Fanolike resonance in light transmission through a silver film perforated with an array of SRR-shaped apertures

We study theoretically light transmission through a silver film perforated with an array of split-ring resonator (SRR) shaped apertures. An asymmetric lineshape, which is characteristic of the Fano resonance, has been found in a narrow frequency range of the spectrum. The effect can be attributed to the interference between propagating surface plasmon polaritons (SPPs) on the silver film and magnetic plasmon polaritons (MPPs) associated with the SRR-shaped apertures. An anticrossing behavior of the resonance positions has also been observed in the transmission spectra, demonstrating the strong coupling of the SPPs with the MPPs. Due to the steep dispersion of the Fano resonance profile, the plasmonic nanostructure proposed could find important applications in sensors, switching, and nonlinear and slow-light devices.