Mid‐Infrared Hyperbolic Metamaterial for the Silicon–Germanium Technology Platform

Hyperbolic metamaterials (HMMs) offer unprecedented control over light-matter interactions, yet integrating them into standard semiconductor platforms remains challenging. Here, we present the realization and optical characterization of a mid-infrared HMM based entirely on the silicon-germanium technology platform. The monolithic structure consists of alternating heavily doped (metal-like) and intrinsic (dielectric-like) germanium layers grown via CMOS-compatible ultra-high vacuum chemical vapor deposition (UHV-CVD). Using angle-resolved polarized reflectivity measurements, we experimentally demonstrate the emergence of a hyperbolic dispersion regime. The experimental optical response is accurately reproduced by a full multilayer model, which highlights the critical role of material losses when approaching the HMM spectral window. By simply adjusting the doping profile, this platform offers high design tunability and straightforward integration with mid-infrared photonic and plasmonic devices based on group-IV materials.