A Novel Broadband Band-pass Filter Based on Spoof Surface Plasmon Polaritons.

Lei Zhao,Jiandong Li,Xin Zhang,Jun Wang,Hai Su,Xiaopeng Shen,Wenhua Yu

doi:10.1038/srep36069

Abstract

In this paper, we present a novel broadband bandpass filter based on spoof surface plasmon polaritons (SSPPs) in the microwave frequency band. The proposed bandpass filter includes three parts: (1) coplanar waveguide (CPW); (2) matching transition; and (3) coupled structure that is an asymmetric coupled filter constructed by five grooved strips. The proposed bandpass filter realizes excellent low loss performance from 7 to 10 GHz, in which its insertion loss is around 1.5 dB in the same frequency band. Meanwhile, this filter has a good band stop characteristic from 3 to 7 GHz. A simple but accurate transmission line model was proposed to evaluate the proposed broadband SSPPs filter. The measured data, simulated results and the results obtained from the transmission line model have shown a very good agreement. The proposed planar broadband filter plays an important role for filtering surface plasmon polaritons (SPPs) waves in plasmonic circuits and systems.

Highlights

Surface plasmon polaritons (SPPs) are highly localized surface waves in the optical frequency region, which propagate parallel to the interface between air and metal and decay exponentially in the vertical direction, since the metal has the similar property to plasma with a negative permittivity[1,2]
As the plasmonic metamaterials are advancing at a rapid pace, they are considered to be a promising candidate in the practical applications[16,17,18,19,20,21,22]
Two transition sections are designed to obtain the smooth conversion between the coplanar waveguide (CPW) and the spoof SPPs (SSPPs) filter, which can extract the transmitted SSPPs wave from the traditional CPW

Summary

Introduction

Surface plasmon polaritons (SPPs) are highly localized surface waves in the optical frequency region, which propagate parallel to the interface between air and metal and decay exponentially in the vertical direction, since the metal has the similar property to plasma with a negative permittivity[1,2]. Plasmonic metamaterials have been proposed to produce the so-called spoof SPPs (SSPPs)[8,9,10,11,12,13,14,15], which can produce highly confined surface electromagnetic (EM) wave at the lower frequencies. Thereafter, more efforts are still towards to design a bandpass filter with a wide stopband that is highly demanded in practical applications for effective suppression of the undesired noise signal. Model was first proposed to evaluate the transmission and reflection properties of the proposed filter Using this compact structure, the proposed SSPPs filter with a low loss and good transmission in the pass band has the absolute advantages in the design of the plasmonic integrated circuits in both microwave and terahertz frequency bands

Methods

Results

Conclusion