The METANEXT project has delivered several key innovations that significantly advance the state of the art in nanophotonics and materials science. Foremost among these is the demonstration of van der Waals heterostructure metasurfaces (vdW-HM), which constitutes a paradigm shift in the design of photonic systems. Whereas previous approaches positioned two-dimensional (2D) materials in the vicinity of prefabricated metasurfaces, our methodology directly constructs the photonic architecture from the 2D materials themselves. This enables unprecedented control over light-matter interactions and led to the observation that strong coupling can be saturated with power levels up to three orders of magnitude lower than in prior systems. Such ultra-low-power operation renders these devices highly promising for integration into on-chip quantum devices and photonic circuitry.
A second major contribution is the development of dual-gradient metasurface. While single-gradient metasurfaces have been explored previously, the feasibility of independently controlling two optical parameters (i.e. resonance wavelength and quality factor) within a single device was previously unproven. METANEXT has successfully realized this concept, achieving a mode density that approached the theoretical limit for metasurfaces in a compact footprint. This platform thus offers a powerful new tool for fundamental and applied research, with potential to accelerate discoveries in material characterization, photocatalysis, nonlinear optics, and molecular sensing.
To ensure the further uptake of these results, several key needs should be met. (1) The platform should be extended to additional 2D materials in order to uncover new physical phenomena and enable the realization of fully operational quantum photonic devices, such as on-demand single-photon emitters and chiral laser sources. (2) Scalable fabrication processes should be explored to facilitate the transition from laboratory-scale demonstrations to wafer-level manufacturing, which will be necessary for commercial viability and integration with complementary metal-oxide-semiconductor (CMOS) technology. (3) The project must establish effective pathways for knowledge transfer and collaboration with industrial stakeholders in quantum technologies, sensing, and telecommunications, thereby facilitating the translation of these disruptive device concepts into practical, real-world applications. METANEXT is already committed to a multi-2D-material approach and possible large-scale fabrication approaches, and we will leverage the continuing dissemination of the project results in high-impact publications as well as at conferences and trade fairs to effectively establish links with industrial partners.
