Experimental observation of sharp cavity plasmon resonances in dielectric-metal core-shell resonators

Abstract

We report on the experimental realization of dielectric-metal core-shell resonators with a nearly perfect metal shell layer by physically depositing metal onto the self-supporting dielectric colloids. Sharp electric and magnetic-based cavity plasmon resonances are experimentally observed, whereas increasing the metal shell thickness increases their Q-factors while narrowing their linewidths. In particular, a high Q-factor up to ∼100 with a correspondingly narrow linewidth down to ∼12 nm is experimentally obtained at a dipolar magnetic cavity plasmon resonance. Simulations and analytical Mie calculations show excellent agreements with the experimental results and demonstrate strong optical field confinement of such three-dimensional resonators.