Light extraction from high-k modes in a hyperbolic metamaterial
  Hyperbolic Metamaterials (HMMs) have recently garnered much attention because they possess the ability for broadband manipulation of the photon density of states and sub-wavelength light confinement. These exceptional properties arise due to the excitation of electromagnetic states with high momentum (high-k modes). However, a major hindrance to practical applications of HMMs is the difficulty in coupling light out of these modes because they become evanescent at the surface of the metamaterial. Here we report the first demonstration of out-coupling of high-k modes in an active HMM using a high-index contrast bulls-eye grating. Quantum dots embedded inside the metamaterial are used for local excitation of high-k modes. This demonstration of light out-coupling from quantum dots embedded in a HMM could pave the way for developing practical photonic devices using these systems. 
T. Galfsky, H. N. S. Krishnamoorthy, W. Newman, E. E. Narimanov, Z.   Jacob, V. M. Menon
physics.optics