Tooth-shaped plasmonic waveguide filters with nanometeric sizes

A novel nanometeric plasmonic filter in a tooth-shaped metal-insulator-metal waveguide is proposed and demonstrated numerically. An analytic model based on the scattering matrix method is given. The result reveals that the single tooth-shaped filter has a wavelength-filtering characteristic and an ultracompact size in the length of a few hundred nanometers, compared to gratinglike surface plasmon polariton (SPP) filters. Both analytic and simulation results show that the wavelength of the trough of the transmission has linear and nonlinear relationships with the tooth depth and the tooth width, respectively. The waveguide filter could be utilized to develop ultracompact photonic filters for high integration.