Three-Dimensional Microfabrication by Two-Photon Polymerization

This chapter will focus on a particular LDW process that employs ultrashort pulsed lasers and photopolymerizable precursors two-photon polymerization (TPP). Also known as two-photon induced photopolymerization and two-photon 

Generating Micro- and Nanopattems on Polymeric Materials. Edited by A. del Campo and E. Arzt Copyright 2011 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978.3-527-32508-5 

Although two-photon excitation can be induced by using continuous wave lasers, pulsed lasers are preferable because they can achieve the same excitation efficiencies with much lower average powers due to their higher peak intensities. Specifically, the power of a continuous wave laser has to be higher than the average power of 

Two-photon polymerization offers a unique combination of advantages. First, no topological constraints are present in the fabrication of a 3D microstructure. Second, sub-diffraction-limited resolution can be attained by employing laser intensities just 

800 nm from a mode-locked Ti sapphire laser causing two-photon excitation in the dye solution. Only when absorption occurs nonlinearly, is the excitation confined to the objective focal plane. 

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