Ultra-wideband filtering of spoof surface plasmon polaritons using deep subwavelength planar structures.

Ming Zhe Hu,Jun Feng Liu,Tie Jun Cui,Zhao Ding,Hao Chi Zhang,Wen Xuan Tang,Jia Yuan Yin

doi:10.1038/srep37605

Abstract

Novel ultra-wideband filtering of spoof surface plasmon polaritons (SPPs) is proposed in the microwave frequency using deep subwavelength planar structures printed on thin and flexible dielectric substrate. The proposed planar SPPs waveguide is composed of two mirror-oriented metallic corrugated strips, which are further decorated with parallel-arranged slots in the main corrugated strips. This compound structure provides deep subwavelength field confinement as well as flexible parameters when employed as a plasmonic waveguide, which is potential to construct miniaturization. Using momentum and impedance matching technology, we achieve a smooth conversion between the proposed SPPs waveguide and the conventional transmission line. To verify the validity of the design, we fabricate a spoof SPPs filter, and the measured results illustrate excellent performance, in which the reflection coefficient is less than −10 dB within the −3 dB passband from 1.21 GHz to 7.21 GHz with the smallest insertion loss of 1.23 dB at 2.21 GHz, having very good agreements with numerical simulations. The ultra-wideband filter with low insertion loss and high transmission efficiency possesses great potential in modern communication systems.

Highlights

In this paper, we firstly propose a novel structure for spoof SPPs at microwave frequencies
In order to reach a perfect momentum matching between the spoof SPPs waveguide and the signal input port, where a traditional co-planar waveguide (CPW) working in quasi TEM mode is employed, a transition section with gradient slots and flaring ground is designed for high-efficiency conversion
Numerical simulations and experimental results show that the presented plasmonic waveguide owns high efficiency filtering of spoof SPPs in ultra-wide frequency band, which builds a solid avenue for large-scale plasmonic integrated circuits in microwave and terahertz devices

Summary

Introduction

We firstly propose a novel structure for spoof SPPs at microwave frequencies. We design and fabricate an ultra-wideband filter with low reflection and high transmission coefficient for SPPs waves. The spoof SPPs waveguide is composed of mirror-oriented corrugated metallic strips, in which compound slot geometry is further designed. In order to reach a perfect momentum matching between the spoof SPPs waveguide and the signal input port, where a traditional co-planar waveguide (CPW) working in quasi TEM mode is employed, a transition section with gradient slots and flaring ground is designed for high-efficiency conversion. Numerical simulations and experimental results show that the presented plasmonic waveguide owns high efficiency filtering of spoof SPPs in ultra-wide frequency band, which builds a solid avenue for large-scale plasmonic integrated circuits in microwave and terahertz devices

Methods

Results

Conclusion