Research Of Absorption Principles And Structures Of Electromagnetic Metamaterial Based On Fano Resonance

Electromagnetic wave absorption material is a kind of material which can absorb the electromagnetic wave in a certain frequency band or a few bands,it can achieve information selection,information concealment,electromagnetic interference and other functions through the electromagnetic absorption,has a significant application value in the stealth coating,biosensor and solar photovoltaic cells and other fields.However,the traditional absorption materials have a lot of defects,such as low absorption rate,single absorption band,strong dependence on the material bulky and so on.Recently,a perfect absorber based on artificial electromagnetic metamaterials has overcome the limitations of traditional absorbing materials,with appropriate parameters designing,the metamaterial absorber can achieve perfect absorption,multi-band absorption,and the device in mini size is suitable for integrating.The principles and structure of electromagnetic metamaterial absorber based on Fano resonance are studied in this paper which carried out under the support of the national natural fund project: "Research on Infrared Polarization Control Mechanism Based on Metamaterials"(No: 61575032).The main work of this paper is as follows:Firstly,we deeply study the principle of electromagnetic wave absorption and the Fano resonance,in view of the shortcomings of traditional absorption methods,the working principle of electromagnetic metamaterials and the related theoretical research are studied.At the same time,the resonance principle and resonance characteristics of Fano are studied from the generation mechanism.The research results show that it is feasible to apply Fano resonance to perfect absorption device.Secondly,based on the deep analysis of the existing absorptive devices,we propose a new theory of the electromagnetic metamaterial absorber based on Fano resonance;based on this principle,an absorber based on Fano resonance is designed.The absorption in the structure is produced by the Fano resonance which arose with the interaction of the double elliptic structure with the incident light.In this paper,the electric field distribution of the device with the excitation of the incident wave is analyzed.The simulation results show that the device not only has high absorbance multi-band absorption,small volume and easy to integrate,but also has good application in polarization filter.Finally,the structure is optimized on the basis of the double elliptical column structure.By introducing the asymmetry in the structure,a Fano resonance is introduced to achieve the purpose of increasing the absorption band which absorbance can achieve nearly 100%.Based on the optimization of the structure,the influence of the structural parameters of the device on the working performance is further studied.The effects on the performance of the absorber of five structural parameters,unit cycle,ellipse long axis,elliptical short axis,elliptical pitch and rotation angle and the maximum absorption rate were studied by means of numerical simulation.According to the characteristics of the device,the application of the device in polarization filter and refractive index sensor is analyzed.The results show that the Fano resonance generated by the structural asymmetry has good performance in the polarization filter performance and the refractive index sensitivity.In addition,the asymmetric structure achieved high refractive index sensitivity in the visible light band by optimizing the structural parameters is also shown in this paper.