Wangshi Zhao


The development of metamaterials has opened the door for engineering electromagnetic properties by subwavelength artificial "atoms", and hence accessing new properties and functionalities which cannot be found among naturally occurring materials. In particular, metamaterials enable the flexibility of independently controlling the permittivity and permeability to be almost any arbitrary value, which promises to achieve deep subwavelength confinement and focusing of electromagnetic waves in different spectrum regimes. The next stage of this technological revolution will be focused on the development of active and controllable metamaterials, where the properties of the metamaterials are expected to be tuned by external stimuli. In this sense, some natural materials are also promising to provide the tunable capability, particularly in the near infrared and terahertz domains either by applying a voltage or shining light on the materials. The objective of this dissertation is to investigate novel metamaterials and explore three important applications of them: subwavelength waveguiding, imaging and modulation. The first part of this dissertation covers the theory, design and fabrication of several different types of metamaterials, which includes artificially designed metamaterials and some naturally existing materials. The second part demonstrates metal gratings functioning as designer surface plasmonic waveguides support deep subwavelength surface propagation modes at microwave frequency. The third part proposes multilayered metal-insulator stack as indefinite metamaterial that converts evanescent waves to propagating waves, hence deep subwavelength image can be observed. The fourth part explores the tunability of several natural materials - gallium (Ga), indium tin oxide (ITO) and graphene, and demonstrates electro-optical (EO) modulators based on these materials can be achieved on nano-scale. The final part summarizes the work presented in this dissertation and also discusses some future work for photodetection, photovoltaics, and modulation.

Library of Congress Subject Headings

Metamaterials; Semiconductors--Materials; Modulators (Electronics)--Materials; Wave guides--Materials; Negative refractive index

Publication Date


Document Type


Student Type


Degree Name

Microsystems Engineering (Ph.D.)

Department, Program, or Center

Microsystems Engineering (KGCOE)


Zhaolin Lu


Physical copy available from RIT's Wallace Library at TK7871.15.M48 Z46 2014


RIT – Main Campus

Plan Codes