The guided dispersion characteristics of the fundamental symmetric and asymmetric modes of surface waves along single- and double-negative indexed slab waveguides are investigated, and a comparative analysis made when varying the single- and double-negative permittivity and permeability. While the values of the permittivity and permeability of the slab region are varied to obtain a salient picture of the guided dispersion characteristics, identical absolute product values are used for both slab cases to facilitate a reasonable comparison. In particular, in common ranges where guided mode solutions coexist for both the single- and double-negative indexed slabs, the guided mode characteristics are similar with a lower normalized frequency regime, indicating that the sign of the material parameters has a negligible effect, whereas the characteristics become quite different as the normalized frequency increases. Some other anomalous guided dispersion properties are also discussed and compared with previously reported results.

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The light transmission through a dispersive plasmonic circular hole is numerically investigated with an emphasis on its subwavelength guidance. For a better understanding of the effect of the hole diameter on the guided dispersion characteristics, the guided modes, including both the surface plasmon polariton mode and the circular waveguide mode, are studied for several hole diameters, especially when the metal cladding has a plasmonic frequency dependency. A brief comparison is also made with the guided dispersion characteristics of a dispersive plasmonic gap [K.Y. Kim, et al., Opt. Express 14, 320–330 (2006)], which is a planar version of the present structure, and a circular waveguide with perfect electric conductor cladding. Finally, the modal behaviour of the first three TM-like principal modes with varied hole diameters is examined for the same operating mode.

In order to deri¨e closed-form expressions of Green's functions for the¨ector and scalar potentials of a horizontal magnetic dipole in a parallel-plate wa¨eguide filled with a homogeneous dielectric, an impro¨ed complex image method based on the two-le¨el approximation is considered in conjunction with the use of Prony's method. The results for the e¨aluation of the closed-form Green's functions obtained ( ) by the present method two-le¨el approximation are compared with ( ) those obtained by the pre¨ious method one-le¨el approximation . The present method is obser¨ed to gi¨e more accurate results than the pre¨ious method o¨er the wide frequency range as well as the whole spatial range.

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