Canalization acoustic phonon polaritons in metal-MoO3-metal sandwiched structures for nano-light guiding and manipulation

TL;DR

This paper theoretically explores highly confined, directional acoustic phonon polaritons in metal-MoO3-metal structures, demonstrating their potential for ultra-scale nano-light guiding and manipulation.

Contribution

It introduces a novel layered structure for in-plane anisotropic acoustic phonon polaritons with tunable propagation properties and extreme electromagnetic confinement.

Findings

APhPs are highly directional and confined

Twisting MoO3 layers modulates polaritonic coupling

Structures outperform other phonon-polariton modes in confinement

Abstract

We theoretically propose and study in-plane anisotropic acoustic phonon polaritons (APhPs) based on a layered structure consisting of a monolayer (or few layers) {\alpha}-phase molybdenum trioxide ({\alpha}-MoO3) sandwiched between two metal layers. We find that the APhPs in the proposed sandwiched structures are a canalization (highly directional) electromagnetic mode propagating along with the layers and at the same time exhibit extreme electromagnetic-field confinement surpassing any other type of phonon-polariton modes. When a double layer of {\alpha}-MoO3 is sandwiched by two Au layers, twisting the two {\alpha}-MoO3 layers can adjust the interlayer polaritonic coupling and thus manipulate the in-plane propagation of the highly confined APhPs. Our results illustrate that the metal-MoO3-metal sandwiched structures are a promising platform for light guiding and manipulation at ultimate scale.