Investigation of High Efficiency Unidirectional Emission From Metal Coated Nanocylinder Cavities

We investigate the mode properties for metal coated nanocylinder cavities by three-dimensional finite difference time domain technique, for realizing high efficiency and unidirectional emission from the nanocavities. In a nanocavity confined by a metal layer, the metal layer provides mode confinement because it reduces the radiation loss greatly, but it also introduces a great metal dissipation loss. The compromise of the metal dissipation loss and the efficient output coupling is investigated for realizing high-output efficiency nanolasers, especially accounting the destructive interference of leakage waves. The different characteristics of the vertical radiation losses are investigated for TE and TM confined modes. Furthermore, the nanocavities connected with a thin output waveguide are proposed and numerically simulated for realizing the unidirectional emission metallic confined nanolasers.