We propose modification to gain spectra of semiconductor quantum heterostructures by incorporation of nanostructured metal, paving the way for tailor made “meta-gain” media. We show that the wavelength dependence of the principal direction of energy propagation in media with hyperbolic dispersion leads to blue-shifting of peak photoluminescence (PL), and thereby optical gain, relative to emission from the bare semiconductor. Additionally we show that emission spectra from metal-semiconductor hyperbolic metasurfaces depends strongly upon the polarization of an external optical pump. The simultaneous co-optimization of pump properties and optical and electronic densities of states provides a platform for not only compensating losses in metallic metamaterials, but also designing emission spectra beyond that provided by the constituent quantum heterostructures.
We study the spontaneous emission enhancement inside a hyperbolic metamaterial, composed of a periodic stack of silver and silicon layers. After showing that the decay rate outside the multilayer can be spectrally altered via the metallic filling ratio, we embed the source within the individual silicon layers, and predict a 3-fold increase of the Purcell factor with respect to its outer value. Then we include the emitter in a polymethyl-methacrylate (PMMA) layer, and extract the plasmonic modes by means of a triangular and a rectangular grating, obtaining respectively a 10-fold and 6-fold enhancement in the power emitted into the far-field.