Low-loss infrared ultrawide type-II hyperbolic metamaterials based on III-V semiconductors

We have implemented a hyperbolic metamaterial covering a spectral bandwidth of 2000 inverse cm for wavelengths above 4.7 µm. A stack of intercalated heavily-doped InAs and undoped InAs epilayers was grown by molecular beam epitaxy with tellurium as the n-type dopant for obtaining electron concentrations of ~8e19 per cubic cm. The Type II hyperbolicity was determined through the effective optical constants deduced from infrared ellipsometry measurements of the stacks. The materials were then dry etched to form ID gratings with features ranging from 1 to 5 µm. The effective optical constants were used to model the grating's optical response by finite element electromagnetic calculations. The models showed the formation of hyperbolic plasmon polaritons at the same frequencies where experimental features were observed. This material is based upon work supported by the Office of the Undersecretary of Defense for Research and Engineering Basic Research Office STTR under Contract No. W911NF-21-P-0024. Disclaimer: The content of the information does not necessarily reflect the position or the policy of the Government, and no official endorsement should be inferred.