Stimulated Emission of Surface Plasmons on Top of Metamaterials with Hyperbolic Dispersion

We have demonstrated that the stimulated emission of surface plasmons propagating on top of multilayered hyperbolic metamaterials coated with dye-doped polymeric films has a much lower (2.5–7 times) threshold than that on top of thick Ag films. This observation correlates with more than 2-fold shortening of the spontaneous emission kinetics on top of a lamellar metamaterial as compared to that on top of silver. The propagation of surface plasmons on top of the metamaterial and silver substrates was modeled (in the Otto geometry) using COMSOL Multiphysics. It has been shown that at given system parameters, the plasmon propagation loss in a metamaterial is smaller than that in silver by ∼14% and cannot explain the dramatic reduction of the lasing threshold observed experimentally in the metamaterial samples. We infer that the stimulated emission of propagating plasmons on top of a metamaterial is enhanced by the nonlocal dielectric environment and high local density of photonic states.