Thesis advisor: Willie J. Padilla / Progress in the field of metamaterials has started coming to a point where the field may finally begin to emerge as a viable solution to many electromagnetic challenges facing the community. No where is that more true then at terahertz frequencies where there lies an immense opportunity for growth. The development of mature technologies within this region of the electromagnetic spectrum would provide a valuable resource to become available for a multitude of applications. In order to achieve this, the necessary first steps of identifying viable materials and paths to integrate these with metamaterials will need to be completed. In this dissertation, we examine several different paths to achieve dynamic metamaterial electromagnetic response at terahertz frequencies, and demonstrate several paths to package these devices into imaging systems. In Chapter 1, we introduce the basic theory and design principles of metamaterials. We also describe the experimental techniques involved in the study of terahertz metamaterials. Chapter 2 presents a computational and experimental study investigating the integration of high electron mobility transistors with metamaterials allowing for high speed modulation of incident terahertz radiation. In Chapters 3 and 4, we investigate several different paths to create tunable terahertz metamaterial absorbers. Chapter 3 presents an investigation where we encapsulate a metametarial absorber unit cell with liquid crystals. We study both computationally and experimentally the tuning mechanism of the absorber as the liquid crystal refractive index is controlled as a function of the applied electric field strength and modulation frequency. In Chapter 4, we form a doped semiconducting metamaterial spatial light modulator with multi-color super-pixels composed of arrays of electronically controlled terahertz metamaterial absorbers. We computationally and experimentally study the independent tunability of each pixel in the spatial array and demonstrate high speed modulation. Chapter 5 introduces a multiplex imaging approach by using a terahertz spatial light modulator to enable terahertz imaging with a single pixel detector. We demonstrate the capability for high speed image acquisition, currently only limited by the commerical software used to reconfigure the spatial masks. We also configure the system to capture high fidelity images of varying complexity. In Chapter 6, we show how a metamaterial absorber can be implemented into a detector focal plane array for high sensitivity, low mutual coupling, and broad angle performance. Finally, we summarize in Chapter 7 the achievments of the research presented and highlight the direction of future work. / Thesis (PhD) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

The angular momentum of light originates from two sources: one is the spin angular momentum (SAM) of individual photons, which is related to the polarization of light and the other is the orbital angular momentum (OAM) associated with helical wavefront of the light if it is helically phased (complex phase front). A beam of light that is composed of photons possessing both OAM and SAM states can be used in different areas of study such as rotating microscopic particles, interacting with nonlinear materials, investigating atom-light interactions, communication and medical imaging technologies, quantum information, quantum entanglement and etc. In this dissertation we study coherent beams that convey photons in superposition states of polarization and complex phase front. Our study includes two fields: (I) classical wave-like behavior with visible light in the field of singular optics. (II) quantum particle-like behavior of photons of light in the field of quantum-entangled optics. The approach is to investigate the state of such photons both mathematically and experimentally in classical-singular and quantum-entangled fields. We discuss seven projects based on this research. In one project we present a new method to encode OAM modes into perpendicular polarization components and making superpositions of polarization and spatial modes mapped by Poincare sphere. In another project using spatial light modulators (SLM) we realized highorder disclination patterns in the polarization map of the cross section of the beam. We also realize new forms of polarization disclination patterns (line patterns where rotational invariance is violated) known as monstars that were not previously seen. We proposed a new definition for characterizing these patterns since they can have zero or negative singularity index. In another project, instead of SLM we used q-plates to generate new forms of monstars. We proposed a robust and easy method for determining the topological charge of a complex phase front beam by inspecting the interference pattern the beam reflected from a wedged optical flat. In another project we encoded OAM modes onto orthogonal polarization components of a photon from an entangled pair and investigated the quantum entanglement. We also prepared a polarization entangled state and calculated some measures of entanglement. We summarize the projects and discuss the future prospects. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

The amount of wireless data traffic has been increasing exponentially. This results in the shortage of radio frequency (RF) spectrum. In order to alleviate the looming spectrum crisis, visible light communication (VLC) has emerged as a supplement to RF techniques. VLC uses light emitting diodes (LEDs) for transmission and employs photodiodes (PDs) for detection. With the advancement of the LED technology, LEDs can now fulfil two functions at the same time: illumination and high-speed wireless communication. In a typical indoor scenario, each single light fixture can act as an access point (AP), and multiple light fixtures in a room can form a cellular wireless network. We refer to this type of networks as ‘optical attocell network’. This thesis focuses on interference mitigation in optical attocell networks. Firstly, the downlink inter-cell interference (ICI) model in optical attocell networks is investigated. The conventional ray-tracing channel model for non-line-of-sight (NLOS) path is studied. Although this model is accurate, it leads to time-consuming computer simulations. In order to reduce the computational complexity, a simplified channel model is proposed to accurately characterise NLOS ICI in optical attocell networks. Using the simplified model, the received signal-to-interference-plus-noise ratio (SINR) distribution in optical attocell networks can be derived in closed-form. This signifies that no Monte Carlo simulation is required to evaluate the user performance in optical attocell networks. Then, with the knowledge of simplified channel model, interference mitigation techniques using angle diversity receivers (ADRs) are investigated in optical attocell networks. An ADR typically consists of multiple PDs with different orientations. By using proper signal combining schemes, ICI in optical attocell networks can be significantly mitigated. Also, a novel double-source cell configuration is proposed. This configuration can further mitigate ICI in optical attocell networks in conjunction with ADRs. Moreover, an analytical framework is proposed to evaluate the user performance in optical attocell networks with ADRs. Finally, optical space division multiple access (SDMA) using angle diversity transmitters is proposed and investigated in optical attocell networks. Optical SDMA can exploit the available bandwidth resource in spatial dimension and mitigate ICI in optical attocell networks. Compared with optical time division multiple access (TDMA), optical SDMA can significantly improve the throughput of optical attocell networks. This improvement scales with the number of LED elements on each angle diversity transmitter. In addition, the upper bound and the lower bound of optical SDMA performance are derived analytically. These bounds can precisely evaluate the performance of optical SDMA systems. Furthermore, optical SDMA is shown to be robust against user position errors, and this makes optical SDMA suitable for practical implementations.

Energy generating processes like the citric acid cycle are a pivotal part of metabolism. Members of the 2-oxoacid dehydrogenase multienzyme complex (OADHC) superfamily feed into and act within the citric acid cycle. OADHCs are composed of three enzymes: 2-oxoacid decarboxylase (E1), dihydrolipoamide acyltransferase (E2) and dihydrolipoamide dehydrogenase (E3). Covalent attachment of lipoic acid (LA) to E2 is essential for overall OADHC activity. Although thought to be absent in Archaea, it has recently been found that Thermoplasma acidophilum has all the components for an active recombinant OADHC (Heath et al., 2007). Recent studies have further suggested that Tp. acidophilum may have an enzyme to covalently attach LA to E2 (Sun et al., 2007; McManus et al., 2006). This work describes the cloning and recombinant expression of the Thermoplasma lipoate protein ligase (Tp. LplA), its C-terminal domain and a fusion protein composed of the above two proteins. Both proteins are required for lipoylation of E2 in vitro. For the first time, in vivo lipoylation of E2 in Tp. acidophilum cell cultures is also being reported. The effect of lipoylation and temperature on the Thermoplasma OADHC assembly has also been studied. This study revealed the temperature dependence of the E2 core and the whole complex assembly. These findings are in line with the optimum growth temperature of Tp. acidophilum. Dynamic light scattering and analytical ultracentrifugation were used to determine the molecular mass of whole OADHC. The molecular mass was determined to be 5 MDa with an octahedral geometry of the E2 core. The results of this work strengthen the assumption that these enzyme systems may have had or potentially have a role in the Archaea. This may hold further clues to the evolutionary relationship between the three kingdoms of life and the role of OADHCs/lipoylation in the Archaea. The temperature dependent assembly of the complex and thermostability of these proteins may also provide a model to study thermostability and protein-protein interactions at high temperatures.

by Pang Kam Moon. / Title also in Chinese characters. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 120-121). / LIST OF FIGURES --- p.iv / ACKNOWLEDGEMENTS --- p.x / ABSTRACT --- p.xi / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter CHAPTER 2 --- SPONTANEOUS BRILLOUIN SCATTERING IN MICRODROPLETS --- p.10 / Chapter 2.1 --- Outline of the theory of Spontaneous Brillouin Scattering / Chapter 2.2 --- Low-Q Spontaneous Brillouin Scattering / Chapter 2.3 --- High-Q Spontaneous Brillouin Scattering / Chapter CHAPTER 3 --- FORMULATION AND RESULTS OF STEADY STATE SBS --- p.16 / Chapter 3.1 --- SBS in Extended and Spherical Media / Chapter 3.2 --- Formulation / Chapter 3.3 --- Monochromatic Plane Wave with Definite Helicity / Chapter 3.4 --- Lorentzian Approximation to J(z) / Chapter 3.5 --- Edge Illumination / Chapter CHAPTER 4 --- TRANSIENT EFFECTS ON INTERNAL INTENSITY --- p.56 / Chapter 4.1 --- Enhancements for Internal Intensity / Chapter 4.2 --- Formulation for Transient Incident Pulse Gaussian Profile / Chapter 4.3 --- Absorption Effects / Chapter CHAPTER 5 --- TRANSIENT STIMULATED BRILLOUIN SCATTERING --- p.74 / Chapter 5.1 --- Slowly Varying Phase and Amplitude Approximation / Chapter 5.2 --- Long Temporal Gaussian Profile Incident Light / Chapter 5.3 --- Short Temporal Gaussian Profile Incident Light / Chapter CHAPTER 6 --- SBS IN MICRODROPLETS WITH ABSORPTION --- p.82 / Chapter 6.1 --- Steady State SBS with Absorption / Chapter 6.2 --- Long Temporal Gaussian Profile Incident Light / Chapter 6.3 --- Short Temporal Gaussian Profile Incident Light / Chapter 6.4 --- Singly Resonant SBS / Chapter CHAPTER 7 --- CONCLUSION --- p.98 / APPENDIX A --- p.100 / APPENDIX B --- p.102 / APPENDIX C --- p.106 / APPENDIX D --- p.108 / REFERENCES --- p.120

by Ng Chiu-king. / Title also in Chinese characters. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 189-195). / ACKNOWLEDGEMENTS --- p.v / ABSTRACT --- p.vi / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter CHAPTER 2 --- STANDARD MIE SCATTERING AND MORPHOLOGY DEPENDENT RESONANCES --- p.5 / Chapter 2.1 --- General Descriptions --- p.6 / Chapter 2.1.1 --- Nonresonant Scattering --- p.13 / Chapter 2.1.1.1 --- Internal Intensity --- p.13 / Chapter 2.1.1.2 --- Understanding in Terms of Geometric Optics --- p.14 / Chapter 2.1.2 --- Resonances --- p.19 / Chapter 2.1.2.1 --- Q-factor --- p.23 / Chapter 2.1.2.2 --- Internal Intensity --- p.25 / Chapter 2.1.2.3 --- Understanding in Terms of Geometric Optics --- p.28 / Chapter 2.2 --- Theories --- p.31 / Chapter 2.2.1 --- Nonresonances --- p.31 / Chapter 2.2.2 --- Resonances --- p.32 / Chapter 2.2.2.1 --- TE Mode in Lorentzian Form --- p.32 / Chapter 2.2.2.2 --- Degradation due to Absorption --- p.35 / Chapter 2.2.3 --- Response to a Pulse --- p.37 / Chapter 2.2.3.1 --- Nonresonant Modes --- p.38 / Chapter 2.2.3.2 --- Resonant Modes --- p.39 / Chapter CHAPTER 3 --- NONLINEAR MIE SCATTERING AND THE PROPOSED MECHANISMS --- p.42 / Chapter 3.1 --- NRL Experiment --- p.42 / Chapter 3.1.1 --- Observations --- p.42 / Chapter 3.1.2 --- Parameters --- p.43 / Chapter 3.1.3 --- Evidence of Q Degradation --- p.45 / Chapter 3.2 --- Proposed Mechanisms --- p.49 / Chapter 3.2.1 --- Volume Perturbation due to electrostrictively Generated Acoustic Waves --- p.50 / Chapter 3.2.2 --- Surface Perturbation due to Shape Distortion --- p.50 / Chapter 3.2.3 --- Stimulated Brillouin Scattering --- p.51 / Chapter 3.2.4 --- Bubbles Formation --- p.52 / Chapter 3.3 --- Envelope Fluctuation --- p.53 / Chapter CHAPTER 4 --- ELECTROSTRICTION AND THE PERTURBATION THEORY OF THE LINEWIDTH --- p.55 / Chapter 4.1 --- Electrostriction --- p.55 / Chapter 4.2 --- Perturbation of the Linewidth --- p.42 / Chapter 4.2.1 --- Theory --- p.58 / Chapter 4.2.2 --- Remarks --- p.60 / Chapter CHAPTER 5 --- ELECTROSTRICTIVELY GENERATED ACOUSTIC VIBRATIONS --- p.64 / Chapter 5.1 --- Estimate of Density Change --- p.64 / Chapter 5.2 --- Pressure Disturbances --- p.65 / Chapter 5.3 --- Electrostrictively Coupled Coefficients --- p.67 / Chapter 5.4 --- Validity of Impulse Approach --- p.70 / Chapter 5.5 --- An Expedient Model --- p.71 / Chapter 5.5.1 --- Fractional Change in Density --- p.73 / Chapter 5.5.2 --- Q Degradation --- p.81 / Chapter 5.6 --- Exact Result --- p.88 / Chapter 5.7 --- Nonimpulse Approach to Resonant Mode --- p.89 / Chapter 5.7.1 --- Results --- p.91 / Chapter 5.8 --- Chapter Conclusion --- p.93 / Chapter CHAPTER 6 --- LOW-FREQUENCY SURFACE OSCILLATIONS --- p.94 / Chapter 6.1 --- Surface Bulging --- p.95 / Chapter 6.1.1 --- Equation of Motion --- p.97 / Chapter 6.1.2 --- Results --- p.100 / Chapter 6.1.3 --- Justification of Incompressibi1ity --- p.109 / Chapter 6.2 --- Q Degradation --- p.110 / Chapter 6.2.1 --- Experimental Situation --- p.111 / Chapter 6.2.1.1 --- Single Pulse --- p.114 / Chapter 6.2.1.2 --- Pulse Train --- p.116 / Chapter 6.2.2 --- Hypothetical Bulging --- p.119 / Chapter 6.3 --- Further Investigations --- p.123 / Chapter 6.4 --- Chapter Conclusion --- p.130 / Chapter CHAPTER 7 --- STIMULATED BRILLOUIN SCATTERING --- p.131 / Chapter 7.1 --- General Descriptions --- p.132 / Chapter 7.1.1 --- Resonant SBS --- p.133 / Chapter 7.1.2 --- One Gain Mode --- p.136 / Chapter 7.2 --- SBS Pressure Disturbances --- p.137 / Chapter 7.3 --- Pulse Train --- p.140 / Chapter 7.3.1 --- Necessity of Projection --- p.141 / Chapter 7.3.2 --- Amplitude of Projected Mode --- p.143 / Chapter 7.4 --- Results --- p.145 / Chapter 7.5 --- Remarks --- p.150 / Chapter 7.6 --- Chapter Conclusion --- p.155 / Chapter CHAPTER 8 --- BUBBLE FORMATION --- p.156 / Chapter 8.1 --- Degradation due to Cavitations --- p.157 / Chapter 8.2 --- Coalescence of Gas Bubbles --- p.159 / Chapter 8.3 --- Acoustic Cavitation --- p.161 / Chapter 8.4 --- Chapter Conclusion --- p.165 / Chapter CHAPTER 9 --- CONCLUSION AND DISCUSSION --- p.166 / APPENDIX A --- p.170 / APPENDIX B --- p.175 / APPENDIX C --- p.180 / APPENDIX D --- p.184 / APPENDIX E --- p.187 / REFERENCES --- p.189

by Sin Lai Yi, Mandy. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 120-121). / Text in English; abstracts in English and Chinese. / by Sin Lai Yi, Mandy. / Abstract --- p.ii / 論文摘要 --- p.iii / Acknowledgements --- p.iv / Table of Contents --- p.v / List of Figures --- p.ix / List of Tables --- p.xiii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Adhesion --- p.1 / Chapter 1.2 --- Adhesion issues in PLEDs --- p.1 / Chapter 1.3 --- Literature review of the adhesion measurement techniques --- p.4 / Chapter 1.3.1 --- Methods involving detachment normal to the interface --- p.4 / Chapter 1.3.1.1 --- Direct pull-off method --- p.5 / Chapter 1.3.2 --- Methods based upon the application of lateral stresses for detachment --- p.7 / Chapter 1.3.2.1 --- Scotch tape method --- p.7 / Chapter 1.3.2.2 --- Peel test --- p.8 / Chapter 1.4 --- Motivations and aims of studies --- p.11 / Chapter 1.5 --- Outline of the thesis --- p.12 / Chapter Chapter 2 --- Experimental and Instrumentation / Chapter 2.1 --- Sample preparation --- p.13 / Chapter 2.2 --- Instrumentation --- p.13 / Chapter 2.1.1 --- Modified Scotch tape method --- p.13 / Chapter 2.2.2 --- Atomic force microscope --- p.23 / Chapter 2.2.3 --- X-ray photoelectron spectroscopy --- p.26 / Chapter 2.2.4 --- Radio-frequency (RF) plasma etching system --- p.27 / Chapter Chapter 3 --- Verification of the modified Scotch tape method / Chapter 3.1 --- Introduction --- p.31 / Chapter 3.2 --- Verification Test One ´ؤ Measurement against different adhesive tapes --- p.31 / Chapter 3.3 --- Verification Test Two ´ؤ Measurement with different crosshead speeds --- p.40 / Chapter 3.4 --- Verification Test Three ´ؤ Measurement of adhesive tapes with different sizes --- p.46 / Chapter 3.5 --- Summary --- p.51 / Chapter Chapter 4 --- Adhesion of gold films coated on the plasma treated ITO / Chapter 4.1 --- Introduction --- p.53 / Chapter 4.2 --- Characteristics of RF plasma etching --- p.53 / Chapter 4.2.1 --- Test One ´ؤ Study the relationship between sputtering time and sputtering depth --- p.54 / Chapter 4.2.2 --- Test Two - Study the relationship beteen self-bias voltage and sputtering depth --- p.54 / Chapter 4.3 --- Modification of the surface morphology of the Ar plasma treated ITO --- p.57 / Chapter 4.4 --- Quantitative adhesion measurement of gold films on plasma treated ITO --- p.62 / Chapter 4.5 --- Summary --- p.68 / Chapter Chapter 5 --- Adhesion of PFO on ITO with self-assembled monolayers as interfacial layers / Chapter 5.1 --- Introduction --- p.69 / Chapter 5.2 --- Reactions between SAMs and ITO --- p.71 / Chapter 5.3 --- Sample preparation --- p.73 / Chapter 5.4 --- Tests of alkylsilane --- p.74 / Chapter 5.4.1 --- Determination of the point of film detachment --- p.74 / Chapter 5.4.2 --- Adhesion test of PFO/alkylsilane/ITO --- p.79 / Chapter 5.4.3 --- Adhesion test of PF0/alkylsilane/Si02 --- p.91 / Chapter 5.5 --- Tests of phenylsilane --- p.104 / Chapter 5.6 --- Summary --- p.114 / Chapter Chapter 6 --- Conclusions and further studies / Chapter 6.1 --- Conclusions --- p.116 / Chapter 6.2 --- Further studies --- p.118 / References --- p.120

Magnetoresistance (MR) and doping effects have been investigated in a poly(3-hexylthiophene-2,5-diyl) (P3HT) based organic light emitting diodes. In single device of fixed composition (Au/P3HT/Al as spun and processed in air), the measured MR strongly depends on the drive conditions. The magnetoconductance (MC) varies from negative to positive (-0.4% ≤ MC ≤ 0.4%) with increasing current density, depending on which microscopic mechanism dominates. The negative MC is due to bipolaron based interactions and the positive MC to triplet-polaron based interactions (as confirmed by light emission). Oxygen doping is prevalent in P3HT devices processed in air and the effect of de-doping (by annealing above the glass transition temperature) is investigated on the MC of an Au/P3HT/Al diode. De-doping reduces the current through the device under forward bias by ~3 orders of magnitude, but increases the negative (low current) MC from a maximum of -0.5% pre-annealing to -3% post-annealing. This increased negative MC is consistent with bipolaron theory predictions based on Fermi level shifts and density of states (DoS) changes due to de-doping. The decrease in current density is explained by increased injection barriers at both electrodes also resulting from de-doping. Deliberate chemical doping of P3HT is carried out using pentacene as a hole trap centre. The trapping effect of pentacene is confirmed by reproducible and significant hole mobility-pentacene concentration behaviour, as measured by dark injection (DI) transient measurements. The enhanced carrier injection resulting from the pentacene doping also leads to increased electroluminescence (EL). The resultant MC in pentacene doped devices is strongly dependent on carrier injection and can be significantly enhanced by doping, for example from -0.2% to -0.6% depending on device and drive conditions. Throughout this thesis Lorentzian and non-Lorentzian function fitting is carried out on the measured MC, although the underlying microscopic mechanisms cannot always be discerned.

by Ng Pak Hong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 111-112). / Text in English; abstract also in Chinese. / by Ng Pak Hong. / Acknowledgments --- p.i / Abstract --- p.ii / Table of contents --- p.iv / Chapter Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- History --- p.2 / Chapter 1.2 --- Airy Theory --- p.4 / Chapter 1.2.1 --- Rainbow angle --- p.4 / Chapter 1.2.2 --- Airy's cubic wave front --- p.4 / Chapter 1.3 --- High-order rainbows --- p.7 / Chapter 1.4 --- Glare points --- p.8 / Chapter 1.5 --- Interference between overlapping rainbows --- p.10 / Chapter Chapter 2 --- HIGH-ORDER RAINBOWS --- p.17 / Chapter 2.1 --- Experiment --- p.17 / Chapter 2.2 --- Results and discussions --- p.19 / Chapter 2.2.1 --- General features --- p.19 / Chapter 2.2.2 --- Angular positions and angular widths of rainbows --- p.21 / Chapter 2.2.3 --- Rainbow intensities as functions of order number --- p.22 / Chapter 2.3 --- Vertical positions of rainbows --- p.24 / Chapter 2.4 --- Vertical spreads of rainbows --- p.26 / Chapter 2.5 --- Rainbow patterns at different values of the refractive index ..… --- p.28 / Chapter 2.6 --- Effect of eccentricity of a droplet's circumference in the equatorial plane on the rainbow angles --- p.30 / Chapter CHAPTER 3 --- GLARE POINTS --- p.56 / Chapter 3.1 --- Experiment --- p.56 / Chapter 3.2 --- Results and discussions --- p.57 / Chapter 3.2.1 --- General features --- p.57 / Chapter 3.2.2 --- Glare point position and intensity --- p.58 / Chapter A. --- Glare point position --- p.58 / Chapter B. --- Glare point intensity --- p.61 / Chapter C. --- Summary of results of glare points --- p.62 / Chapter 3.2.3 --- Fourier transform of rainbow patterns --- p.63 / Chapter Chapter 4 --- INTERFERENCE BETWEEN OVERLAPPING RAINBOWS --- p.90 / Chapter 4.1 --- Experiment --- p.90 / Chapter 4.2 --- Results and discussions --- p.91 / Chapter 4.2.1 --- General features --- p.91 / Chapter 4.2.2 --- Simulation of the interference --- p.91 / Chapter 4.2.3 --- Estimation of the droplet vibration amplitude and frequency --- p.95 / Chapter 4.3 --- Comparison with results of Lock and Woodruff --- p.96 / Chapter Chapter 5 --- CONCLUSION --- p.107 / APPENDIX A --- p.109 / References --- p.111

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