Date of Award

9-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Engineering Physics

First Advisor

Michael A. Marciniak, PhD

Abstract

Modern optical materials are engineered to be used as optical devices in specific applications, such as optical computing. For optical computing, efficient forms of a particular device, the optical switch, still have not been successfully demonstrated. This problem is addressed in this research through the use of designed optical metamaterials, specifically, hyperbolic metamaterials, which offer the possibility of large non-linear properties with a low switching intensity. One-dimensional layered hyperbolic metamaterials composed of alternating layers of metal and dielectric were used here, with ITO as the metal and SiO2 as the dielectric. The non-linear behavior of the ITO/SiO2 layered structure was first modeled and optimized. Then, samples were fabricated based on this optimized design through physical vapor deposition at the Materials and Manufacturing Directorate of the Air Force Research Laboratory. Linear and non-linear properties of these samples were measured by ellipsometry and the Z-scan technique, respectively. These materials showed a large enhancement of their effective nonlinear properties, and an intensity-dependent switching behavior where the sign of the non-linear absorption coefficient changes from positive to negative. This switching behavior has a switching intensity near 15 GW/cm2 and switching width of about 0.15. This is the first experimental demonstration of such behavior in a simple one-dimensional layered hyperbolic metamaterial. Since this behavior is tunable, this technique may now be used to further engineer devices for specific applications. The unique properties of these materials increase their potential for use in optical switching applications.

AFIT Designator

AFIT-ENP-DS-22-S-042

DTIC Accession Number

AD1181201

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