Abstract
Tunable terahertz absorption in the interface between graphene and dielectric Bragg reflector (DBR) has been numerically demonstrated. The near perfect absorption mainly originates from the enhancement of the electric field owing to the excitation of the optical Tamm state (OTS) at the interface between graphene and dielectric Bragg mirror. It has been found that the absorption peak occurs at specific incident angles, which can be employed for realizing the frequency and angular absorbers. Further, we demonstrate that the position of the absorption peak can be tuned by changing the Fermi energy of graphene. Moreover, the behaviors of the near perfect absorption are strongly related to the dielectric constants and thicknesses of the surrounding dielectrics. The tunability of graphene-DBR structure absorption may help to find favorable applications for the realization of high-performance graphene optoelectronic devices.
Highlights
The electromagnetic absorber is a kind of functional device that can reduce the reflection and transmission of incident light
In this paper, we propose realizing near perfect absorption of electromagnetic waves by exciting optical Tamm state (OTS) through graphene-dielectric Bragg reflector (DBR) structure
We discuss the characteristics of reflectance and absorption in the graphene-DBR structure
Summary
The electromagnetic absorber is a kind of functional device that can reduce the reflection and transmission of incident light. The conductivity of graphene can be tuned by adjusting gate voltages or chemical doping [31, 32], which means that we can obtain different absorption peaks by changing the Fermi energy. In this paper, we propose realizing near perfect absorption of electromagnetic waves by exciting OTS through graphene-DBR structure. Owing to the excitation of OTS and the method of transfer matrix, the structure can achieve almost total absorption in the THz band. We can achieve near perfect absorption at different wavelengths by adjusting the Fermi energy of graphene, the thickness, and permittivity of the top layer. We believe that the tunable electromagnetic terahertz absorber has potential applications in thermal sensing, THz imaging, and emissivity spectrum modifiers
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