Functional epoxy polymer for direct nano-imprinting of micro-optical elements

This work presents a functional resist for the direct fabrication of micro-optical elements with UV-enhanced substrate conformal imprint lithography (UV-SCIL). This functional resist is based on a UV-curable epoxy polymer where TiO2 nanoparticles are enclosed. Adding these particles to the polymer raises the refractive index of the functional resist with raising particle content from 1.52 up to 1.64 at a wavelength of 633 nm. Therefore, the refractive index can be matched for many micro-optical applications. Here, multilevel Fresnel lenses from a 200 mm silica substrate are transferred into the functional resist by UV-SCIL with nanometer resolution and high structure fidelity.