Enhancing Two-Photon Polymerization Productivity: Beam Shaping and Parallelization via Spatial Light Modulators

Two-Photon Polymerization (2PP) has been established in recent decades as one of the most promising additive manufacturing processes for the fabrication of freeform 3D micro- and nanostructures. In 2PP, the photochemical reaction, induced by the absorption of the energy of two photons, is confined to a small and well-defined region of the space known as voxel, enabling the manufacture of 3D features with high accuracy and resolutions in the submicrometric range. Unfortunately, 2PP shows some drawbacks, among which its low productivity appears as one of its main limitations nowadays. In this regard, different approaches have recently been explored aiming at increasing 2PP throughput, like the use of Spatial Light Modulators (SLMs), which allows dynamically adjusting the shape of the laser beam into different geometries, patterns or even complex images. In this work an experimental 2PP setup comprising a femtosecond visible laser in combination with high accuracy linear stages and different optical solutions including an SLM has been used to explore the improvement achieved in productivity and additional advantages for the manufacturing of different 2.5 and 3D microstructures. A commercial photoresist has been used as base for these experiments, adjusting its photoinitiator content to obtain the optimal sensitivity to the wavelength provided by the laser.