A deep-UV plasmonic nanolaser with hyperbolic metamaterials

In recent years, plasmonic nanostructured materials have been used to enhance light emission by creating localized electric fields that confine light fields to regions below the diffraction limit of the material, resulting in efficient lightmatter interactions.1 Plasmonic nanolasers based on these materials have been developed by using, for example, a dielectric nanowire or nanorod gain material—the laser amplification medium—placed on a metal film or silica/metal structure to form a Fabry-Pérot cavity resonator (an arrangement of mirrors for multiple light reflection).2, 3 However, the nanowire or nanorod length in these plasmonic nanolasers is often fairly long (several micrometers) and it is not easy to control the nanowire/nanorod orientation, which limits the potential applications of these devices. Here, we discuss our recent work using a metal-dielectric hyperbolic metamaterial (HMM)—a material engineered to exhibit extreme anisotropy upon interaction with light—as a plasmonic cavity to demonstrate a 289nm UV plasmonic nanolaser. Although the quantum well heterostructures used in these nanolasers, which increase the strength of electro-optical interactions, have a low internal quantum efficiency of 30%, the strong light-matter coupling introduced by the HMM plasmonic cavity can still bring the devices above the lasing threshold. The dispersion relation (the effect of a dispersive medium on the properties of a light wave) of the stacked metal-dielectric HMM is given by: