Gradient polaritonic surface with space-variant switchable light-matter interactions in 2D moire superlattices

TL;DR

This paper introduces natural gradient polaritonic surfaces in moire superlattices, enabling dynamic control of light-matter interactions and polariton propagation at the nanoscale with low losses and high confinement.

Contribution

It demonstrates the use of moire superlattices in twisted bilayer graphene to achieve switchable and tunable polariton interactions and directional control, advancing nanoscale light manipulation.

Findings

On-off switching of polariton-soliton interactions

Continuous modulation of local polariton states

Generation of directional polaritons with electrical control

Abstract

Polaritons in two-dimensional (2D) materials provide unique opportunities for controlling light at nanoscales. Tailoring these polaritons via gradient polaritonic surfaces with space-variant response can enable versatile light-matter interaction platforms with advanced functionalities. However, experimental progress has been hampered by the optical losses and poor light confinement of conventionally used artificial nanostructures. Here, we demonstrate natural gradient polaritonic surfaces based on superlattices of solitons-localized structural deformations-in a prototypical moire system, twisted bilayer graphene on boron nitride. We demonstrate on-off switching and continuous modulation of local polariton-soliton interactions, which results from marked modifications of topological and conventional soliton states through variation of local strain direction. Furthermore, we reveal the capability of these structures to spatially modify the near-field profile, phase, and propagation direction of polaritons in record-small footprints, enabling generation and electrical switching of directional polaritons. Our findings open up new avenues toward nanoscale manipulation of light-matter interactions and spatial polariton engineering through gradient moire superlattices.