Optimizing the geometry and losses in hyperbolic metamaterials

Fermi's golden rule shows that the spontaneous emission lifetime of quantum emitters is directly connected to the local density of states. Hyperbolic metamaterials
are extremely anisotropic materials with iso-frequency surfaces as hyperboloids
and not as ellipsoids as in natural materials. These hyperbolic materials give
an extremely large photonic density of states for positions near the material.
Classically, the hyperbolic properties are achieved by two main approaches: a
metal-dielectric superlattice with subwavelength layer thicknesses or a metallic
nanowire lattice embedded in a dielectric host. In the visible regime the presence
of metals leads to important losses that are a constraint for many applications.
We numerically study the possibility to keep the hyperbolic properties even when
limiting the use of metal in the structure.