Monolithic CMOS-compatible zero-index metamaterials
  Zero-index materials exhibit exotic optical properties that can be utilized for integrated-optics applications. However, practical implementation requires compatibility with complementary metallic-oxide-semiconductor (CMOS) technologies. We demonstrate a CMOS-compatible zero-index metamaterial consisting of a square array of air holes in a 220-nm-thick silicon-on-insulator (SOI) wafer. This design is achieved through a Dirac-cone dispersion. The metamaterial is entirely composed of silicon and offers compatibility through low-aspect-ratio structures that can be simply fabricated in a standard device layer. This platform enables mass adoption and exploration of zero-index-based photonic devices at low cost and high fidelity. 
Daryl I. Vulis, Yang Li, Orad Reshef, Philip Camayd-Mu\~noz, Mei Yin,   Shota Kita, Marko Lon\v{c}ar, Eric Mazur
physics.optics