Microstructuring by Two-Photon Polymerization using a Sub-Nanosecond Laser

A multi-photon absorption-based laser writing system with sub-micrometer resolution has been developed using an inexpensive sub-nanosecond laser for two- and three-dimensional structuring in photosensitive resist materials. New combinations of commercially available photoresists such as SU-8 and AR-N 4340, and a photo initiator (2, 4, diethyl-9H-thioxanten-9-one) with large two-photon absorption at 532 nm are shown to be effective in obtaining sub-micrometer line or dot resolution. Systematic studies of the resolution on the system and fabrication parameters such as laser power, writing speed, focusing arrangement, etc. have been carried out. The sub-nanosecond-based laser micro writer is an inexpensive alternative with similar capabilities as a femtosecond-based laser writer. This system is comparably effective and has much higher capabilities for 2D structuring in terms of the aspect ratio of the fabricated structures than conventional 2D laser micro writers.