Nanoscale Core-Shell Hyperbolic Metamaterial for Ultralow Threshold Laser Action*

We develop the nanoscale core-shell hyperbolic metamaterial (HMM) possessing a remarkably coupling effect in between the multishell components, which is due to the formation of higher density of states and longer time of collective oscillations of the electrons than the plasmonic-based pure metal nanoparticles. Subsequently, a giant localized electromagnetic wave of surface plasmon resonance is formed at the surface causing the pronounced out-coupling effect. The nanoscale core-shell HMM confines the energy well without being decayed, reducing the propagation loss and then achieving the stimulated emission (e.g., random lasing action by dye molecule) with an ultralow lasing threshold (~30 μJ/cm²). We believe that the nanoscale core-shell HMM paves a way to enlarge the development of applications, such as highly optoelectronic conversion efficiency of solar cells, great power extraction of light emitting diodes and wide spectra photodetectors.