Collective spontaneous emission and strong coupling in semiconductor hyperbolic metamaterials

Hyperbolic metamaterials (HMM) have found applications in imaging, thermal emission control, subwavelength waveguiding and single photon emission. In this paper, it is shown that unique HMM modes, normally evanescent in conventional materials, can lead to novel collective emission and absorption effects. A semiconductor based hyperbolic metamaterial system is proposed, which shows strong coupling with intersubband transitions (ISBTs) of embedded quantum wells.The predicted effect can be verified by angle-resolved-mid-IR-spectroscopy and shows vacuum Rabi splitting energies approaching the ultra-strong coupling limit.