Mid-Infrared Sensor Based on Dirac Semimetal Coupling Structure.

Yuxiao Zou,Ying Liu,Guofeng Song

doi:10.3390/s22062116

Abstract

A multilayer structure based on Dirac semimetals is investigated, where long-range surface plasmon resonance (LRSPR) of a dielectric layer/Dirac semimetal/dielectric layer are coupled with surface plasmon polaritons (SPPs) on graphene to substantially improve the Goos–Hänchen (GH) shift of Dirac semimetals in the mid-infrared band. This has important implications for the study of mid-infrared sensors. We studied the reflection coefficient and phase of this multilayer structure using a generalized transport matrix. We established that subtle changes in the refractive index of the sensing medium and the Fermi energy of the Dirac semimetal significantly affected the GH shift. Our numerical simulations show that the sensitivity of the coupling structure is more than , which can be used as a potential new sensor application. The novelty of this work is the design of a tunable, highly sensitive, and simple structured mid-infrared sensor that takes advantage of the excellent properties of Dirac semimetals.

Highlights

Mid-Infrared Sensor Based on DiracIn condensed matter physics, topological materials have received much research interest because of their ability to contain relativistic fermions with low-energy excitations [1–4].Dirac semimetals (DSMs) are a type of topological material, famous for their topologically protected linear dispersive energy bands
Numerous angle-resolved photoemission spectroscopy and scanning tunneling microscope experiments have confirmed the existence of conical features in the energy band structure [10–12], giving rise to a large number of subsequent theoretical and experimental follow-ups that have enriched the understanding of DSMs
We proposed a coupling structure that can greatly enhance GH displacement

Summary

Introduction

Topological materials have received much research interest because of their ability to contain relativistic fermions with low-energy excitations [1–4]. Dirac systems, where the graphene energy band crossings are susceptible to perturbation, the system perturbation can only slightly move the three-dimensional (3D) Dirac cone of the DSM without eliminating it, which is quite robust [5] This unique energy band structure endows the DSM with distinctive properties that make it suitable for optoelectronic applications [6–9]. In the mid-infrared to terahertz band, DSM and graphene have a dielectric constant below zero, which can excite surface plasmon resonance (SPR) with less loss than conventional metals (e.g., Ag and Au) and is expected to be an excellent candidate for SPR [20,21]. GH shift of this coupled structure in the mid-infrared band was studied based on the. By the thickness of GH the shift of this coupled structure in the mid-infrared band was studied based on the generalized coupling layer, thickness of the Dirac semimetal, and Fermi energy. Index of the sensing medium on the GH effect, showing excellent sensing performance

Theoretical Model and Method

Results

Variation

Conclusions