Modified photoresins with tunable refractive index for 3D printed micro-optics

Modern two-photon lithography (TPL) technologies provide convenient methods for 3D printing sub-micron featured structures in photopolymers. TPL is a valuable tool for rapid prototyping of micro-optics, photonic metamaterials, and nanostructures. The ability to tune the optical properties of the resin materials used for TPL greatly expands the capabilities of 3D printing these types of components. Here we couple a sol-gel method of synthesizing and functionalizing titanium dioxide (TiO 2 ) nanoparticles to modify off-the-shelf commercial resins designed for TPL to tune the refractive index of the 3D printable resin. The range of refractive indices expands up to 1.66 at 633 nm which is higher than commercially available, unmodified resins at that wavelength.