Design of broadband graphene-metamaterial absorbers for permittivity sensing at mid-infrared regions

Hailong Huang,Hongjian Li,Wenke Xie,Hui Xia,Zhibo Guo,Ding Xie

doi:10.1038/s41598-018-22536-x

Hailong Huang, Hongjian Li + Show 4 more

Open Access

https://doi.org/10.1038/s41598-018-22536-x

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Journal: Scientific Reports	Publication Date: Mar 8, 2018
Citations: 74	License type: open-access

Affiliation: Central South University

Abstract

In this paper, a tunable broadband metamaterial absorber (MA) based on graphene is investigated theoretically and numerically at mid-infrared regions. Compared with the previously reported multiband graphene-based MAs, a broad bandwidth of 11.7 THz with the absorption over 90% is obtained in the proposed MA, which is composed of a Jerusalem cross (JC) metal encrusting into the slot graphene layer in the top layer. The results show that the origin of broadband absorption is caused by coupling effect between metal and graphene, and this effect is explained by the two-mode waveguide coupling theory. The tunability of MA is achieved via changing the external gate voltage to modify the Fermi energy of graphene. Further results show that the proposed MA can be used as the permittivity sensor with a high absorption. This work indicates that the proposed MA has the potential applications with respect to sensors and infrared absorbers.

Highlights

Metamaterial absorbers (MAs), a new type of artificial materials, have been widely investigated in recent years due to the electromagnetic (EM) properties which are absent in traditional materials[1,2]
In order to interpret the absorption mechanism of the MA, we investigate the electric field distributions for normal incidence at 84.2 THz and 91.2 THz
In Fig. 4(a1) and (a2), for TE polarized wave, it can be seen that the electric field mainly distributes on the edge of the Jerusalem cross (JC) metal and slot graphene layer, which means that the electric field is resonantly localized and concentrated at some part of the MA at low resonance point

Summary

Structure and Simulation

A JC metal is employed to be embedded into this slot This layer is used to induce the broadband high absorption. Zt2 is the surface impedance of dielectric spacer. The input surface impedance of dielectric spacer Z1 can be shown as follows: Z1 = jZt2 tan(kmt). To investigate the absorption property, the expression of the sheet impedance of the graphene Zg and metamaterial Zm should be solved. The sheet impedance of the graphene Zg can be expressed as:

Results and Discussion

Conclusions

Author Contributions

Additional Information