Designing Enhanced Nonlinearity in Plasmonic Devices with Epsilon-Near-Zero Films

<p>The growing demand for energy-efficient optical information processing motivates compact nonlinear photonic devices that can operate at low power. Silicon photonics is a mature platform for linear optical functions, but nonlinear operation remains challenging because of its weak Kerr response, two-photon absorption at telecommunication wavelengths, and limited compatibility with deeply subwavelength plasmonic confinement. This thesis computationally investigates epsilon-near-zero thin films integrated into plasmonic waveguide architectures as a route toward stronger light–matter interaction in compact nonlinear devices.</p> <p>Two waveguide geometries are examined: a hybrid metal-insulator-metal plasmonic slab waveguide incorporating an ultrathin indium tin oxide epsilon-near-zero layer (5–50 nm), and a dielectric-loaded surface plasmon polariton waveguide. Finite element method simulations were performed in COMSOL Multiphysics 6.2 using the Wave Optics Module. Parametric sweeps over epsilon-near-zero layer thickness, metal cladding material, and operating wavelength were used to evaluate effective nonlinear response, propagation loss, and normalized loss-adjusted figures of merit.</p> <p>For the metal-insulator-metal geometry, thinner epsilon-near-zero layers produced larger effective nonlinear coefficients, with the 5 nm silver–indium tin oxide case reaching 2.66 rad/(W·m) at 1561.1 nm. This enhancement also increased propagation loss, so the useful design space is governed by a trade-off between confinement and attenuation. In the dielectric-loaded surface plasmon polariton geometry, the nonlinear overlap metric peaked near 50 nm indium tin oxide thickness, while the normalized loss-adjusted figure of merit favored thinner layers because loss increased with indium tin oxide thickness.</p> <p>The simulations identify silver–indium tin oxide metal-insulator-metal structures as strong candidates for high-confinement nonlinear response and dielectric-loaded surface plasmon polariton structures as a more fabrication-accessible alternative with different loss and overlap trade-offs. The main limitation of the present model is that the nonlinear coefficient of indium tin oxide was treated as wavelength independent, so the expected resonant enhancement near the epsilon-near-zero crossing was not fully captured. These results provide a computational baseline for future epsilon-near-zero-integrated nonlinear photonic devices and for follow-up simulations using wavelength-dependent nonlinear material parameters.</p>

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Electrical Engineering and Computer Science

Year

2026

Author dc:creator

• Le, Kevin Tran

Contributors dc:contributor

• Mark C. Harrison, Ph.D.
• Mohamed Allali, Ph.D.
• Maryam Etezadbrojerdi, Ph.D.

• nonlinear optics
• epsilon-near-zero (ENZ)
• plasmonics
• nanophotonics
• thin films
• metamaterials
• Atomic, Molecular and Optical Physics
• Computer Sciences
• Condensed Matter Physics
• Electrical and Computer Engineering
• Electromagnetics and Photonics
• Electronic Devices and Semiconductor Manufacturing
• Engineering
• Engineering Physics
• Materials Science and Engineering
• Nanoscience and Nanotechnology
• Nanotechnology Fabrication
• Other Computer Sciences
• Physical Sciences and Mathematics
• Physics
• Semiconductor and Optical Materials

Repository record dc:identifier

https://digitalcommons.chapman.edu/eecs_theses/12

OAI identifier oai:identifier

oai:digitalcommons.chapman.edu:eecs_theses-1012