Nanoscale reshaping of resonant dielectric microstructures by light-driven explosions

Abstract

Femtosecond-laser-assisted material restructuring employs extreme optical intensities to localize the ablation regions. To overcome theminimum feature size limit set by thewave nature of photons, there is a need for newapproaches to tailored material processing at the nanoscale. Here,we report the formation of deeply-subwavelength features in silicon, enabled by localized laserinduced phase explosions in prefabricated silicon resonators. Using short trains of mid-infrared laser pulses, we demonstrate the controllable formation of high aspect ratio (>10:1) nanotrenches as narrow as ∼λ=80. The trench geometry is shown to be scalable with wavelength, and controlled bymultiple parameters of the laser pulse train, such as the intensity and polarization of each laser pulse and their total number. Particle-in-cell simulations reveal localized heating of silicon beyond its boiling point and suggest its subsequent phase explosion on the nanoscale commensurate with the experimental data. The observed femtosecond-laser assisted nanostructuring of engineered microstructures (FLANEM) expands the nanofabrication toolbox and opens exciting opportunities for high-throughput optical methods of nanoscale structuring of solid materials.

Publication Link: https://doi.org/10.1038/s41467-023-42263-w