Fabrication of functional micro–nano structures using phase holographically modulated femtosecond laser technology: a review

Micro–nano fabrication technology is critical to high-end fabrication, bridging the gap between microscopic and macroscopic scales. Femtosecond laser fabrication, owing to its ultrafast nonlinear effects and three-dimensional direct writing capabilities, has demonstrated unique advantages in the fabrication of functional micro–nano structures. Phase holographically modulated femtosecond laser technology, as a representative of spatial optical field modulation, modulates the phase of the incident laser field to flexibly transform a single focal point into various spatial optical fields, including multifocal arrays, patterned optical fields, and three-dimensional optical fields, according to specific fabrication requirements. This technology not only improves fabrication precision and efficiency but also provides greater flexibility in femtosecond laser fabrication. This review systematically summarizes recent technological advances, focusing on four aspects: algorithms for generating phase holograms, exceeding the diffraction limit to improve fabrication resolution, optimizing fabrication quality, and improving fabrication efficiency. It aims to provide theoretical foundations and technical references to support the practical application of modulated femtosecond laser technology in the fabrication of functional micro–nano structures.