Design of a Reconfigurable THz Filter Based on Metamaterial Wire Resonators with Applications on Sensor Devices

João Pedro Pavia,Marco Alexandre Ribeiro,Nuno Souto

doi:10.3390/photonics7030048

João Pedro Pavia, Marco Alexandre Ribeiro + Show 1 more

Open Access

https://doi.org/10.3390/photonics7030048

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Journal: Photonics	Publication Date: Jul 10, 2020
Citations: 4	License type: CC BY 4.0

Affiliation: Instituto de Telecomunicações

Abstract

A study on the design, simulation and characterization of a reconfigurable terahertz (THz) filter, composed of two frequency-selective surfaces (FSSs) with applications on sensor devices in general and highly sensitive stress sensors, is presented in this paper. Using the developed theoretical model, we found out that by careful tuning the wire parameters, it is possible to control the filter sensitivity and also the energy transmission and reflection that passes through the structure. Numerical modelling of both the mechanical and electromagnetic components (using the elasticity equation and Maxwell’s equations, respectively) has been undertaken for two types of the device assemblies based on different thermoplastic polymers transparent to the THz radiation, namely: high-density polyethylene (HDPE) and polytetrafluoroethylene (PTFE), operating in a THz window from 395 to 455 GHz. The numerical results allowed us to characterize the relation between the reflectance/transmittance and the amount of force required to obtain a specific frequency shift along that window. It was found that the device assembled with HDPE presents a more linear response and it is able to pass from a full transparency to almost full opacity using only its linear operating zone. Due to its characteristics, this THz filter might be an interesting solution not only for THz sensors based on reconfigurable filters but also for optical modulators for the THz domain.

Highlights

Terahertz (THz) is a rapidly emerging field in science with many potential applications but where there is an urgent need for new ways of producing sources, detectors and other devices such as filters, sensors and modulators
Knowing that high-density polyethylene (HDPE) and PTFE have different relative permittivity constants, it will be necessary to analyse the filter for both assembling cases
This work aimed to study a reconfigurable THz filter design, using frequency selective structures based on metamaterial resonators, so that it can be used in the development of sensor devices

Summary

Introduction

Terahertz (THz) is a rapidly emerging field in science with many potential applications but where there is an urgent need for new ways of producing sources, detectors and other devices such as filters, sensors and modulators. Artificial materials, such as metamaterials, play an important role in THz because they make it possible to design and manufacture very compact, sensitive and extremely selective structures surpassing the existing materials in nature [1,2]. New trends in this field report a paradigm change in which the inclusion of nanomaterials in metamaterial sensors and the use of graphene plasmon and graphene metamaterial devices and topological insulators induced THz surface are expected in the near future [1]

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