Date of Award
2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Physics and Astronomy
Committee Chair
Don A. Gregory
Committee Member
Seyed Sadeghi
Committee Member
Jessica Gaskin
Committee Member
Biswajit Ray
Committee Member
Jeffrey Weimer
Committee Member
James Miller
Research Advisor
Don A. Gregory
Subject(s)
Optical coatings, Light filters, Nanophotonics, Thin films--Optical properties
Abstract
Efficient control of light absorption at the nanoscale has become a popular area of research, leveraging metal, semiconductor, and dielectric thin film technologies to engineer multilayer structures that modulate light through interference. A Fabry-Perot nanocavity can be configured with a dielectric or semiconductor layer sandwiched between two metal layers to exploit interference. This necessarily involves multiple optical paths through a spacer medium. The ensemble structures can be configured for anti-reflection, high-reflection, and dichroism. This dissertation is structured around four main objectives, each aimed at demonstrating the advanced capabilities of these nanocavities in manipulating light. The goals specifically focus on showcasing enhanced narrowband color reflection, dynamically tunable narrowband color absorption, ultra-broadband absorption spanning the visible to near-infrared spectrum, and a comprehensive sensitivity analysis of the dynamically tunable system based on variations in structural parameters. The initial objective was the modeling and experimental realization of a dynamically tunable Fabry-Perot nanocavity, incorporating a metal-oxide-semiconductor (MOS) structure to achieve real-time control of absorption wavelengths in the visible spectrum. This involves using n-type-doped semiconductors like indium antimonide and indium arsenide within an MOS configuration, enabling substantial optical property tuning by electrically controlling the induced carrier accumulation. The second (and easier to experimentally realize) objective entails modeling and building reflective color filters and broadband absorbers for the near-infrared range based on an asymmetric Fabry-Perot nanocavity design. This setup revealed enhanced spectral and angular sensitivity, functioning as an RGB color reflector. The third objective explores the use of an asymmetric Fabry-Perot nanocavity as an ultra-broadband absorber for visible to near-infrared wavelengths, achieving over 80% absorption at incidence angles up to 60 degrees. The final objective quantifies the impact of fabrication inaccuracies on the optical performance of Fabry-Perot nanocavities using Monte Carlo simulations to assess the effect of variations in optical and structural parameters. This research contributes to advancements in the new fields of electrically tunable color filters, solid-state color reflectors, biosensors, photovoltaics, and high-speed electro-optical modulators. The lithography-free fabrication process presented enhances the cost-effectiveness of these devices, which can lead to applications being found in any field employing active or passive optical elements.
Recommended Citation
Dixit, Kirtankumar Pravin, "Design, modeling, and experimental realization of tunable Fabry-Perot nanocavities for broadband and narrow-band applications" (2024). Dissertations. 407.
https://louis.uah.edu/uah-dissertations/407