Integrated optical devices based on broadband epsilon-near-zero   meta-atoms
  We verify the feasibility of the proposed theoretical strategy for designing the broadband near-zero permittivity (ENZ) metamaterial at optical frequency range with numerical simulations. In addition, the designed broadband ENZ stack are used as meta-atoms to build functional nanophotonic devices with extraordinary properties, including an ultranarrow electromagnetic energy tunneling channel and an ENZ concave focusing lens. 
Lei Sun, Kin Wah Yu, and Xiaodong Yang
physics.optics