Mechanism Analysis And Design Of Infrared Absorbing Metamaterial Based On Surface Plasma Polaritons

Infrared metamaterial absorbers have very broad development prospects and great potential application in thermal radiation control, sensing and detection. In recent years,infrared metamaterial absorbers are rapidly becoming a hot research topic in the field of artificial electromagnetic structure materials. With the continuous improvement of the frequency of electromagnetic wave,On the one hand, infrared metamaterial absorbers show a new electromagnetic characteristic and a broad research space; on the other hand,infrared metamaterial absorbers are accompanied by more complex and difficult electromagnetic phenomena and impact the existing theory of electromagnetic coupling analysis and means. In this paper, we fully understand the importance of electromagnetic coupling analysis, and try to introduce a more effective and convenient method of electromagnetic coupling analysisIn this paper, based on the traditional metal(with grating )-dielectric-metal sandwich ultra infrared absorbing material model, three more complex electromagnetic resonances, magnetic resonance, standing waves and surface plasmon polaritons, are introduced and the mutual coupling between the three resonances are realized. The Floquet model is introduced through the Rigorous Coupled Wave Analysis method and the relationship between Floquet modes and the three resonances are established. Then,the electromagnetic coupling analysis method based on Floquet mode analysis and electromagnetic boundary condition is proposed and the coupling phenomenon between the standing wave and the surface plasmon polaritons is explained successfully. In this paper, based on the analysis of Floquet model, we can reasonably adjust the excitation conditions of the standing wave and the excitation wavelength of the magnetic resonance, so as to realize the broadband absorption effect of different infrared bands.The main work of this paper is as follows:(1) We have established the relationship between Floquet modes and the three resonances. For the TM0 standing waves, its energy is only concentrated on the 0 th Floquet mode . For the TMi standing waves, its energy is concentrated on the i th Floquet mode or . There are standing waves in two direction. For the TMi surface plasmon polaritons, its energy is concentrated on the i th Floquet mode .(2) We have found and explained the equivalent dielectric phenomena in the sandwich type infrared absorbing metamaterials. If the thickness of the dielectric layer is smaller than , then the enhanced will distribute into the air. Therefore, the SPPs is not simply excited on the lower dielectric-Al interface, but on an equivalent dielectric-metal interface. The equivalent dielectric layer consists of the whole dielectric layer and an air layer with a certain thickness determined by the electric field distribution in the air.(3) We have proposed a new approach based on the boundary conditions and Floquet modes to reveal the coupling mechanism between standing waves and surface plasmon polaritons and the energy transfer between them. We have also established an identity to quantify the energy transferred between them and the contradictory relationship between the strengthened absorption by surface plasmon polaritons and the transferred energy. Eventually the traditional restriction about that surface plasmon polartitons excitation wavelength has nothing to do with the dielectric material thickness was broken.(4) We haved presented an infrared absorbing metamaterial with double dielectric materials. The thickness of the dielectric layer is greatly reduced by adjusting the shape of the metal grating. At the same time, the introduction of dual media materials reduces the electromagnetic reflection of the air-medium surface and the excitation wavelength of the magnetic resonance. We have finally realized the coupling of magnetic resonance,standing wave and surface plasmon polaritons with reasonable material and size and achieved a broadband absorption in the 5μm-8μm and 8μm-14μm. respectively.In this paper, the coupling analysis method based on Floquet model is expected to greatly simplify and quantify the analysis of complex electromagnetic phenomena. The proposed infrared absorption of ultra-material materials with double dielectric materials is with simple structure, easy to produce and excellent broadband absorbing effect,which provides a better material for the subsequent thermal radiation control research.