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?14?m)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?14?m,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?14?m 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.