Based On Metamaterials Perfect Absorber Study On The Selectivity Thermal Emitter

With the rapid development of metamaterials in this century,due to its unique optical properties,it can achieve the effects and phenomena that cannot be achieved with traditional materials,and it is continuously used in various fields of science and technology.In the fields of thermo-photovoltaic(TPV),infrared thermal imaging and biomedical detection(thermotherapy),it is necessary to achieve control of thermal radiation.In recent years,the development of metamaterials perfect absorbers has provided new ideas and directions for selective thermal emitter.According to the Kirchhoff's law,the emissivity and absorption of an object are equal in thermal equilibrium.Based on this,this paper presents a near-infrared perfect absorber/thermal emitter design.In this paper,we first briefly introduce the perfect metamaterial absorber and the basic laws of thermal radiation,and then introduce Maxwell's equations and commonly used calculation methods used in electromagnetic simulation.In the design of metamaterials,we use a classical metal-dielectric-metal structure,because of the good optical properties of graphene in the near-infrared band,we introduce double-layer graphene in the design.The absorption of the designed structure was compared with the absorption of uncovered graphene structure.It was found that the introduction of graphene can enhance the plasmonic of the structure,and achieve stronger absorption of electromagnetic waves and increase the absorption of metamaterials.Through finite-difference time-domain simulation,it can be found that the structure designed in this paper achieves perfect absorption at 1800 nm.At this time,the enhanced electric field is concentrated at the interface between the upper metal and the intermediate dielectric layer,and the enhanced magnetic field is concentrated in the intermediate dielectric layer.The emissivity of the corresponding structure is close to 1,and the thermal radiation is concentrated near 1800 nm compared with the ideal black body radiation,which enables selective control of thermal radiation.And by adjusting the chemical potential of graphene,it is possible to achieve a simple tuning of the absorption rate/emissivity,as the chemical potential gradually increases,the absorption gradually decreases.In addition,by adjusting the metamaterial structure period,its working range can be extended to the entire near-infrared band,enhancing its practicality.