Figure 1

(a) A two-dimensional corrugated PEC cylinder (invariant along the $z$ direction) with the inner and outer radii $r$ and $R$, periodicity $d$, and groove width $a$. The refractive index in the grooves is denoted $n_g$. (b) In the effective medium approximation the geometry displayed in (a) behaves as an inhomogeneous and anisotropic layer of thickness $(R-r)$ wrapped around a PEC cylinder of radius $r$.Reuse & Permissions

Figure 2

(a) Complex resonance frequencies found using the modal expansion technique and (b) the numerically computed SCS (solid line) for a textured PEC cylinder with $r=0.33R$, $N=60$, $a=0.4d$, $n_g=1$, and ${\omega }_{a}R=0.89\pi c$. The dashed line in (b) corresponds to the calculation in the metamaterial approximation (see main text). The inset shows the dispersion relation of the corresponding spoof SPP. (c) SCS for a Drude metal cylinder of radius $R$ with the same ${\omega }_{a}R$-value as in (b). The inset shows the dispersion relation for Drude metal SPPs. The right panels display the absolute $H$ field at the hexa-, octo-, and decapole resonances for the two systems. The color scales are chosen so that the field outside the textured cylinder is emphasized.Reuse & Permissions

Figure 3

SCS for a subwavelength corrugated PEC cylinder with $r=0.4R$, $N=30$, $a=0.8d$, $n_g=8$, and ${\omega }_{a}R=0.12\pi c$. The dashed line corresponds to the metamaterial approximation. The insets show the corresponding dispersion relation for the spoof SPP and magnetic field amplitude plots at the di- and quadrupole resonances. The color scales are chosen so that the field outside the textured cylinder is emphasized.Reuse & Permissions

Figure 4

(a) Two three-dimensional corrugated PEC cylinders with height $L$ and separation $s$. The incident plane wave is $x$ polarized and propagating along the $z$ direction. (b) Electric field enhancement in the center of the gap as a function of the separation for corrugated PEC cylinders with $r=0.4R$, $N=30$, $n_g=8$, $L=R$ and different values of $a/d$. The field enhancement is evaluated at the dipole resonance frequency of the combined system. The line with circular dots corresponds to PEC cylinders without corrugation. The inset shows the field enhancement in the $xy$ plane for $a/d=0.1$ at two different separations.Reuse & Permissions