Simultaneous Dual-Plane Multi-Write-Spot Two-Photon Polymerization Using a Single Diffractive Optical Element
The serial nature of two-photon polymerization (2PP) limits fabrication throughput. While diffractive optical elements (DOEs) can be used to generate multiple write spots in a single plane, three-dimensional structures still require sequential layer-by-layer fabrication. We demonstrate a dual-plane multi-spot 2PP approach using a single static DOE capable of generating two independent focal-spot arrays in distinct planes. This configuration enables simultaneous fabrication of two layers during continuous scanning while maintaining a simple scanning strategy compatible with woodpile structures. Using 29 write spots distributed across two planes separated by 1.8 $\mu$m, we fabricate four-layer woodpile structures with an effective writing speed of 1 mm 2 in 90 s. The results demonstrate that combining multi-write-spot parallelization with simultaneous multi-plane writing provides a powerful route to significantly increase 2PP fabrication throughput.