Silica-Based, Organically Modified Host Material for Waveguide Structuring by Two-Photon-Induced Photopolymerization

The three‐dimensional fabrication of optical waveguides has gained increasing interest in recent years to establish interconnections between electrical components on a very small scale where copper circuits encounter severe limitations. In this work the application of optically clear, organically modified porous silica monoliths and thin films as a host material for polymeric waveguides to be inscribed into the solid host structure by two‐photon‐induced photopolymerization is investigated. Porosity is generated using a lyotropic liquid crystalline surfactant/solvent system as a template for the solid silica material obtained by a sol–gel transition of a liquid precursor. In order to reduce the brittleness of the purely inorganic material, organic–inorganic co‐precursor molecules that contain poly(ethylene glycol) chains are synthesized and added to the mixture, which successfully suppresses macroscopic cracking and leads to flexible thin films. The structure of the thus‐obtained porous organic–inorganic hybrid material is investigated by atomic force microscopy. It is shown that the modified material is suitable for infiltration with photocurable monomers and functional polymeric waveguides can be inscribed by selective two‐photon‐induced photopolymerization. An approach for waveguide structuring by means of two‐photon‐induced photopolymerization is demonstrated (see figure). The approach is based on the use of a porous silica host material, which can be infiltrated by a high refractive index monomer. In order to counteract the brittleness of porous silica, the host material is modified by the use of a poly(ethylene glycol)‐based co‐precursor.