Nanophotonic Structures: Fundamentals and Applications in Narrowband Transmission Color Filtering

Author: Fleischman, Dagny

Year: 2019

Degree: Dissertation (Ph.D.)

Advisor: Atwater, Harry Albert

Committee Members: Greer, Julia R.; Scherer, Axel; Schwab, Keith C.; Atwater, Harry Albert

Option: Materials Science

DOI: 10.7907/RA1G-GS84

Abstract

The optical properties of materials can be manipulated by structures roughly the size of the wavelength of light of interest. For visible wavelengths, many different types of structures sized on the order of 10s-100s of nanometers have been used to engineer materials to produce a targeted optical response. Multilayer stacks of nanoscale metal and dielectric films are a widely explored geometry that has been used to make composite materials with effective optical properties that vary significantly from their constituent films. In this thesis, carefully designed multilayer stacks were used to induce artificial magnetism in non-magnetic materials, opening new directions for tailoring wave propagation in optical media. By perforating these multilayer structures with an array of sub-wavelength slits, these nanophotonic structures were shown to be able to function as narrowband transmission color filters. Using numerical optimization methods, these narrowband filterswere further refined and simplified to only require a single thin film sandwiched between two mirrors to achieve this high resolution spectral filtering. Novel methods were used to fabricate these ultracompact narrowband transmission color filters, which were shown to possess extremely narrow transmission resonances that can be controllably pushed across the visible and near IR parts of the spectrum. These mirrored color filters have footprints as small as 400 nm, well below the size of state-of-the-art CMOS pixels, inviting the possibility for integrating multi- and hyperspectral imaging capabilities into small portable electronic devices.

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