Highly-confined and low-loss spoof surface plasmon polaritons structure with periodic loading of trapezoidal grooves

Xiaoyong Liu,Yijun Feng,Lei Zhu,Qiongsen Wu

doi:10.1063/1.4926770

Xiaoyong Liu, Yijun Feng + Show 2 more

Open Access

https://doi.org/10.1063/1.4926770

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Journal: AIP Advances	Publication Date: Jul 1, 2015
Citations: 45	License type: CC BY 3.0

Affiliation: University of Macau, Nanjing University

Abstract

In this paper, we propose an ultra-thin spoof surface plasmon polaritons (SPPs) structure, periodically loaded with trapezoidal grooves. Compared to the reported SPPs with rectangular grooves, the proposed SPPs structure can support the guided surface SPP wave with enlarged propagation constant, which implies an enhanced confinement of surface wave along the spoof SPPs structure. Guided-wave characteristics of the proposed SPPs structure are theoretically investigated by virtue of a numerical short-open calibration (SOC) technique. The results show that the loss of spoof SPPs is lower than that in other reported spoof SPPs structures. Experiment on prototype in microwave frequency regime is carried out which validates the theoretical findings. It is believed that the proposed structure could be scaled to THz frequencies, and is very promising in developing the miniaturized planar surface plasmonic devices and circuitry.

Highlights

Surface plasmon polaritons (SPPs) are the surface electromagnetic (EM) waves which propagate along the dielectric-metal interface at optical frequencies.[1]
The proposed ultra-thin plasmonic structure with trapezoidal grooves in periodicity is schematically shown in Fig. 1(a), in which the top and bottom widths of grooves are denoted as b and a; the depth and periodicity of the grooves are marked as h and d; the width of metal strip is indicated as w, respectively
EXPERIMENTAL VERIFICATION Since the confinement to spoof surface plasmon polaritons (SPPs) is inversely proportional to the asymptotic frequency, we can alternatively verify the characteristic of localization to spoof SPPs by calculating and measuring the cutoff frequency of transmission coefficient, S21, of the proposed spoof-SPPs structure with finite number of grooves

Summary

INTRODUCTION

When the thickness of metal structure is decreased.[15,16] Shen et al took this idea to the extreme case and proposed the ultra-thin plasmonic metamaterial which can support spoof SPPs.[17] Due to its flexible property, such ultra-thin plasmonic metamaterial paves the way of developing versatile surface-wave integrated devices or circuits at lower bands, especially, at THz region. Compared to the traditional counterpart with rectangular grooves, our research shows that the proposed spoof-SPPs structure exhibits strong localization or high confinement of SPP surface-wave at a given frequency. The propagation loss of spoof SPPs is studied by extracting its attenuation coefficient via numerical short-open calibration (SOC) technique.[24] In final, the enhanced confinement of spoof SPPs for our proposed structure is verified in experiment by the cutoff frequencies of spoof-SPPs surface wave

DISPERSION RELATION OF THE PROPOSED PLASMONIC STRUCTURE

THEORY ANALYSIS FOR THE LOSSES OF SPOOF SPPS

EXPERIMENTAL VERIFICATION

Findings

CONCLUSION