Van der Waals heterostructure metasurfaces: atomic-layer assembly of ultrathin optical cavities

TL;DR

This paper introduces van der Waals heterostructure metasurfaces, combining 2D materials and metasurfaces to create ultrathin optical cavities that exhibit strong light-matter interactions and polaritonic luminescence at room temperature.

Contribution

It presents a novel integration of layered 2D materials with metasurfaces to form resonant nanostructures, enabling ultrathin optical cavities with enhanced light-matter coupling.

Findings

Room-temperature strong coupling observed in vdW heterostructure metasurfaces

Saturation of strong-coupling regime at ultralow fluences <1 nJ/cm2

Demonstration of polaritonic luminescence in ultrathin cavities

Abstract

Photonics has been revolutionized by breakthroughs in optical metasurfaces and layered two-dimensional materials. Yet, integrating these two fields in a singular system has remained challenging. Here, we introduce the concept of van der Waals (vdW) heterostructure metasurfaces, where ultrathin multilayer vdW material stacks are shaped into precisely engineered resonant nanostructures for boosting light-matter interactions. By leveraging quasi-bound states in the continuum to create intrinsic cavities from WS$_2$ monolayers encapsulated in hexagonal boron nitride, we observe room-temperature strong coupling and polaritonic luminescence, which further unveils a saturation of the strong-coupling regime at ultralow fluences <1 nJ/cm2, more than three orders of magnitude smaller than in previous 2D-cavity systems. Our approach, seamlessly merging metasurfaces and vdW materials, unlocks new avenues for ultrathin optical devices with atomic-scale precision and control.