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

Abstract

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.

A Click Chemistry Strategy for the Synthesis of Efficient Photoinitiators for Two‐Photon Polymerization

“…[ 48 ] The threshold values P th and D th determine the polymerization window, which is defined as the range of laser powers and scanning speeds that allow efficient two‐photon polymerization. Wide polymerization windows are critical for high throughput in mass production [ 49 ] and ensure reproducible results by buffering natural fluctuations in photoresist compositions. [ 50 ] Using the described method, it was possible to rapidly assess the polymerization characteristics and determine the polymerization windows in 30 different photoresist compositions.…”

Flexible Optical Interconnects via Thiol-ene Two-photon-induced Polymerization

“…These range from Organic Modified Ceramics (ORMOCER) 2 and other sol-gel based materials 3 to special glasses 4 , (meth)acrylates 5 and polydimethylsiloxane (PDMS) -based materials. [6][7][8] Crucial features are the extent of local refractive index increase, low optical damping and laser writing speed.…”

“…They exhibit also low optical damping and excellent thermal stability. These material class has been employed for the described application in a few studies, [6][7][8][9] where (meth)acrylate monomers were cured via 2PP inside crosslinked polysiloxane matrix films giving a local refractive index change. Getting a sample, where unreacted monomer is situated in a silicone rubber, is possible by either swelling the latter or by selectively curing the silicone formulation in mixture with the monomer formulation that does not participate in the crosslinking reaction.…”

Efficient Photoinitiators for Two-Photon Polymerization

“…In research, this technique already proved successful in fabricating photonic crystals, 3 microfluidics, 4,5 microelectrical and micromechanical systems 6,7 as well as polymer-based optical waveguides. [8][9][10] As 2PP allows the exact reconstruction of cell-specific sites in 3D at micro-and nanometer precision, 11-13 the manufacturing of biocompatible structures is another promising application. Furthermore, 2PP can be processed at IR and NIR wavelengths, where biological tissues exhibit a window of transparency.…”