Study On Optical Properties Of Metallic Ring In Nano-metamaterial

Metamaterials are a class of artificial composite structures or material with extraordinary physical properties that natural materials do not possess.Through strict and complicated artificial design,it exhibits attractive physical properties,such as negative refraction,invisibility,electromagnetically induced transparency,perfect absorption and unidirectional reflectionless propagation and so on.The discovery of metamaterials has opened a new research direction for electromagnetic theory and provided a new idea for the material field.In this thesis,the optical properties of the metal ring nano metamaterial are studied.The main work are as follows:1?Based on the metamaterial theory,we designe a ring resonator that uses high-order magnetic plasmonic resonance to achieve ultra-narrow-band perfect absorption.Due to the ring-shape element,the system is independent of polar-ization.Research indicate that the absorption and bandwidth at eigen resonant frequency 178.76 THz are?56%and 347 nm when the thickness t of MgF2 is 60 nm,respectively.The absorption at high-order resonant frequency 424.5 THz is?1,its bandwidth only is 13 nm.Obviously,the absorption based on high-order reso-nant mode are higher than that of eigen resonant mode,while bandwidth based on high-order resonant mode are narrower than that of eigen resonant mode.Accord-ing to the reflection intensity change at a fixed resonant wavelength that is induced by a change in the refractive index of environmental medium,we calculate the figure of merit(FOM*)and sensitivity of perfect absorption peaks based on high-order magnetic plasmon resonance are 3700 and 190 nm/RIU,respectively.2.A controlled unidirectional reflectionless propagation is achieved at excep-tional point(EP)in metal ring nano metamaterial system.Due to two ring element,the system is independent of polarization.Research indicate that the reflection at wavelength 1441 nm is?0 when the distance is between two silver ring resonators is 485 nm and the incident wave is excited along +z direction.The reflection at wave-length 1387 un is?0 when s reduces to 395 nm and the incident wave is excited along-z direction.So bilateral unidirectional reflectionless propagation at different wavelengths can be manipulated by adjusting distance s.In addition,the struc-ture can act as an ultra-narrow-band perfect absorber nears EPs.The absorption exceeds 96%and Q-factor of absorption peak is?41.In summary,we achieve ultra-narrow-band perfect absorption and unidirec-tional reflectionless propagation based on the tunability of the metal ring nano metamaterials,These optical properties provide potential applications in sensors,detectors and filters.