Controlling Thermal Emission By Magnetic Metasurfaces In Mid-infrared Spectrum

Thermal emission has many important applications in thermaophotovoltaic(TPV)device,radiative cooling,incandescent source.It is key to controlling the radiative wavelength of the heater,improve the coherence of the thermal emission,and enhance the thermal emission in these applications.For example,improve the efficiency of transferring the thermal energy into the electrical energy through selected spectrum of radiator and optical filter in thermophotovoltaic.Controlling the range of thermal emission spectrum lead the temperature of the radiation cooling is lower.Improving the coherence of thermal emission can get excellent incandescent source.As the development of artificial micro-structure.So far,a lot of artificial micro-structures which mainly including photonic crystal structure and metamaterials have been used to control the thermal emission.The study of these micro-structures is mainly aimed at the radiation intensity,frequency,polarization and spatial directionality of thermal emission.In this paper,we investigated the present situation of controlling thermal emission by artificial micro-structures and combined the social needs.We discussed controlling the thermal emission by metal-dielectric-metal magnetic metasurfaces.The main content consists of the following two jobsThe thermal emission characteristics of phonon are considered in the first work.As we know thermal emission generated by thermal vibration of lattice under thermal excitation.We know that the use of artificial microstructures to modify thermal radiation spectrum mainly has the contribution of both material and structure.Then we take the lead in considering the thermal emission of the material,and select the Si02 film as the object of study,and study the phonon thermal radiation at 12.5?m.The design Al-SiO2-Al magnetic metasurfaces to control the thermal emission of phonons.Through changing the structure parameter of metasurfaces,the magnetic resonance can be tuned to phonon resonance wavelength.The strong coupling between phonon and magnetic resonance result in an anti-crossing phonon-plasmons mode.The thermal emission of the new phonon-plasmons model is analyzed by the coupling of the magnetic resonance mode and the phonon of the sandwich structure.The polarization dependent characteristics and the angle radiation characteristics of the new phonon-plasmons mode are analyzed.In the second work,we selected the silicon nitride film to avoid the impact of the material to the thermal emission.We investigated the coupling effect between difference resonance modes in Al-SiN-Al magnetic metasurface structure.we know the periodic Bragg scattering exist in the metallic sandwich grating structure.The Bragg grating period is chosen so that the phonon thermal emission of the material has no effect on the thermal emission of the structure.We tune the magnetic resonance wavelength to Bragg resonance wavelength through changing the grating parameter of metasurfaces.The coupling between the magnetic resonance mode and the Bragg resonance mode in the sandwich structure,result in a both spatial and temporal coherence tiny point.In the process we take use of FDTD Solution design the parameter of structure and COMOSL to analysis eign-modes.The time-domain coupled-mode theory,the transfer matrix and coupled mode theory to analyze be used to explain the coupling effect in our two works.