A novel plasmonic waveguide for extraordinary field enhancement of spoof surface plasmon polaritons with low-loss feature

In this paper, a novel spoof surface plasmon polaritons (SSPPs) waveguide based on I-shaped grooves has been presented in order to achieve extraordinary field enhancement of spoof SPPs at deep subwavelength scale. These I-shaped grooves are basically the transformed version of rectangular grooves incorporated by conventional spoof SPP waveguide, made up by virtue of lateral extension on either ends of these grooves. This approach which consists of addressing the grooves shape transformation proves very fruitful to accommodate higher capacitance and therefore leading to ultrahigh field confinement of spoof SPPs by lowering resonance frequency. Compared with plasmonic waveguide with T-shaped grooves which occupies the highest confinement of spoof SPPs than the previously reported different grooves shapes [Journal of Applied Physics 122, 123301 (2017)], the extension of lower ends of the grooves facilitates us with ultra-strong field confinement of spoof SPPs with lowloss feature. The proposed spoof SPP waveguide is more compact and a low cost structure exhibiting a strong response for spoof SPPs than the T-shaped spoof SPP waveguide. As a comparison, SPP-TL with T-shaped grooves results have been presented along with newly proposed SPP-TL with I-shaped grooves. Simulation results show that highly confined spoof SPPs can be generated by embedding I-shaped grooves in spoof SPP transmission line as compared to the spoof SPP TL with T-shaped grooves. Furthermore, a parametric study is presented to show its influence on the confinement. The proposed waveguide can be helpful in developing various integrated plasmonic circuits and systems at microwave frequencies.