We report the use of an amplified femtosecond laser for single-shot two-photon exposure of the commercial photoresist SU-8. By scanning of the focal volume through the interior of the resist, three-dimensional (3-D) structures are fabricated on a shot-by-shot basis. The 800-nm two-photon exposure and damage thresholds are 3.2 and 8.1TW/cm2, respectively. The nonlinear nature of the two-photon process allows the production of features that are smaller than the diffraction limit. Preliminary results suggest that Ti:sapphire oscillators can achieve single-shot two-photon exposure with thresholds as low as 1.6TW/cm2 at 700 nm, allowing 3-D structures to be constructed at megahertz repetition rates.
© 1998 Optical Society of America
George Witzgall, Rutger Vrijen, Eli Yablonovitch, Vinh Doan, and Benjamin J. Schwartz, "Single-shot two-photon exposure of commercial photoresist for the production of three-dimensional structures," Opt. Lett. 23, 1745-1747 (1998)