Laser-Induced Spatially-Selective Tailoring of High-Index Dielectric Metasurfaces

TL;DR

This paper introduces a laser-based post-processing method for high-index dielectric metasurfaces that enables spatially-selective modifications, enhancing tunability and scalability beyond traditional fabrication techniques.

Contribution

It presents a novel ultrashort laser pulse technique that exploits resonant behavior for precise, localized modifications of dielectric metasurfaces, reducing fabrication complexity.

Findings

Achieved spatial pixelation of large-scale metasurfaces

Demonstrated height modification of metasurface elements

Enabled selective heating and customization

Abstract

Optically resonant high-index dielectric metasurfaces featuring Mie-type electric and magnetic resonances are usually fabricated by means of planar technologies, which limit the degrees of freedom in tunability and scalability of the fabricated systems. Therefore, we propose a complimentary post-processing technique based on ultrashort ($\leq$ 10 ps) laser pulses. The process involves thermal effects: crystallization and reshaping, while the heat is localized by a high-precision positioning of the focused laser beam. Moreover, for the first time, the resonant behavior of dielectric metasurface elements is exploited to engineer a specific absorption profile, which leads to a spatially-selective heating and a customized modification. Such technique has a potential to reduce the complexity in the fabrication of non-uniform metasurface-based optical elements. Two distinct cases, a spatial pixelation of a large-scale metasurface and a height modification of metasurface elements, are explicitly demonstrated.