Three-dimensional structures fabricated after laser-induced free radical generation in azoaromatic compounds

Three-dimensional microstructures with selective properties have often been developed for optical and photonic applications. The simplest way to achieve optically active structures is by the functionalization of host matrices using, for instance, organic dyes. Laser fabrication techniques, such as two-photon polymerization, allow manufacturing devices quickly, with high resolution, without shape limitation, among other many advantages. In this work, we demonstrate the fabrication of three-dimensional microstructures via two-photon polymerization, using azobenzene-based dyes as photoinitiator, the compound responsible for absorbing the light and start the polymerization. When a high photoinitiator concentration is used (for instance 1.00 wt%), a significant amount of dye remains unchanged into the final structures, and its optically induced birefringence could be investigated. Therefore, the azobenzene-based dye acts, at the same time, as the photoinitiator and functionalizer.