Effective surface plasmon polaritons on the metal wire with arrays of subwavelength grooves.

In this paper we explore the existence of electromagnetic surface bound modes on a perfect metal wire milled with arrays of subwavelength grooves. The surface modes are axially symmetric transverse magnetic (TM) waves and have the same polarization state with the dominant propagating surface plasmon polaritons on the real metal wires. The dispersion of the fundamental surface mode has close resemblance with the dispersion of the surface plasmon polaritons. Moreover, we note that for TM polarization this metallic structure can be equivalent to a dielectric coated metal wire with defined geometrical parameters and effective refractive index of the dielectric coating. This metallic structure is expected to have some potential applications in the optical research in microwave or THz region.