Computational voxel control in two-photon lithography via a generalized compact model

Two-photon lithography (TPL) enables freeform 3D micro- and nanofabrication through nonlinear absorption and localized polymerization. Modeling voxel formation requires coupling nonlinear optical dose deposition with local photopolymerization kinetics and mass transport of reactive and inhibiting species. In this work, we employ a generalized compact model for TPL to quantify how optical and resist parameters govern voxel dimensions and shape. We first contrast this framework with simple intensity-threshold models, demonstrating that the compact model incorporates resist behaviors in voxel formation. We then explore how exposure dose, oxygen, quencher loading, and beam shaping control voxel width, height, and aspect ratio. We systematically study the effects of numerical aperture, fill factor, and polarization, and we evaluate how entrance-pupil amplitude and phase modulation reshape the point spread function (PSF), thereby controlling the lateral and axial extent of the polymerized voxel. We further introduce a spatial coherence factor to model partially coherent illumination at the entrance pupil and discuss how reduced spatial coherence modifies the PSF and voxel geometry. Across a range of amplitude and phase patterns, we demonstrate the tunability of voxel aspect ratio and morphology. In particular, ring-amplitude illumination produces needle-like, high-aspect-ratio voxels, while combining ring amplitude with a spiral (vortex) phase mask generates voxels with flattened top and bottom surfaces. Overall, these results provide practical guidance for tuning the optical configuration and resist parameters to achieve targeted voxel geometries in TPL.