Design And Research Of Dual-band Infrared Absorber Based On Stacked MIM Structure

Metamaterial is a kind of artificial composite material with special physical properties.Through the design of its structure and composition materials and other influencing factors,it can break through the limitations of certain apparent natural laws,so as to obtain special material functions beyond the inherent properties of nature,such as,negative refractive index,stealth clothing,absorber and super lens etc.With the rapid development of micro-nano technology,related research has become a frontier interdisciplinary subject involving physics,materials science,engineering and chemistry.And metamaterials have become a hot topic in scientific research,with great application potential in communication antennas,stealth technology,electromagnetic countermeasures,infrared detection and radar etc.Uncooled infrared detection is one of the main infrared detection methods.The performance of the detector mainly depends on the absorption characteristics of the absorbing material.Generally,it can only respond to a specific wavelength band,and it is difficult to achieve a specific dual spectral response,which makes it limited in applications in certain fields.As an important research direction in the study of metamaterials,metamaterial absorbers can achieve theoretically perfect absorption of electromagnetic waves in any band by designing metal-dielectric-metal(MIM)structures.Compared with traditional absorption material,it has the advantages of thin thickness,strong absorption capacity,controllable frequency band,and designable electromagnetic parameters of materials.Therefore,designing the metamaterial absorber as the absorption material of the uncooled infrared detector provides a new idea and solution for the design of infrared detectors in the future,and has strong scientific and application value.In this paper,based on the surface plasmon theory,a metamaterial absorber that achieves high absorption in both mid-wave infrared and long-wave infrared is designed.And two mid-wave long-wave infrared metamaterial absorber models are proposed,and their absorption characteristics and implementation mechanisms are explored.The main work is summarized as follows:A dual-band absorber in mid-wave and long-wave infrared based on a stacked MIM disc structure is designed.The design uses different responses of different dielectric layers corresponding to the absorption band.The larger dielectric constant Ge achieves absorption at 9.97 μm in long-wave infrared;the smaller dielectric constant Si O2 achieves absorption at 3.89 μm in mid-wave infrared,and the absorption rates at both absorption peaks are higher than 98%.The graphic design of the medium makes the structure have good absorption modulation and dual-band broadband implementation capabilities,and through the combination of structural design,the average absorption rate in the range of mid-wave infrared 3.2 μm to 4.3 μm is 71%;the average absorption rate in long-wave infrared 8.5 μm to 11.5 μm is 88%.The structure has good stability of the incident angle,the absorber still maintains high absorption when the incident angle is as high as ± 45 °.At the same time,the heat loss and refractive index sensitivity characteristics of the structure were also studied and analyzed.A dual-band absorber based on a compound cross-shaped structure was designed to achieve a high absorption rate of 98.2% at mid-wave infrared 4.28 μm and 99.5% at long-wave infrared 8.23 μm.The absorption band of the metamaterial absorber mainly depends on the characteristics of the structure size.The small cross structure is embedded in the medium,and the surface cross structure and the embedded structure are used to realize the absorption of mid-wave and long-wave infrared respectively.The structure has good modulation ability,and the modulation of the structural feature size can realize the shift of the absorption peak.As the center-to-center distance of the embedded structure changes,interactions between the surface structure and the embedded structure,between the embedded structure and the embedded structure will occur.The polarization design of the embedded structure can realize the dual-band and bandwidth expansion of the mid-wave infrared through the center symmetrical combination.The design of the center symmetrical arrangement can realize the polarization insensitivity of the combined structure.With the increase of the refractive index of the environment,the absorption peaks of the mid-wave infrared and the long-wave infrared will be red-shifted accordingly.The structure will increase the absorption of a long-wave infrared 11.08μm caused by the waveguide when the incident angle is greater than 20°,and the absorption rate increases as the incident angle increases from 0 to 60°,and the absorption is as high as 98.4% when the incident angle is 60°.