On the Use of Subwavelength Radial Grooves to Support Spoof Surface-Plasmon-Polariton Waves

Abstract

This letter introduces radial grooves as a feasible geometry to support spoof surface-plasmon-polariton (SPP) waves propagating along a vacuum-metallic interface. Through the analytical derivation of a dispersion relation, validated also with full-wave simulations, the ability of radial grooves to operate in the fundamental mode at the microwave regime is demonstrated. Also, results demonstrate the utility of radial geometries to decrease the depth of the grooves, in comparison with the widely used rectangular grooves, thereby providing a superior methodology for generating spoof SPPs.

Novel crest‐trough shaped spoof surface plasmon polaritons for low pass filtering applications

“…It is observed that all the grating structures are capable of confining electromagnetic waves on their surfaces with the increase in depth of groove, and the cutoff frequency clearly depends on the groove depth. Nevertheless, it is indicated that proposed structure attains lowest cutoff frequency as its deviation from the light line is highest, proving its stronger ability of confining surface wave as compared to conventional rectangular grooves . The key reason is the realization of gradual cutoff mode for proposed geometry (analogous to annular sector waveguides) showing greater attenuation of wave in contrast to rectangular groove …”

“…It can be noticed from Figures C and A that same lower level of cutoff frequency can be achieved by proposed CT SSPP with a shallower groove (6 mm) in contrast to deeper rectangular groove (11.4 mm) structure. This is the desired property of the SSPP in general, to preserve the original boundary which can be achieved by the shallow grooves . The benefit of compact plasmonic structure can be obtained by designing shallow gratings.…”

“…In this article, we propose a novel plasmonic structure with periodic crest‐trough (CT) grooves on a planar metal strip which are based on the well‐recognized family of radial grooves. Such grooves are considered ideal candidate for Spoof SPP applications at microwave regime, since their propagation modes offer gradual cutoff due to the presence of radial coordinate and can efficiently isolate the spatial propagating sectors from the non‐propagating ones of the waveguide . Higher attenuation in short propagation lengths is desired in SSPP case; hence, employing radial grooves enhances the mimic‐ability of real SPPs with reduced depth (shallow) grooves.…”

“…References and have already addressed this matter for the trapezoidal grooves by means of full wave simulations. In Reference , radial grooves has been demonstrated as a feasible configuration to efficiently support and confine SSPP with reduced groove depth in comparison to broadly used rectangular groove through analytical derivations. In present case, we consider rectangular coordinates and cover different grooves geometries (with the same dimension) corresponding to the same volumes.…”

“…Such grooves are considered ideal candidate for Spoof SPP applications at microwave regime, since their propagation modes offer gradual cutoff due to the presence of radial coordinate and can efficiently isolate the spatial propagating sectors from the non-propagating ones of the waveguide. 21,22 Higher attenuation in short propagation lengths is desired in SSPP case; hence, employing radial grooves enhances the mimic-ability of real SPPs with reduced depth (shallow) grooves. References 23 and 24 have already addressed this matter for the trapezoidal grooves by means of full wave simulations.…”