Two-photon-induced Microfabrication of Flexible Optical Waveguides

The Two-photon induced polymerization (2PP) is a novel concept in photopolymer chemistry allowing for elegant 3D direct laser writing (DLW) with resolutions down to several tens of nanometers. It has attracted significant attention in fields such as micro-electromechanical systems (MEMS), photonic crystals or surface plasmon polaritons. Additionally, 2PP can be applied for the structuring of optical waveguides by inducing a local refractive index increase over the surrounding cladding material. Herein, we present our latest work regarding high performance waveguides on the basis of polysiloxane/photopolymer hybrid materials, which we consider to be useful in the communication technology. High refractive acrylic formulations were cured via 2PP in polysiloxane films. In comparison to former works the procedure could be significantly simplified by using a thixotropic, monomer-containing polysiloxane matrix formulation, which could be UV-cured after DLW. The enrichment of monomer during the DLW process in the illuminated regions enabled us to create a refractive index increase over the surrounding material and thus eliminating the impractical evaporating of the excess monomer by simply UV-curing the whole sample after 2PP-structuring. DLW of waveguide structures was carried out using our novel two-photon initiator B3FL.