ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- All Subjects: nanotechnology
Description
A proposed visible spectrum nanoscale imaging method requires material with permittivity values much larger than those available in real world materials to shrink the visible wavelength to attain the desired resolution. It has been proposed that the extraordinarily slow propagation experienced by light guided along plasmon resonant structures is a viable approach to obtaining these short wavelengths. To assess the feasibility of such a system, an effective medium model of a chain of Noble metal plasmonic nanospheres is developed, leading to a straightforward calculation of the waveguiding properties. Evaluation of other models for such structures that have appeared in the literature, including an eigenvalue problem nearest neighbor approximation, a multi- neighbor approximation with retardation, and a method-of-moments method for a finite chain, show conflicting expectations of such a structure. In particular, recent publications suggest the possibility of regions of invalidity for eigenvalue problem solutions that are considered far below the onset of guidance, and for solutions that assume the loss is low enough to justify perturbation approximations. Even the published method-of-moments approach suffers from an unjustified assumption in the original interpretation, leading to overly optimistic estimations of the attenuation of the plasmon guided wave. In this work it is shown that the method of moments approach solution was dominated by the radiation from the source dipole, and not the waveguiding behavior claimed. If this dipolar radiation is removed the remaining fields ought to contain the desired guided wave information. Using a Prony's-method-based algorithm the dispersion properties of the chain of spheres are assessed at two frequencies, and shown to be dramatically different from the optimistic expectations in much of the literature. A reliable alternative to these models is to replace the chain of spheres with an effective medium model, thus mapping the chain problem into the well-known problem of the dielectric rod. The solution of the Green function problem for excitation of the symmetric longitudinal mode (TM01) is performed by numerical integration. Using this method the frequency ranges over which the rod guides and the associated attenuation are clearly seen. The effective medium model readily allows for variation of the sphere size and separation, and can be taken to the limit where instead of a chain of spheres we have a solid Noble metal rod. This latter case turns out to be the optimal for minimizing the attenuation of the guided wave. Future work is proposed to simulate the chain of photonic nanospheres and the nanowire using finite-difference time-domain to verify observed guided behavior in the Green's function method devised in this thesis and to simulate the proposed nanosensing devices.
ContributorsHale, Paul (Author) / Diaz, Rodolfo E (Thesis advisor) / Goodnick, Stephen (Committee member) / Aberle, James T., 1961- (Committee member) / Palais, Joseph (Committee member) / Arizona State University (Publisher)
Created2013
Description
Polarization imaging and polarization microscopy is of great interest in industrial inspection, defense, biomedical and clinical research, food safety, etc. An ideal polarization imaging system suitable for versatile applications should be full-Stokes, compact, broadband, fast, and highly accurate within a large operation angle. However, such a polarization imaging system remains elusive among state-of-the-art technology. Recently, flat optics based on metasurfaces have been explored for polarization detection and imaging. Compared with state-of-art, metasurface-based solutions have the advantages of compactness, great design flexibility, and feasibility for on-chip integration. This dissertation reports a dual wavelength (630 to 670nm and 480nm to 520nm) chiral metasurfaces featured with sub-wavelength dimension, extinction ratio over 10 across a broad operation bandwidth (175nm) and efficiency over 60%, which can be used for detection and generation of circular polarization (Chapter 2).
This dissertation then reports a chip-integrated full-Stokes polarimetric Complementary metal–oxide–semiconductor (CMOS) imaging sensor based on metasurface polarization filter arrays (MPFA) mentioned above. The sensor has high measurement accuracy of polarization states with an angle of view up to 40°. Calibration and characterization of the device are demonstrated, whereby high polarization states measurement accuracy (measurement error <4%) at incidence angle up to ±20° and full Stokes polarization images of polarized objects are shown. (Chapter 3).
A scalable fabrication approach based on nano imprint lithography is demonstrated, with improved fabrication efficiency, lower cost, and higher optical performance up to 10 times compared to EBL process. (Chapter 4).
Several polarization imaging applications including a dual-camera full-Stokes underwater polarization navigation system are discussed. Polarization mapping under clear sky and clear water is demonstrated for proof concept. Enhancing contrast of objects through turbid water and polarization images of silver dendrites are also discussed (Chapter 5).
Though distinctive in its advantages in rich polarization information, most existing Mueller matrix microscope (MMM) operate at single mode, narrow bandwidth with bulky components. This dissertation reports a compact, dual wavelength, dual mode MMM with satisfactory measurement accuracy (Mueller matrix (MM) measurement error≤ 2.1%) using polarimetric imaging sensor mentioned previously, MM imaging of photonic structures, bio-tissues, etc are demonstrated for proof of concept (Chapter 6).
ContributorsZuo, Jiawei (Author) / Yao, Yu (Thesis advisor) / Wang, Chao (Thesis advisor) / Palais, Joseph (Committee member) / Sinha, Kanupriya (Committee member) / Arizona State University (Publisher)
Created2023
Description
Nanophotonics studies the interaction of light with nanoscale devices and nanostructures. This thesis focuses on developing nanoscale devices for optical modulation (saturable absorber and all-optical modulator) and investigating light scattering from nanoparticles for underwater navigation and energy sector application. Saturable absorbers and all-optical modulators are essential to generate ultrashort high-power laser pulses and high-speed communications. Graphene-based devices are broadband, ultrafast, and compatible with different substrates and fibers. Nevertheless, the required fluence to saturate or modulate the optical signal with graphene is still high to realize low-threshold, compact broadband devices, which are essential for many applications. This dissertation emphasizes that the strong light-matter interaction in graphene-plasmonic hybrid metasurface greatly enhances monolayer graphene’s saturable absorption and optical signal modulation effect while maintaining graphene’s ultrafast carrier dynamics. Furthermore, based on this concept, simulation models and experimental demonstrations are presented in this dissertation to demonstrate both subwavelength (~λ/5 in near-infrared and ~λ/10 in mid-infrared) thick graphene-based saturable absorber (with record-low saturation fluence (~0.1μJ/cm2), and ultrashort recovery time (~60fs) at near-infrared wavelengths) and all-optical modulators ( with 40% reflection modulation at 6.5μm with ~55μJ/cm2 pump fluence and ultrafast relaxation time of ~1ps at 1.56μm with less than 8μJ/cm2 pump fluence).
Underwater navigation is essential for various underwater vehicles. However, there is no reliable method for underwater navigation. This dissertation presents a numerical simulation model and algorithm for navigation based on underwater polarization mapping data. With the methods developed, for clear water in the swimming pool, it is possible to achieve a sun position error of 0.35˚ azimuth and 0.03˚ zenith angle, and the corresponding location prediction error is ~23Km. For turbid lake water, a location determination error of ~100Km is achieved. Furthermore, maintenance of heliostat mirrors and receiver tubes is essential for properly operating concentrated solar power (CSP) plants. This dissertation demonstrates a fast and field deployable inspection method to measure the heliostat mirror soiling levels and receiver tube defect detection based on polarization images. Under sunny and clear sky conditions, accurate reflection efficiency (error ~1%) measurement for mirrors with different soiling levels is achieved, and detection of receiver tube defects is demonstrated.
ContributorsRafique, Md Zubair Ebne (Author) / Yao, Yu (Thesis advisor) / Palais, Joseph (Committee member) / Zhang, Yong-Hang (Committee member) / Sukharev, Maxim (Committee member) / Arizona State University (Publisher)
Created2022