Realization of High-Quality Polymeric Photonic Structures by Two-Photon Polymerization

Two-photon polymerization (2PP) is a promising technique for additive manufacturing of 2D and 3D polymer structures with tailored physical properties. It provides the possibility to create structured samples with nearly arbitrary geometries. However, the potential of this technique to achieve structures with high resolution below the diffraction limit and complex geometries with high surface quality is not yet fully exploited. In this work, polymer gratings with controllable parameters, specially designed 3D structures with circularly symmetrical curved surfaces and 3D photonic resonators coupled with linear optical waveguides were demonstrated. In the first case, different photosensitive materials were applied for the fabrication of the gratings and their influence on the structure formation was compared. Furthermore, the approach to realize high resolution for feature sizes below the diffraction limit by controlling the laser focus position with respect to the glass substrate was shown. Periodic structures with a minimum feature size of 100nm and periodic distance of 200nm were realized. For special 3D structures with a circularly symmetrical curved shape, the main challenge was to realize smooth surfaces. An investigation of relevant influences and the optimization of processing parameters on the structure formation and surface quality were performed. Additionally, the 2PP fabrication of 3D resonators and waveguides with a nanoscale gap distance in between was studied.