The Design Of Optical Metamaterial Unit And The Study Of Its Properties

In recent years, left-handed metamaterials (LHMs) have attracted extensiveattention and studies in the fields of electromagnetism, materials science, solidphysics and optics because of their extraordinary electromagnetic properties. Theappearance of LHMs breaks the traditionally physical concept, and becomes apioneering topic of international electromagnetism. Compared with natural materials,LHMs possess many electromagnetic properties violating routine ideas, such asnegative refractive index, backward wave property, reversal Doppler effect, reversalGoos-H nchen shift, reversal Cherenkov radiation and so on. There exist a largenumber of interesting and potential applications for the design of microwave andphotonic devices, such as resonant apparatus, absorber, filter, power couplinginstrument, electromagnetic inducement, invisible cloak, perfect lens, antennae and soon.In this dissertation, we have designed a three-dimensional (3D) isotropic LHMbased on the original meta-atoms as metallic rod and split ring resonator (SRR), andstudied their left-handed properties at microwave and visible frequencies by adjustingits structural parameters. In order to depress the losses, the3D metamaterial structurewas transferred from homogeneously metallic structure into topological metamaterialstructure which was composed of interiorly insulative state and exteriorly metallicstate, and its resonant characteristics were numerically studied in the visible range.Later on, we demonstrate the fabrication of visible NIM by template-assisted andself-assembled electrochemical deposition, producing a three-layered structureconsisting of two apertured metal films asymmetrically on the opposite sides of adielectric layer. Its visible properties have been numerically and experimentallystudied. Finally a novel double-fishnet metamaterial with the broad-band negativeindex was proposed and studied numerically. The main contents of the dissertation arelisted as follows:1. A U-shaped ring was designed based on the basic metamaterial model of SRR,the organization of several U-shaped rings gave birth to a two-dimensional (2D)isotropic metamaterial, and further it was turned into a3D isotropic metamaterial.According to the effective medium theory, the negative refractive indexes of the2D and3D metamaterials were retrieved in the microwave band. The concept ofdomain-structured metamaterial was proposed by analyzing their resonant currents distribution.2. The operating wavelength of this3D LHM was lifted to visible region bydwindling and adjusting its geometrically structural parameters with Drude model.According to the characteristics of its resonant currents, the3D structure wasviewed as a cluster-structured metamaterial composed of the unit atoms ofU-shaped rings. In the light of the discrepant size resulting from the fabricationerror, the effects of the occurrence of some cluster structures with different sizein the periodic array on the electromagnetic properties were studied. Also thelarge-sized cluster structure was dwindled to sub-wavelength-sized structure, itsresonant properties was numerically studied both in red-light and blue-lightwavelengths by appropriately adjusting its structural parameters.3. In order to depress the large losses in the homogeneously metallic structures,referring to the low-loss structure of topological insulator, we transferred thehomogeneously metallic3D metamaterial into topological metamaterialcomposed of interiorly insulative state and exteriorly metallic state. The effects ofthe permittivity of interior insulator and the thickness of exterior metal on theresonant characteristics were numerically discussed, which could providetheoretic grounds and principle for the design of topological metamaterialstructures. Also the influences of the appearance of some cluster structures withdifferent size in the periodic array on the resonant properties were studied.4. A kind of asymmetrical Ag-PVA-Ag metamaterial structure was proposed, ifkeeping the disalignment in a moderate range, its negative-index properties atvisible frequencies has been numerically demonstrated. In view of the numericalanalysis, we fabricated two groups of samples with different sizes operating at thered-and green-light wavelengths, respectively. RhB as a dopant material wasincorporated into the PVA dielectric layer in order to meliorate the properties ofthe PVA layer, and its effects was investigated through control experiments. Soeach group includes two types of samples, namely, those with and without RhB.5. The amplitudes and phases of transmission and reflection of the green-lightresonant sample without RhB are measured to retrieve its effectiveelectromagnetic parameters according to the effective medium theory. Thenegative refractive index was realized at green-light wavelengths, which verifiedthe resonant characteristics and the reliability of fabrication.6. Two control experiments for the two groups of samples were completed: the transmission measurements in the range of400-800nm wavelengths and themonochromatic light transmission versus distance away from the flat samples.Comparing with the results of the sample with and without RhB in the twoexperiments, it was found that the sample with RhB exhibited more obvioustransmission behaviors. Two kinds of possible explanation for the function ofRhB in the metamaterial structure were proposed.7. The traditional double-fishnet metamaterial structure with the same sized mesheswas changed to a new model with16kinds of different sized meshes, and it couldrealize the negative refractive index in the broad band of red-, orange-, yellow-,and green-light wavelengths. Later on, based on this new kind of double-fishnetstructure, a multi-band visible absorbers composed of “simler mesh-PVA-silvermesh-silver-PVA-silver film” was designed and numerically studied.