Study On Broadband Infrared Near-perfect Absorber Based On Plasmon

The optical near-perfect absorber has made great progress in the field of plasmon metamaterials,and has corresponding applications in various wavebands from radio to optics.Among them,the mid-to-far infrared（MF-IR）region（8～14μm）is a highly transparent atmospheric window band in the electromagnetic band,which can cover the broadband of this region.High-absorption devices are used in thermal imaging technology,thermal infrared light source,emissivity coating,Photoelectric detection and bolometer have great application potential,and the Broadband Infrared Near-Perfect Absorber（BIPA）is an important technical way to realize related applications.Although the design principles of plasmon metamaterials are used to easily obtain single-band or multi-band BIPA,due to the inherent narrow bandwidth of surface plasmons,local surface plasmon resonance can be generated on the surface of nano-scale metal,So as to produce a high Q factor effect in a specific band.Therefore,it is still a big challenge to achieve near-perfect absorption of broadband infrared.Broadening the absorption bandwidth of metamaterial absorbers has become a key goal to achieve a wide range of applications.This paper has theoretically and experimentally developed an efficient BIPA for MF-IR light absorption.The absorber unit structure is two pairs of circular dielectrics placed on top of a silicon nitride/gold（Si₃N₄/Au）double-layer film structure（Si₃N₄）-metal（Au）laminated pattern super-surface composition.In the metasurface absorber unit,the Au cylinder and the bottom Au film act as a mirror,and the Si₃N₄ dielectric layer acts as a spacer for the laminated metal-dielectric material-metal（MDM）structure.The principle of broadband high absorptivity is the multi-mode resonance coupling of propagating surface plasmon resonance（PSPR）closely related to the period of metamaterials and multi-gap magnetic excimer resonance（MPR）supported by MDM cavity structures of different dielectric thicknesses.Its absorptivity is higher than 80% in the entire atmospheric window with a wavelength of 8～14μm,and can achieve near-unit high absorptivity independent of incident light polarization in a large incident angle range from 0°to 80°.The simple structure of the absorber sample is manufactured by magnetron sputtering and laser direct writing lithography technology,which provides a new way for the manufacture of low-cost,high-efficiency,compact,and wafer-level MF-IR absorbers.Compared with the traditional absorber,it has the advantages of easy manufacture,high adjustability,high integration,etc.,and has a broad application prospect.In addition,compared with the current commercial MF-IR infrared radiation source based on refractory metals,our proposed BIPA based on laminated MDM can significantly increase infrared radiation in the entire 8～14μm atmospheric window band.Therefore,the absorber can be applied to high-efficiency infrared radiation light sources,and it is expected to be used in the field of infrared imaging sensors manufactured using CMOS compatible technology in the future.