Fabry-Perot surface plasmon polaritons in metal-dielectric gratings

We investigate surface plasmon polaritons of Fabry-Perot type in periodic metal-dieleetric gratings. They originate in addition to conventional Bloch plasmons only if the slit walls are covered with metal. The analytical models for both vertical and horizontal Fabry-Perot plasmons are developed and they demonstrate qualitative agreement with results of numerical simulations. The corresponding resonance wavelengths are shown to be very sensitive to metal walls thickness.