Advancing 3D direct-laser writing: leveraging optical metalenses for enhanced two-photon polymerization

Laser-based 3D printing, especially two-photon polymerization (2PP), is effective for creating sub-wavelength structures with applications in photonics, nanofluidics, NEMS, drug delivery, and tissue engineering. Traditionally, 2PP uses compound refractive lenses for precise light focusing. This work introduces an alternative using optical metalenses, which enhances 2PP's versatility and precision. By custom-tailoring the metalens point spread function, more complex geometries can be fabricated. We integrated metalenses into a custom 2PP system, experimentally validating this with 3D polymer microstructures. This advancement in 2PP technology allows for more intricate and sophisticated nanomanufacturing applications.