Exceptional mode organization in a resonator microcavity based on a hyperbolic metamaterial

Abstract

Hyperbolic metamaterials (HMMs) offer a variety of exciting possibilities for manipulation of light among which are e.g. spontaneous emission enhancement and negative refraction [1]. Recently, studies of arrays of three-dimensional hyperbolic microcavities have revealed anomalous scaling laws [2]. To investigate the fundamentals of this behaviour in detail, we turn to a two-dimensional system consisting of a HMM based on stacked layer pairs of ZnO/ZnO:Ga embedded in a single resonator microcavity. The cavity with the enclosed HMM is grown monolithically by molecular beam epitaxy (MBE) [3]. For the extraordinary wave (transversal magnetic (TM) polarization) the highly anisotropic and frequency dependent HMM refractive index enables a unique distribution of resonant modes. In a cavity with the fixed length L several modes of the same order can exist at different frequencies and the relative spectral positions of higher and lower order modes can interchange resulting in an anomalous mode organization. Furthermore, the HMM medium gives rise to additional modes of unusually high orders.