Direct programming of confined Surface Phonon Polariton Resonators using the plasmonic Phase-Change Material In$_3$SbTe$_2$

TL;DR

This paper demonstrates the direct programming of confined surface phonon polariton resonators using a phase-change material, enabling reconfigurable nanophotonic components with enhanced mode confinement and complex geometries.

Contribution

It introduces a method to reconfigure SPhP resonators via phase-switching of In$_3$SbTe$_2$ on silicon carbide, advancing reconfigurable nanophotonics.

Findings

Reconfigurable SPhP resonators achieved with phase-change material.

Enhanced mode confinement up to λ/35.

Exploration of complex cavity shapes with unique field patterns.

Abstract

Tailoring light-matter interaction is essential to realize nanophotonic components. It can be achieved with surface phonon polaritons (SPhPs), an excitation of photons coupled with phonons of polar crystals, which also occur in 2d materials such as hexagonal boron nitride or anisotropic crystals. Ultra-confined resonances are observed by restricting the SPhPs to cavities. Phase-change materials (PCMs) enable non-volatile programming of these cavities based on a change in the refractive index. Recently, the new plasmonic PCM In$_3$SbTe$_2$ (IST) was introduced which can be reversibly switched from an amorphous dielectric state to a crystalline metallic one in the entire infrared to realize numerous nanoantenna geometries. However, reconfiguring SPhP resonators to modify the confined polaritons modes remains elusive. Here, we demonstrate direct programming of confined SPhP resonators by phase-switching IST on top of a polar silicon carbide crystal and investigate the strongly confined resonance modes with scanning near-field optical microscopy. Reconfiguring the size of the resonators themselves result in enhanced mode confinements up to a value of $\lambda/35$. Finally, unconventional cavity shapes with complex field patterns are explored as well. This study is a first step towards rapid prototyping of reconfigurable SPhP resonators that can be easily transferred to hyperbolic and anisotropic 2d materials.