Acrylate-based photopolymer for two-photon microfabrication and photonic applications

This paper provides a photopolymerizing material suitable for stereolithography of complex submicrometer-sized three-dimensional (3D) structural elements to a broad scientific public. Here, we present the formulation of a polymer (LN1 resin) that allows further research in the field of nanofabrication and -technology as it surpasses current material limitations. The polymer consists of multifunctional acrylate oligomers as binder, polyfunctional, monomers, and a photoinitiator (PI). The chemistry to form 3D structures is based on photopolymerization of the acrylate system initiated by free-radical species that are triggered by two-photon absorption of a PI. Important parameters of photocuring, such as the effects of PI concentration, temperature, and light intensity, were studied using photocalorimetry. The thermal stability of the material was tested using thermal gravimetric analysis, providing key information for electronic and photonic applications. Photonic-crystal structures generated from this resin exhibiting photonic stop gaps in near-infrared- and telecommunication-wavelength regions are presented.