Laser fabrication of crystalline silicon nanoresonators from an amorphous film for low-loss all-dielectric nanophotonics

TL;DR

This paper demonstrates a novel laser-based method to produce low-loss crystalline silicon nanoresonators from amorphous silicon films, enhancing their optical properties for nanophotonic applications.

Contribution

It introduces two innovative laser fabrication techniques for converting amorphous silicon into crystalline nanoresonators at large scale.

Findings

Crystalline silicon nanoparticles exhibit low optical losses.

Laser fabrication methods successfully produce resonant nanoresonators.

Optical and structural characterization confirm high quality of the nanoparticles.

Abstract

The concept of high refractive index subwavelength dielectric nanoresonators, supporting electric and magnetic optical resonances, is a promising platform for waveguiding, sensing, and nonlinear nanophotonic devices. However, high concentration of defects in the nanoresonators diminishes their resonant properties, which are crucially dependent on their internal losses. Therefore, it seems to be inevitable to use initially crystalline materials for fabrication of the nanoresonators. Here, we show that the fabrication of crystalline (low-loss) resonant silicon nanoparticles by femtosecond laser ablation of amorphous (high-loss) silicon thin films is possible. We apply two conceptually different approaches: recently proposed laser-induced transfer and a novel laser writing technique for large-scale fabrication of the crystalline nanoparticles. The crystallinity of the fabricated nanoparticles is proven by Raman spectroscopy and electron transmission microscopy, whereas optical resonant properties of the nanoparticles are studied using dark-field optical spectroscopy and full-wave electromagnetic simulations.