Transmission characteristics and applications of plasmonic slit waveguide based on metal-insulator-metal structure

The propagation characteristics of the surface plasmon waves supported inside the metal-insulator-metal (MIM) waveguide are studied. The resonance wavelengths are significantly related to the effective index of the mode in the slit and the length of the slit. Actually, the effective index is defined by the width of the slit and the relative permittivity of the metal and the insulator. When the effective index is obtained, the resonance wavelengths in the MIM waveguide can be estimated. Furthermore, a series of slot cavities, which perform as the drop waveguides, can be designed in the MIM waveguide with the positions of half of the resonance wavelengths. The resonance wavelengths can be coupled out from the corresponding slot cavities. Therefore, a plasmonic filter with multiple exports that respectively supply a specific pass band is achieved. The device can be developed as an optical demultiplexing component. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.OE.51.10.104601]