Design And Preparation Of High-performance Metamaterial Absorber For Thermal Infrared Atmospheric Window

Metamaterials,a typical artificial composite materials,have extraordinary physical properties compared with natural materials.Some strange electromagnetic properties can be obtained by reasonably designing the structure and size of existing substances in nature.The design of metamaterials is flexible and has the advantages of thin thickness and small volume.There are many researches about metamaterial absorbers applied in erahertz and infrared bands.As we know,the band from 8 ?m to14 ?m is the thermal infrared atmospheric window.Absorbers in this band play an important role in many fields,such as,infrared detection technology,infrared stealth,thermal photovoltaics,solar cells,biosensor,and so on.However,how to design a perfect absorber with multiple absorption bands,simple structure and easy processing is still a challenge.This thesis mainly studies the high-performance broadband metamaterial absorber in the thermal infrared atmospheric transparent window.The contents are as follows:Firstly,Theoretical simulation: the design of thermal infrared high-performance broadband metamaterial absorber is carried out.This thesis presents a design of ultra-broadband metamaterial absorber,which is composed of germanium zinc sulfide chromium zinc sulfide disk periodic array and refractory metal chromium(room temperature melting point 1907 ?).The commercial electromagnetic simulation software CST is used for numerical simulation,and the optimal geometric parameters are obtained through optimization.The proposed structure has an average absorption rate as high as 99.1% in the infrared transparent window of the atmosphere,and achieves near-perfect absorption.In TE polarization,the absorption rate is up to 99.1%in the wavelength range from 8 ?m to 13 ?m.Under TM polarization,the average absorption rate is 97.1% in the range of 7 ?m to 15 ?m.When the oblique incidence angle increases to 60 degrees,the absorption is still very high.These results show that the proposed absorber has polarization independent and incident angle insensitive absorption characteristics.The absorber has a simple structure and is easy to process.It can be mass-produced at a low cost through existing technologies such as nano lithography.Secondly,try to prepare a broadband infrared multilayer film absorber with adjustable structural color.Experimental partner Li Si-rui created and simulated an absorber with multilayer structure based on sub /[Nichrome/ Ge/ Nichrome/ Zn S/ Ge/Zn S]/ Air.The structure not only has excellent broadband absorption performance in the band of the atmospheric transparent window,but also changes the thickness of the top film within a certain range to adjust the surface color of the structure and maintain its infrared absorption performance.In this study,magnetron sputtering technology was selected to prepare multilayer film structure,to be specific,DC magnetron sputtering prepares nickel-chromium(Ni-Cr)alloy film,while radio frequency magnetron sputtering prepares germanium(Ge)film and zinc-sulfide(Zn S)film.In the end,the phase analysis was carried out by XRD,the thickness was measured by step profiler.