Investigation of Distinct Magnetic Field in Metamaterials through Effective Medium Theorem
Date Issued
2012
Date
2012
Author(s)
Chen, Yi-Huan
Abstract
Subwavelength structure, a structure unit which is smaller than wavelength and thus induces some specific properties that can’t be explained by classic electromagnetic theorem, plays a crucial role in the field of photoelectronics nowadays. It can be found easily in nature, and since the wavelength of visible light ranges form 400 to 700 nm, it is also called a nano-structure. Through the nano-level process approaches, an artificial material beyond the micron-level can display distinct features from what they can be seen under a microscope; the features are called metamaterials. Metamaterials is widely used in antenna, stealth, sensor, etc. This thesis focuses on analyze and design the stratified metal dielectric metamaterials (SMDMs) which can lead to enhancement of the magnetic field incident inthe structure.
Normally, metamaterials are made of subwavelength structures arranged periodically due to the fact that such arrangements produce extra momentum which cause surface plasma resonance (SPR) and hence enhance the extraordinary phenomenon of electromagnetic wave. However, even an unit cell of the sandwich structure composited of metal and dielectric can reach the unusual magnetic response such as diamagnetism or high quality paramagnetism explicitly without the structure consisting of non-magnetic materials. Therefore, by modifying only two factors—the permittivity and thickness of every slab—the optical properties of the structure can be controlled simply.
The effective medium theorem (EMT) is often used to analyze the metamaterial structure, in which the structure can be regarded as an isotropic or anisotropic effective medium and be described by retrieving the effective optical parameters. When resonance occurs, the effect optical parameters also vary abruptly. However, the numerical error may occur upon the retrieval process, and is amplified at some specific singular points. Therefore, the EMT has to be based on physical phenomenon and be modified appropriately. The detail will be discussed in the second and the third chapter.
Subjects
Subwavelength structure
SMDM
Sandwich strcture
Diamagnetism
EMT
Optical parameter retrieval
Fabry-Perot resonance
Type
thesis
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