The Study On Infrared Absorption Structure Based On Surface Plasmon Resonance

The use of infrared radiation by humans has covered all aspects,from military to civilian.Various infrared detection and sensing methods have provided a lot of convenience in our lives.Infrared absorption is an important performance indicator of infrared detection and sensing devices.The performance of infrared devices is often limited by the low absorption rate and surface reflection of natural materials.It is often necessary to design unique absorption structures to obtain efficient infrared absorption.Compared with the traditional absorption structure,the surface plasmon resonance-enhanced absorption method based on the metal micro-nano structure can achieve perfect absorption of incident light within a thickness much smaller than the wavelength.Making it an ideal candidate for absorber layers for solar energy harvesting,thermal detection,and thermal radiation devices.Surface plasmons have the characteristics of near-field enhancement and tunable resonance wavelength.Using their unique dispersion properties and structural sensitivity,we can control the amplitude,polarization,and phase of light at the subwavelength scale.Using the surface plasmon response of metal micro-nano structures,we can manipulate the interaction between light and matter in more dimensions while achieving high-efficiency absorption and realizing many novel functions.This paper focuses on the plasmon response properties of subwavelength micro-nano structures to study methods and approaches to enhance infrared absorption.We propose a series of long-wave infrared broadband,multi-wavelength and polarization-selective metamaterial absorber designs and near-infrared enhanced absorption structures.The main research contents and innovative research results of this paper are as follows:1.We utilize multiple resonant mode designs to achieve long-wave infrared broadband,polarization-and incident-angle-insensitive perfect absorption.The supercell of ring resonators achieved broadband absorption by exciting multiple propagating and localized surface plasmon modes.A general strategy for combining lossy dielectric materials and metamaterial absorbers is proposed to achieve broadband absorption.We combined silicon nitride,a commonly used absorption layer material for long-wave infrared,with a metamaterial absorber structure and obtained a broadband absorption covering the LWIR by the hybrid mode of surface plasmon resonance and enhanced silicon nitride absorption.We fabricated broadband metamaterial absorber samples and tested them.2.Using the multi-mode response of a single resonator,we proposed a Ti-Si₃N₄-Ti three-layer metamaterial absorber structure to achieve perfect absorption in three bands of MWIR,LWIR and VLWIR.We utilize the coupling effect of the dimer cruciform resonator for exciting the dark-mode response that is difficult to excite the periodic structure of a single resonator and realize multi-wavelength narrow-band absorption in the mid-wave infrared.3.Based on the tangential resonator,we study the strategy of selective polarization absorption.Using cut wire resonators'polarization-sensitive surface plasmon response,we achieve long-wave infrared polarization-selective and spatially concentrated broadband absorption in a Ti-Si-Al sandwich structure.By replacing the continuous metal reflective layer with a wire pair grating,we achieved a high extinction ratio polarization-selective broadband absorption of LWIR,and the theoretical calculation shows that the extinction ratio can reach more than 1000.A polarization-sorting metamaterial is proposed to achieve polarization-selective absorption and transparency of unpolarized incident light simultaneously.Compared to previous polarization-selective absorption designs,our polarization-sorting metamaterial can achieve more than 90%energy utilization and an extinction ratio as high as 250.4.A near-infrared metasurface antireflection layer is designed to solve the problem that the high surface reflectivity of existing In P detectors limits their detection performance.Efficient trapping and near-field enhancement of incident light are achieved by utilizing the surface plasmon resonance of periodic subwavelength metal cylinder arrays.In the two target wavelengths of 1330 nm and 1550 nm,the surface reflectivity of the In P detector is reduced from 25%to less than 1%,and the absorptivity is increased by more than 20%.The optical field of the In Ga As layer is enhanced by a factor of 2 compared to the original structure.