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MICRO-OPTIC-SPECTRAL-SPATIAL-ELEMENTS (MOSSE)
Title
MICRO-OPTIC-SPECTRAL-SPATIAL-ELEMENTS (MOSSE).
Creator
Mehta, Alok, Johnson, Eric, University of Central Florida
Abstract / Description
Over a wide range of applications, optical systems have utilized conventional optics in order to provide the ability to engineer the properties of incident infra-red fields in terms of the transmitted field spectral, spatial, amplitude, phase, and polarization characteristics. These micro/nano-optical elements that provide specific optical functionality can be categorized into subcategories of refractive, diffractive, multi-layer thin film dichroics, 3-D photonic crystals, and polarization...
Show moreOver a wide range of applications, optical systems have utilized conventional optics in order to provide the ability to engineer the properties of incident infra-red fields in terms of the transmitted field spectral, spatial, amplitude, phase, and polarization characteristics. These micro/nano-optical elements that provide specific optical functionality can be categorized into subcategories of refractive, diffractive, multi-layer thin film dichroics, 3-D photonic crystals, and polarization gratings. The feasibility of fabrication, functionality, and level of integration which these elements can be used in an optical system differentiate which elements are more compatible with certain systems than others. With enabling technologies emerging allowing for a wider range of options when it comes to lithographic nano/micro-patterning, dielectric growth, and transfer etching capabilities, optical elements that combine functionalities of conventional optical elements can be realized. Within this one class of optical elements, it is possible to design and fabricate components capable of tailoring the spectral, spatial, amplitude, phase, and polarization characteristics of desired fields at different locations within an optical system. Optical transmission filters, polarization converting elements, and spectrally selective reflecting components have been investigated over the course of this dissertation and have been coined  MOSSE,' which is an acronym for micro-optic-spectral-spatial-elements. Each component is developed and fabricated on a wafer scale where the thin film deposition, lithographic exposure, and transfer etching stages are decoupled from each other and performed in a sequential format. This facilitates the ability to spatially vary the optical characteristics of the different MOSSE structures across the surface of the wafer itself.
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Date Issued
2007
Identifier
CFE0001962, ucf:47457
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001962
Nanoscale Control of Gap-plasmon Enhanced Optical Processes
Title
Nanoscale Control of Gap-plasmon Enhanced Optical Processes.
Creator
Lumdee, Chatdanai, Kik, Pieter, Dogariu, Aristide, Kuebler, Stephen, Huo, Qun, University of Central Florida
Abstract / Description
Surface plasmon resonances of metal nanostructures have been studied intensely in recent years. The strong plasmon-mediated electric field enhancement and field confinement well beyond the diffraction limit has been demonstrated to improve the performance of optical devices including ultrasensitive sensors, light emitters, and optical absorbers. A plasmon resonance mode of particular recent interest is the gap plasmon resonance that occurs on closely spaced metallic structures. In contrast to...
Show moreSurface plasmon resonances of metal nanostructures have been studied intensely in recent years. The strong plasmon-mediated electric field enhancement and field confinement well beyond the diffraction limit has been demonstrated to improve the performance of optical devices including ultrasensitive sensors, light emitters, and optical absorbers. A plasmon resonance mode of particular recent interest is the gap plasmon resonance that occurs on closely spaced metallic structures. In contrast to plasmon resonances supported by isolated metal nanostructures, coupled nanostructures provide additional spectral and spatial control over the plasmon resonance response. For example, the resonance frequencies of metal nanoparticle dimers depend strongly on the gap size between the nanoparticles. Gap plasmons can produce local electric field enhancement factors that are several orders of magnitude stronger and more confined than surface plasmon resonances of isolated plasmonic nanospheres. The reliance of gap plasmons on few-nanometer separation between nanostructures makes it difficult to prepare gap-plasmon supporting structures with predictable resonance frequency and field enhancement. A structure that avoids this challenge is the film-coupled nanoparticle (NP). Similar to nanoparticle dimers, a nanoparticle on a supporting metallic film (or NP-on-a-mirror) can offer a strong coupling between the particle and its local environment, in this case the supporting film instead of adjacent nanoparticles, enabling strongly confined gap-plasmon modes. The NP-on-a-mirror geometry has been shown to produce reproducible gap plasmon resonances in a chemically and thermally robust, easy to fabricate structure. In this Thesis, we first present a scheme for controlling the gap plasmon resonance frequency of single gold nanoparticles using aluminum oxide coated metal films. We demonstrate experimentally and numerically that the gap-plasmon resonance of single gold nanoparticles can be tuned throughout the visible range by controlling the aluminum oxide thickness via anodization. In a separate study of Au NP on Al2O3 coated gold films it is shown that the oxide coating improves the stability of the structure under intense laser irradiation. An combined experimental and numerical analysis of the spectral response of Au NP on rough Au films shows that a film roughness of a few nanometer can affect the gap plasmon resonance in the absence of an oxide spacer layer. A photoluminescence study of single gold nanoparticles on an Al2O3 coated gold film shows that the gap-plasmon resonance of this type of plasmonic structure can increase gold photoluminescence by more than four orders of magnitude. Related numerical simulations reveal that the local photoluminescence enhancement of a gold nanoparticle on an Al2O3 coated gold film can be as high as one million near the particle-film junction. Finally, a new plasmonic sensing element was proposed based on our findings in the previous chapters. This proposed hole-in-one structure offers several attractive features including an easily optically accessible gap plasmon mode, while maintaining a relatively simple fabrication method. Taken together, the research presented in this Thesis demonstrates how the resonance frequency, field enhancement, mode polarization, structural stability, and structure reliability can be controlled at the nanoscale. The knowledge gained in the course of this work could lead to further development of nanophotonic devices that utilize extremely confined optical fields and precisely controlled resonance frequencies.
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Date Issued
2015
Identifier
CFE0005972, ucf:50772
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005972