Refractive Index-Based Terahertz Sensor Using Graphene for Material Characterization.

Aruna Veeraselvam,Ram Kumar Krishnan,Gulam Nabi Alsath Mohammed,Kirubaveni Savarimuthu,Jaume Anguera,Jessica Constance Paul

doi:10.3390/s21238151

Aruna Veeraselvam, Ram Kumar Krishnan + Show 4 more

Open Access

https://doi.org/10.3390/s21238151

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Abstract

In this paper, a graphene-based THz metamaterial has been designed and characterized for use in sensing various refractive index profiles. The proposed single-band THz sensor was constructed using a graphene-metal hybridized periodic metamaterial wherein the unit cell had a footprint of 1.395λeff × 1.395λeff and resonated at 4.4754 THz. The realized peak absorption was 98.88% at 4.4754 THz. The sensitivity of the proposed metamaterial sensor was estimated using the absorption characteristics of the unit cell. The performance of the sensor was analyzed under two different categories, viz. the random dielectric loading and chemical analytes, based on the refractive index. The proposed THz sensor offered a peak sensitivity of 22.75 GHz/Refractive Index Unit (RIU) for the various sample loadings. In addition, the effect of the sample thickness on the sensor performance was analyzed and the results were presented. From the results, it can be inferred that the proposed metamaterial THz sensor that was based on a refractive index is suitable for THz sensing applications.

Highlights

Terahertz (THz) radiation lies between the microwave and infrared frequencies
A graphene-based THz metamaterial sensor was designed and characterized for various materials based on their refractive indices
The THz sensor consisted of a periodic resonator structure that was made of graphene, which was chosen for its chemical potential tuning characteristics

Summary

Introduction

Terahertz (THz) radiation lies between the microwave and infrared frequencies. The term THz signifies a trillion cycles per second. In [8], the authors had designed an ultra-sensitive centrosymmetric double F-shaped metal resonator, using Teflon as the dielectric material, which operated at 5.92 THz. A tri-band metamaterial absorber was presented in [9]. The THz sensor was developed using a metamaterial which incorporated graphene as the conducting material. It was inferred from the data that are shown in this figure that the transmittance and reflection were minimal, with a high absorptivity of 98.88% at 4.4754 THz. In addition to this, the accuracy of the simulation was verified by repeating the designs that were proposed in [24,25].

Influence of External Bias

Effect of Varying Refractive Indices

Conclusions