Titania-Based Spherical Mie Resonators Elaborated by High-Throughput Aerosol Spray: Single Object Investigation

TL;DR

This paper demonstrates a high-throughput aerosol spray method to create TiO2 spherical nanoantennas that exhibit sharp Mie resonances, structural colors, and high directivity, enabling advanced photonic applications at visible and near-UV frequencies.

Contribution

It introduces a novel aerosol-spray fabrication process for TiO2 spheres with verified optical resonances, expanding possibilities for all-dielectric nanoantennas in photonics.

Findings

Spectroscopic evidence of sharp Mie resonances in individual particles

Structural colors observed matching theoretical predictions

High directivity achieved due to high permittivity material

Abstract

In the framework of photonics with all-dielectric nanoantennas, sub-micro-metric spheres can be exploited for a plethora of applications including vanishing back-scattering, enhanced directivity of a light emitter, beam steering, and large Purcell factors. Here, the potential of a high-throughput fabrication method based on aerosol-spray is shown to form quasi-perfect sub-micrometric spheres of polycrystalline TiO 2 . Spectroscopic investigation of light scattering from individual particles reveals sharp resonances in agreement with Mie theory, neat structural colors, and a high directivity. Owing to the high permittivity and lossless material in use, this method opens the way toward the implementation of isotropic meta-materials and forward-directional sources with magnetic responses at visible and near-UV frequencies, not accessible with conventional Si- and Ge-based Mie resonators.