by UV light allows the direct patterning of waveguiding structures having good morphological quality. Stripes and beam splitters were defined by direct UV exposition on silicon substrates. Moreover, we present structures made by thermal imprinting method. Silicon masters have been used to transfer relief gratings on the photopolymerizable epoxy sol-gel materials. Combining thermal imprinting technique and UV light exposition through a photomask, complex structures can be realized such as light couplers, sensors and wavelength filters.