Design For Plasmonic Metamaterial Absorbers And Investigation On Their Properties

Metamaterials,as a class of novel materials based on artificially-engineered sub-wavelength nanostructures and microstructures,have attracted expanding attention over the past years.The electromagnetic characters of traditional materials mainly hinge on the atomic or molecular properties.However,the electromagnetic properties of metamaterials can be manipulated by controlling the distribution,geometrical parameters and materials of the designer periodic structures,which enables a lot of exotic properties and makes metamaterials promising for optical manipulation,energy engineering,biomedicine and some other applications.Thanks to the advancements of nanofabrication techniques and theoretical analyzing methods,the investigation on light harvesting devices based on plasmonic metamaterials has made great progress over the past decade.Metamaterial absorbers have exhibited great potential for being utilized in solar energy harvesting,imaging,sensing and optoelectronic devices.In this study,we introduce the development of plasmonics and metamaterials.We investigate the ultra-broadband perfect absorbers based on metal-insulator-metal（MIM）and all-metal configurations,and illuminate the physical mechanisms behind their performances.In addition,we analyze the materials and structures which are suitable to generate broadband optical absorption.On the other hand,we introduce metamaterial absorbers with narrowband optical response,which could be viable option for sensing devices in fields including biology,industry,chemistry,and so on.Furthermore,focusing on the realistic application,we also discuss the strategies for low-cost and scalable designs.We proposed a metamaterial which is based on cross-shaped titanium（Ti）resonators and obtained a broad absorption band up to 2100 nm.Within the wavelength range of 400-2500 nm,the average absorption reaches 93.8%.Moreover,the optical responses exhibit low sensitivity to the polarization angle and incident angle of waves,which enables high efficiency when this absorber is utilized in real-world applications.We report a scheme for ultra-broadband wave absorption and efficient solar energy harvesting.Using a metamaterial composed of the topmost two-dimensional titanium（Ti）gratings,the sandwiched aluminium oxide（Al₂O₃）film,and the bottom opaque Ti plate,we achieved high-efficiency light absorption at the wavelength range of 200-2980 nm.The bandwidth reaches 2700 nm and the averaged efficiency is up to97.85%,suggesting superior capability to harness solar energy.Past schemes for metamaterial absorber have relied on sophisticated configuration.In this design,the structure is simple but it can provide remarkable absorption efficiency,however,this work is free of complex fabrication and has a combination of advantages such as high absorption efficiency and high thermal robustness,indicating a promising prospect for solar thermophotovoltaic systems.This work features simple configuration and superb properties and it provides a new way to design high-performance thermophotovoltaic elements.