Plasmonic filters and optical directional couplers based on wide Metal-Insulator-Metal structure.

The wide Metal-Insulator-Metal (WMIM) structure is proposed and its characteristics are analyzed numerically using finite-difference time-domain (FDTD) method. Simulations show that power can be periodically transferred between its two Metal-Insulator (MI) interfaces while power is injected asymmetrically. Novel plasmonic filters and optical directional couplers (ODCs) based on WMIM structure are proposed, which work similarly as traditional dielectric devices. Due to the simple structures without thin metal gaps, our result may provide an alternative way to realize the fabrication of nanoscale optical devices.