Scaling laws of voxels in two-photon photopolymerization nanofabrication

Understanding the performance of individual voxels is critical to establish two-photon photopolymerization as a nanoprocessing tool. In this letter, we report that at near-threshold exposure condition voxel shape scaling follows different laws in the courses of varying laser power and changing exposure duration. The voxel aspect ratio, when exposure enhanced, monotonically increases and reaches a saturation status for the two processes that are conventionally regarded as equivalent for voxel volume tuning. A growth model that deals with fine photopolymerization process occurring at the submicron-focal volume is proposed and applied to interpret the unexpected phenomenon. (C) 2003 American Institute of Physics.