Transmission through metallic array slits with perpendicular cuts

The transmission of normally incident plane wave through an array of subwavelength metallic slits modified by perpendicular cuts has been explored. The cuts in middle of slit affect the even and odd modes of slits in different manners. To the best of our knowledge, this is the first work to investigate the influence of cuts on higher modes of slit, which is quite different from that on the fundamental mode studied in previous papers. Shifting the cuts along the vertical slits, we can get two kinds of resonances, which can be excited when the cuts locate at the center of electric or magnetic antinodes. In addition, we propose a new explanation model, in which we ascribe the resonance to three reasons: the F-P cavity theory, the surface current flow, and the surface charges. Irrespective of even and odd modes, the increase in the length of current flow or decrease in ability of accumulating charges dominates when the cut lies at different locations, which corresponds to a red or blue shift of resonant wavelengths. All calculated results are well explained by our proposed model.