Excitation of highly concentrated spoof surface plasmon polaritons based on LC-resonance theory

In this article, a novel method based on LC-resonance theory has been proposed, for the excitation of highly concentrated spoof surface plasmon polaritons (SSPPs). For this purpose, a new n-shape groove is proposed to apply LC-resonator idea in a different but an efficient way. A pi-shape groove is formed by developing a seamless connection between pi-type particles and the grooves of the spoof SPP waveguide such that they behave as one unit. The proposed method based on LC-resonance theory has never been studied before in order to excite highly concentrated spoof SPPs. Two configurations of pi-shape groove have been used, so-called asymmetric and symmetric ones. In both configurations, spoof SPPs demonstrate excellent boundedness of field as compared to traditional spoof SPP waveguide. Excitation of highly concentrated spoof SPPs is achieved in the proposed pi-shape spoof SPP waveguide due to the continuation of pi-type particles with the rectangular grooves of the SPP waveguide, where SPPs are confined the most. In other words, field stays more inside the pi-shape grooves of SPP waveguide which results in excellent excitation of highly concentrated SSPPs. This novel pi-shape groove introduces larger capacitance resulting in higher LC-coupling which comes up with greater and tighter field confinement of SSPPs. More precisely, a pi-shape groove is designed in such a way that it offers more space, greater equivalent capacitance in LC-resonant circuit and higher LC-coupling which excites highly concentrated spoof SPPs. Furthermore, excellent control on bandwidth has been demonstrated by varying the width of the pi-shape groove without changing the groove depth on ultra-thin periodic corrugated metallic strip. The simulation and measurement results illustrate the excellent verification of above made predictions. The proposed waveguide will be a very healthy step toward the advancement of integrated plasmonic devices in microwave and terahertz regimes.