Three-dimensional micro-fabrication using two-photon absorption by femtosecond laser

As a femtosecond laser has recently been developed, both of high power and high photon density are easily obtained. The high photon density results in photopolymerization of urethane acrylate resin whose absorption spectrum is shorter than that of the femtosecond laser. The stereo-lithography using the two-photon absorption (TPA) makes micro structures with great resolution. We have used this phenomenon to make micron-sized structures with sub-micron resolution. Before fabricating 3-D structures, precise 2-D structures have been performed. Furthermore the TPA photopolymerization is applied to poly-dimethyl siloxane (PDMS) molding. In this paper, we report the recent progress and application of this technology in our laboratory.