Amorphous Selenium Mie Resonators for Infrared Meta-Optics

TL;DR

This paper introduces a chemical vapor deposition method to create amorphous selenium Mie resonators that exhibit tunable mid-infrared resonances, high absorption, and ultra-high-Q resonances when coupled with ENZ substrates, advancing nanophotonic applications.

Contribution

The study presents a scalable CVD process for amorphous selenium spheres with tunable Mie resonances in the mid-infrared range, enabling new nanophotonic device functionalities.

Findings

Size-tunable Mie resonances from 2 to 16 micrometers.

Achieved absorption dips up to 90% in ensembles.

Observed ultra-high-Q resonances with ENZ substrates.

Abstract

Applying direct growth and deposition of optical surfaces holds great promise for the advancement of future nanophotonic technologies. Here, we report on a chemical vapor deposition (CVD) technique for depositing amorphous selenium (a-Se) spheres by desorption of selenium from Bi2Se3 and re-adsorption on the substrate. We utilize this process to grow scalable, large area Se spheres on several substrates and characterize their Mie-resonant response in the mid-infrared (MIR) spectral range. We demonstrate size-tunable Mie resonances spanning the 2-16 um spectral range, for single isolated resonators and large area ensembles, respectively. We further demonstrate strong absorption dips of up to 90% in ensembles of particles in a broad MIR range. Finally, we show that ultra-high-Q resonances arise in the case where Se Mie-resonators are coupled to low-loss epsilon-near-zero (ENZ) substrates. These findings demonstrate the enabling potential of amorphous Selenium as a versatile and tunable nanophotonic material that may open up avenues for on-chip MIR spectroscopy, chemical sensing, spectral imaging and large area metasurface fabrication.