The simulation and structure design of optical metamaterials

• Main Author: Jiao, Jiao
• Other Authors: Li, Lin
• Published: University of Manchester 2013
• Subjects: 620.1; Metamaterial
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.576848

Metamaterials are artificial materials engineered to have properties that may not be found in nature. The most fundamental properties of metamaterials are the periodic and sub-wavelength pattern structure. Metamaterials that affect electromagnetic waves in optic wavelengths are called optical metamaterials. The goal of this Thesis was to lay the foundation for design and development of optical metamaterials as potential biomedical sensor. Current biomedical sensors can made of some sensitive biological element (e.g. microorganism and antibodies). The limitations of the biological elements can be due to their susceptibility to extraneous factors such as PH value and temperature. The metamaterials made of gold, aluminum, glass and quartz can bave very high biological stability. Understanding and design of metalmaterials to modulate electromagnetic properties was the focus of the PhD and this was enabled by the use of CST Microwave Studio® software.This PhD made a distinct contribution to the design of two Optical metamaterials. Circular Dichroism (CD) has been widely used to gain information about biomolecules, DNA and organic compounds but, due to problems with accuracy, some indistinct features cannot be detected. The first is Circular Dichroism (CD), which is based on the negative refractive index. The material architectures modeled consisted of a glass substrate and an aluminum nano-ring on top. The research methodology involved adjusting the dimensions of the ring and modelling the impact on CD spectrum. The research in this Thesis shows that controllable CD filter design using optical metamaterial techniques could make it possible to amplify the target signals or unlock jammed signals. The other optical metamaterial designed in this Thesis is a core-shell structure. As a unit cell, the single core-shell and core-shell chain can be built into a biomedical sensor. The aim of this type of sensor is to control the position and value of the Fano dip by regulating the structural parameters of the optical metamaterial. To accomplish this, a concentric spherical structure that consists of a silver core and a quartz (SiO2) shell was designed. The thickness of the shell and the diameter of the core was adjusted independently. The Fano signal was found in the extinction cross section and could be easily identified. This peculiarity allowed the single or multiple optical scales to be marked in the visible spectrum. This can improve efficiency and precision when compared with traditional methods for the detection of biological macromolecules. This work opens new opportunities for fano resonance engineering in plasmonic metamaterials and nanostructures.