APPLICATION SPECIFIC METAMATERIAL STRUCTURES, DEVICES AND COMPONENTS

Abstract

This thesis presents a detailed account of the research work conducted by the author in the area of metamaterials which includes certain novel application-speci c designs, as well as, a few unanticipated applications of the existing designs of metamaterials. In this work a broad spectrum of metamaterials ranging from positive to negative through zero refractive index have been explored and employed for useful applications. An all-dielectric metasurface has been used to make high quality laser cavity by reducing the losses due to nite re ectivity. Besides high quality factor, the metasurface cavity has a compact design which improves its practicality. The metamaterial used here is a purely dielectric perfect re ector having near zero impedance. Secondly, a novel design of a lossy dielectric based metamaterial perfect absorber has been proposed whose working principle is substantially di erent from existing and commonly used metallic patch type metamaterials absorbers. Both these metamaterials lie in positive refractive index domain. In the negative index domain, a novel design of split-nanotube based negative index metamaterial has been proposed which is an extruded version of a conventional split ring resonator. The split-nanotube has an upper hand over a split ring resonator in terms of both { strength of magnetic resonance and ease of fabrication on a substrate. Between positive and negative index, lies the zero index region. The recent development of zero refractive index metamaterials (ZIMs) have unfolded multiple unprecedented properties leading to astonishing applications like wavefront engineering, electromagnetic cloaking, zero phase transfer, etc. This thesis includes two major works on zero index metamaterials, rst is a zero index metamaterial based unidirectional nanoantenna which makes use of the well acknowledged dielectric rods-in-air type ZIM. The second one is a novel design of zero index metamaterial suitable for both TE and TM polarization which is an improvement over the existing ZIM designs which are suitable for only one type of polarization. Metamaterials hold tremendous possibilities for broad range of applications from medicine to optical computing, communication, energy harvesting, defense, imaging, etc. In this research work almost all the types and domains of metamaterials have been ventured, explored & analyzed, and attempts have been made to suggest novel designs and applications.