Atomically layered materials for next-generation metasurfaces

Atomically layered materials composed of individual atomic planes bonded together by weak van der Waals (vdW) interactions have sparked a revolution in solid state physics due to their unique electronic properties and capability for forming multi-material heterostructures with atomically sharp interfaces. However, accessing fundamental electronic excitations of two-dimensional (2D) materials optically has so far been a major challenge due to the associated low absorption cross sections and their low environmental stability. METANEXT will establish a new paradigm for amplifying and harnessing light-matter interactions in 2D materials by shaping vdW heterostructures into the resonant building blocks of optical metasurfaces. At the core of the proposed platform is the implementation of nanostructured hexagonal boron nitride (hBN) as a photonically active material, pushing beyond its currently prevalent use as a passive buffer layer in optoelectronics. Leveraging the emerging concept of optical bound states in the continuum, I will use my extensive experience in nanophotonic engineering to design and experimentally realize hBN-based metasurfaces with ultrasharp resonances incorporating mono- and few-layer systems of vdW materials, allowing direct optical access to such 2D systems with unprecedented efficiency and spectral/spatial control over the excitation. Specifically, I will utilize the METANEXT platform to (1) push the limits of light-matter coupling in black phosphorus heterostructures, (2) greatly boost the efficiency of single-photon generation from localized defects in atomically thin molybdenum disulfide (MoS2), and to (3) realize a completely new concept for valley-dependent on-chip lasing from transition metal dichalcogenide (TMD) monolayers. METANEXT will deliver both fundamental insights into the optical excitation mechanisms of current and future 2D materials as well as important conceptual advances for practical chip-integrated quantum light sources.