Multilayer hyperbolic metamaterial based on alternating TiO2/Cu layers

A multilayer hyperbolic metamaterial (HMM), fabricated from alternating thin films of metal and dielectric, displays a hyperbolic, anisotropic dispersion relation due to the coupling of excited surface plasmons. The design, fabrication, and characterization of an HMM based on TiO2 / Cu alternating layers with a metal-to-dielectric fill factor of 67% is presented. The layers were deposited onto glass and silicon substrates using physical vapor deposition (PVD) with an electron beam evaporator and then characterized using ellipsometry. According to the effective medium theory, this design shows an epsilon-near-zero (ENZ) line near the Helium-Neon wavelength of 633 nm. Our experimental measurements are in good agreement with the theoretical predictions.