  In this paper, tooth-shaped and multiple-teeth-shaped plasmonic filters in
the metal-insulator-metal (MIM) waveguides are demonstrated numerically. By
introducing a three-port waveguide splitter, a modified model based on the
multiple-beam-interference and the scattering matrix is given. The ransmittance
spectrum as a function of teeth width, depth, period and period number are
respectively addressed. The result shows the new structure not only performs
the filtering function as well as MIM grating-like structures, but also is of
submicrometer size for ultra-high integration and relatively easy fabrication.
