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Title: Laser-induced crystallization mechanisms in chalcogenide glass materials for advanced optical functionality.
Creator: Sisken, Laura, Richardson, Kathleen, Richardson, Martin, Shah, Lawrence, University of Central Florida
Abstract / Description: Glass-ceramics (GC) are promising candidates for gradient refractive index (GRIN) optics. These multi-phase, composite materials also exhibit improved physical properties as compared to the parent base glass resulting from the formation of a secondary crystalline phase(s). Nanocrystal phase formation in a multi-component chalcogenide glass (ChG), (GeSe2-3As2Se3)(1-x)-(PbSe)x glass where x = 0-40 has been investigated, and the role of the starting material morphology has been correlated to the...
Show moreGlass-ceramics (GC) are promising candidates for gradient refractive index (GRIN) optics. These multi-phase, composite materials also exhibit improved physical properties as compared to the parent base glass resulting from the formation of a secondary crystalline phase(s). Nanocrystal phase formation in a multi-component chalcogenide glass (ChG), (GeSe2-3As2Se3)(1-x)-(PbSe)x glass where x = 0-40 has been investigated, and the role of the starting material morphology has been correlated to the resulting composite's optical properties including refractive index, transmission, dispersion, and thermo-optic coefficient. Optical property evolution was related to the type and amount of the crystal phases formed, since through control of the local volume fraction of crystalline phase(s), the effective material properties of the composite can locally be varied. Through computational and experimental studies, tailored nanocomposites exhibiting gradient index properties have been realized. A Raman spectroscopic technique was developed as a means to spatially quantify the extent of conversion from glass to glass ceramic, and to confirm that the scale length of the local refractive index modification can be correlated to the extent of crystallization as validated by X-ray diffraction (XRD). Spatial control of the crystallization was examined by using a laser to locally modify the amount of nucleation and/or growth of crystallites in the glass. A novel technique converse to laser-induced crystallization was also developed and demonstrated that a glass ceramic could be locally re-vitrified back to a fully glassy state, through a laser-induced vitrification (LIV) method. Proof-of-concept demonstrator optics were developed using furnace and laser induced crystallization methods to validate experimental and computational approaches to modify the local volume fraction of nano-crystals. These demonstrators exhibited tailorable optical functionality as focusing optics and diffractive optics. This work paves the way for the design and fabrication of nanocomposite GRIN optics and their use in the mid-wave infrared.
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Date Issued: 2017
Identifier: CFE0006916, ucf:51684
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006916

Title: HIGH GAIN / BROADBAND OXIDE GLASSES FOR NEXT GENERATION RAMAN AMPLIFIERS.
Creator: Rivero, Clara, Stegeman, George, University of Central Florida
Abstract / Description: Interest in Raman amplification has undergone a revival due to the rapidly increasing bandwidth requirements for communications transmission, both for long haul and local area networks, and recent developments in the telecom fiber industry and diode laser technology. In contrast to rare earth doped fiber amplifiers, for which the range of wavelengths is fixed and limited, Raman gain bandwidths are larger and the operating wavelength is fixed only by the pump wavelength and the bandwidth of...
Show moreInterest in Raman amplification has undergone a revival due to the rapidly increasing bandwidth requirements for communications transmission, both for long haul and local area networks, and recent developments in the telecom fiber industry and diode laser technology. In contrast to rare earth doped fiber amplifiers, for which the range of wavelengths is fixed and limited, Raman gain bandwidths are larger and the operating wavelength is fixed only by the pump wavelength and the bandwidth of the Raman active medium. In this context, glasses are the material of choice for this application due to their relatively broad spectral response, and ability of making them into optical fiber. This dissertation summarizes findings on different oxide-based glasses that have been synthesized and characterized for their potential application as Raman gain media. Two main glass families were investigated: phosphate-based glass matrices for broadband Raman gain application and TeO2-based glasses for high Raman gain amplification. A phosphate network was preferred for the broadband application since the phosphate Raman active modes can provide amplification above 1000 cm-1, whilst TeO2-based glasses were selected for the high gain application due to their enhanced nonlinearities and polarizabilities among the other oxide-based network formers. The results summarized in this dissertation show that phosphate-based glasses can provide Raman amplification bandwidths of up to 40 THz, an improvement of almost 5 times the bandwidth of SiO2. On the other hand, tellurite-based glasses appear to be promising candidates for high gain discrete Raman applications, providing peak Raman gain coefficients of up to 50 times higher than SiO2, at 1064 nm. Although, visible spontaneous Raman scattering cross-section measurement is the most frequently used tool for estimating the strength and spectral distribution of Raman gain in materials, especially glasses, there are some issues that one needs to be aware when conducting these measurements near the absorption band edge of the material. This led to the detection of an inherent frequency-dispersion in the Raman susceptibility and a resonant enhancement phenomenon when measurements were conducted near the absorption edge of the material.
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Date Issued: 2005
Identifier: CFE0000752, ucf:46554
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000752

Title: A Study of Crystallization Behavior in Phase Separated Chalcogenide Glasses.
Creator: Buff, Andrew, Richardson, Kathleen, Sohn, Yongho, Gaume, Romain, Fargin, Evelyne, University of Central Florida
Abstract / Description: Chalcogenide glasses (ChG) are known for their wide transmission ranges in the infrared and for their high refractive indices. However, applications for ChG are often limited by their poor thermal/mechanical properties. Precipitating a secondary crystalline phase in the glass matrix can improve these properties, but too much crystallization and/or large or multiple phase crystallites can lead to a loss in infrared (IR) transmission. Controlled crystallization can be used to tune the...
Show moreChalcogenide glasses (ChG) are known for their wide transmission ranges in the infrared and for their high refractive indices. However, applications for ChG are often limited by their poor thermal/mechanical properties. Precipitating a secondary crystalline phase in the glass matrix can improve these properties, but too much crystallization and/or large or multiple phase crystallites can lead to a loss in infrared (IR) transmission. Controlled crystallization can be used to tune the properties of these glasses. This work examines the crystallization behavior in phase separated chalcogenide glasses in the GeSe2-As2Se3-PbSe glass system.Specifically, the research presented in this thesis work has investigated the crystallization behavior in the 20GeSe2-60As2Se3-20PbSe (20 PbSe) and 15GeSe2-45As2Se3-40PbSe (40 PbSe) glasses for an IR optical system operating in the 3 to 5 (&)#181;m range. While both of these glasses were found to have droplet-matrix phase separation, the morphology differed from each other in two key ways. First, the droplets seen in the 20 PbSe glass (100-130 nm) are roughly twice as big as those in the 40 PbSe glass (35-45 nm). The droplet sizes seen in the base glass directly affect the short wavelength cutoff of the two glasses where the 20 PbSe glass (1.993 (&)#181;m) has a longer wavelength cutoff than the 40 PbSe (1.319 (&)#181;m). Secondly, the 20 PbSe glass has Pb-rich droplets and the 40 PbSe glass has a Pb-rich matrix, impacting where the initial stages of crystallization are initiated. Crystallization occurs in the Pb-rich phase and affects the glass-ceramic properties differently depending on whether the Pb-rich phase is the minority phase (20 PbSe) or the majority phase (40 PbSe). When the crystallization occurs in the majority phase, it greatly affects the hardness, density, and refractive index. When the crystallization occurs in the minority phase, the hardness and density change negligibly while the refractive index still shows significant change. While both glasses show an effective index change and 3-5 (&)#181;m transmission in their base form, only the 40 PbSe maintains the transmission window after the heat-treatments used in this study.The work reported in this thesis has shown how the crystallization process can be used to develop a gradient refractive index (GRIN) component in an IR optical system. While the composition and crystallization protocols are not optimized for further transfer of the technology to commercial products, the basis of this work shows the process of developing a glass-ceramic for the application.
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Date Issued: 2016
Identifier: CFE0006271, ucf:51032
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006271

Title: Distribution of Laser Induced Heating in Multi-Component Chalcogenide Glass and its Associated Effects.
Creator: Sisken, Laura, Richardson, Kathleen, Richardson, Martin, Shah, Lawrence, University of Central Florida
Abstract / Description: Chalcogenide glasses are well known to have good transparency into the infrared spectrum. These glasses though tend to have low thresholds as compared to oxide glasses for photo-induced changes and thermally-induced changes. Material modification such as photo-induced darkening, bleaching, refractive index change, densification or expansion, ablation of crystallization have been demonstrated, and are typically induced by a thermal furnace-based heat treatment, an optical source such as a...
Show moreChalcogenide glasses are well known to have good transparency into the infrared spectrum. These glasses though tend to have low thresholds as compared to oxide glasses for photo-induced changes and thermally-induced changes. Material modification such as photo-induced darkening, bleaching, refractive index change, densification or expansion, ablation of crystallization have been demonstrated, and are typically induced by a thermal furnace-based heat treatment, an optical source such as a laser, or a combination of photo-thermal interactions. Solely employing laser-based heating has an advantage over a furnace, since one has the potential to be able to spatially modify the materials properties with much greater precision by moving either the beam or the sample.The main properties of ChG glasses investigated in this study were the light-induced and thermally-induced modification of the glass through visible microscopy, white light interferometry, and Raman spectroscopy. Additionally computational models were developed in order to aid in determining what temperature rise should be occurring under the conditions used in experiments.It was seen that ablation, photo-expansion, crystallization, and melting could occur for some of the irradiation conditions that were used. The above bandgap energy simulations appeared to overestimate the maximum temperature that should have been reached in the sample, while the below bandgap energy simulations appeared to underestimate the maximum temperature that should have been reached in the sample. Ultimately, this work produces the ground work to be able to predict and control dose, and therefore heating, to induce localized crystallization and phase change.
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Date Issued: 2014
Identifier: CFE0005261, ucf:50606
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005261

Title: FABRICATION OF INTEGRATED OPTOFLUIDIC CIRCUITS IN CHALCOGENIDE GLASS USING FEMTOSECOND LASER DIRECT WRITING.
Creator: Anderson, Troy, Richardson, Martin, University of Central Florida
Abstract / Description: Femtosecond laser direct writing (FLDW) is a versatile process that uses focused femtosecond pulses to modify the physical structure of a material, which can result in a shift of optical properties such as the linear and nonlinear refractive index. If the photon energy of the femtosecond pulses lies below the material bandgap, nonlinear absorption rather than linear absorption becomes the dominant mechanism of energy transfer to the material. In this manner, a focused femtosecond pulse train...
Show moreFemtosecond laser direct writing (FLDW) is a versatile process that uses focused femtosecond pulses to modify the physical structure of a material, which can result in a shift of optical properties such as the linear and nonlinear refractive index. If the photon energy of the femtosecond pulses lies below the material bandgap, nonlinear absorption rather than linear absorption becomes the dominant mechanism of energy transfer to the material. In this manner, a focused femtosecond pulse train can be used to fabricate functional features such as optical waveguides, diffractive optical elements, or micro-fluidic elements within the volume of a transparent medium. In this dissertation, the utility of femtosecond laser processing as a fabrication technique of optical and micro-fluidic elements in chalcogenide glasses is explored. The photo-induced modifications of optical and chemical parameters of new germanium-based Chalcogenide glasses in both bulk and thin-film form are characterized for the first time and the impact of material composition and laser fabrication parameters are discussed. The glasses are found to display an increase in volume, a decrease of the linear optical refractive index, and an increase of the nonlinear refractive index when exposed to femtosecond laser pulses. A model based on avalanche ionization and multi-photon ionization is used to describe the highly nonlinear absorption of laser light in the material and correlate the photo-induced modifications to the electron density generated during irradiation. The magnitude of the induced photo- modification is shown to be dependent on laser parameters such as laser dose and repetition rate. The fabrication of microfluidic elements through both direct ablation and the preferential etching of photo-modified regions is also explored. Finally, the integration of both optical elements and fluidic elements fabricated by FLDW into a single substrate is discussed.
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Date Issued: 2010
Identifier: CFE0002978, ucf:47965
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002978

Title: FEASIBILITY STUDY OF LIGHTWEIGHT HIGH-STRENGTH HOLLOW CORE BALSA-FRP COMPOSITE BEAMS UNDER FLEXURE.
Creator: O'Neill, Kevin, Mackie, Kevin, University of Central Florida
Abstract / Description: The United States of AmericaÃ‚Â's Military, more specifically the Army, has since the late 1990Ã‚Â's had a vested interest in the development of super-lightweight, portable, short-span composite bridge and decking components to replace aging heavy metal-alloy machine driven modular systems. The following study looks at the feasibility of using balsa wood as the structural core material in fiber reinforced polymer (FRP) wrapped hollow-core composites...
Show moreThe United States of AmericaÃ‚Â's Military, more specifically the Army, has since the late 1990Ã‚Â's had a vested interest in the development of super-lightweight, portable, short-span composite bridge and decking components to replace aging heavy metal-alloy machine driven modular systems. The following study looks at the feasibility of using balsa wood as the structural core material in fiber reinforced polymer (FRP) wrapped hollow-core composites in short-span bridge applications. The balsa provides shear resistance and the FRP the flexural resistance, resulting in extremely high strength-to-weight and strength-to-depth ratios. Several scaled short span specimens were constructed and tested using a variety of fibers and resins. In addition, a calibrated finite element model (FEM) was developed using data acquired through testing. Of the 3 FRP-matrices tested (carbon-polyurethane, glass-polyurethane, and carbon-epoxy-resin), the carbon-epoxy-resin had the stiffest cross-section and highest ultimate load achieved, although the fiber did not have the highest elastic modulus and ultimate rupture strength of the constituent materials. The carbon-polyurethane fiber had the largest elastic modulus and ultimate strength, but due to construction difficulties did not perform as well as expected. The glass-polyurethane fiber had the lowest elastic modulus and ultimate load with high strain values and performed accordingly during specimen testing. Given the constraints of self-weight, section geometry, and deflection set forth for lightweight short-span portable bridging solutions, this study demonstrates that the balsa-FRP composite systems are viable solutions; in particular, when carbon fabric is paired with balsa cores.
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Date Issued: 2010
Identifier: CFE0002997, ucf:47931
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002997

Title: Processing of Advanced Infrared Materials.
Creator: Mcgill, Daniel, Richardson, Kathleen, Gaume, Romain, Christodoulides, Demetrios, Rivero Baleine, Clara, University of Central Florida
Abstract / Description: Infrared transparent glassy and crystalline materials often have unique and complex processing requirements but are an important class of materials for such applications as optical windows, lenses, waveplates, polarizers and beam splitters. This thesis investigates two specific materials, one amorphous and one crystalline, that are candidates for use in the short and midwave-infrared and mid and longwave infrared, respectively. It is demonstrated that an innovative uniaxial sintering process,...
Show moreInfrared transparent glassy and crystalline materials often have unique and complex processing requirements but are an important class of materials for such applications as optical windows, lenses, waveplates, polarizers and beam splitters. This thesis investigates two specific materials, one amorphous and one crystalline, that are candidates for use in the short and midwave-infrared and mid and longwave infrared, respectively. It is demonstrated that an innovative uniaxial sintering process, which uses a sacrificial pressure-transmitting medium, can be used to fully densify a 70TeO2-20WO3-10La2O3 (TWL) glass powder. The characteristics of the sintered TWL glass is compared to that of a parent glass produced through a conventional melt/quench process to ascertain the impact of process-specific property changes on the resulting material. Additionally, the design, construction and characterization of a custom-made transparent Bridgman crystal growth furnace is undertaken to enable growth of highly birefringent tellurium single crystal. The key obstacles that need to be overcome to scale up the size of the grown crystals are summarized with the end goal of producing commercial grade optical elements.
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Date Issued: 2019
Identifier: CFE0007894, ucf:52761
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007894

$Volume Phase Masks in Photo-Thermo-Refractive Glass$

Title: Volume Phase Masks in Photo-Thermo-Refractive Glass.
Creator: Segall, Marc, Glebov, Leonid, Zeldovich, Boris, Dogariu, Aristide, Rahman, Talat, Bass, Michael, University of Central Florida
Abstract / Description: In many applications such as beam shaping, mode conversion, and phase encoding it is necessary to alter the spatial phase profile of a beam via a phase mask. Conventional techniques to accomplish this either involve surface relief profiling in thin films such as PMMA or refractive index modulation in bulk photorefractive crystals such as lithium niobate. These materials have been used extensively for the past several decades and perform admirably in low power conditions. However, in high...
Show moreIn many applications such as beam shaping, mode conversion, and phase encoding it is necessary to alter the spatial phase profile of a beam via a phase mask. Conventional techniques to accomplish this either involve surface relief profiling in thin films such as PMMA or refractive index modulation in bulk photorefractive crystals such as lithium niobate. These materials have been used extensively for the past several decades and perform admirably in low power conditions. However, in high power systems these materials will be destroyed, requiring a new means of producing phase masks. In this dissertation a method for producing robust phase masks in the bulk of photo-thermo-refractive glass is developed and successfully demonstrated. Three main applications of phase masks were studied in detail. The first is mode conversion, where binary phase masks convert a Gaussian beam to higher order modes. The second is beam shaping, where phase masks are used as focusing elements and for optical vortex generation. Near-theoretical conversion efficiency was achieved for all elements in these cases. The third application is aberration analysis and correction. Here the degradation of volume Bragg gratings recorded in an aberrated holographic system was modeled, with the simulations indicating that correcting elements are generally necessary for high-quality production of gratings. Corrective phase masks are designed which can selectively correct one or multiple aberrations of varying magnitudes are shown. A new type of optical element is also developed in which a phase mask is encoded into a transmitting Bragg grating. This technique combines the local phase modulation of a phase mask with the multiplexing ability of transmitting Bragg gratings, allowing for multiple phase masks to be recorded in a single element. These masks may be used at any wavelength satisfying the Bragg condition, increasing the useful wavelength regime of a single element by orders of magnitude.
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Date Issued: 2013
Identifier: CFE0005414, ucf:50431
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005414

Title: AMORPHOUS PHASE FORMATION IN MECHANICALLY ALLOYED FE-BASED SYSTEMS.
Creator: Sharma, Satyajeet, Suryanarayana, C, University of Central Florida
Abstract / Description: ABSTRACT Bulk metallic glasses have interesting combination of physical, chemical, mechanical, and magnetic properties which make them attractive for a variety of applications. Consequently there has been a lot of interest in understanding the structure and properties of these materials. More varied applications can be sought if one understands the reasons for glass formation and the methods to control them. The glass-forming ability (GFA) of alloys can be substantially increased by a proper...
Show moreABSTRACT Bulk metallic glasses have interesting combination of physical, chemical, mechanical, and magnetic properties which make them attractive for a variety of applications. Consequently there has been a lot of interest in understanding the structure and properties of these materials. More varied applications can be sought if one understands the reasons for glass formation and the methods to control them. The glass-forming ability (GFA) of alloys can be substantially increased by a proper selection of alloying elements and the chemical composition of the alloy. High GFA will enable in obtaining large section thickness of amorphous alloys. Ability to produce glassy alloys in larger section thicknesses enables exploitation of these advanced materials for a variety of different applications. The technique of mechanical alloying (MA) is a powerful non-equilibrium processing technique and is known to produce glassy (or amorphous) alloys in several alloy systems. Metallic amorphous alloys have been produced by MA starting from either blended elemental metal powders or pre-alloyed powders. Subsequently, these amorphous alloy powders could be consolidated to full density in the temperature range between the glass transition and crystallization temperatures, where the amorphous phase has a very low viscosity. This Dissertation focuses on identifying the various Fe-based multicomponent alloy systems that can be amorphized using the MA technique, studying the GFA of alloys with emphasis on improving it, and also on analyzing the effect of extended milling time on the constitution of the amorphous alloy powder produced at earlier times. The Dissertation contains seven chapters, where the lead chapter deals with the background, history and introduction to bulk metallic glasses. The following four chapters are the published/to be published work, where the criterion for predicting glass formation, effect of Niobium addition on glass-forming ability (GFA), lattice contraction on amorphization, effect of Carbon addition on GFA, and observation of mechanical crystallization in Fe-based systems have been discussed. The subsequent chapter briefly mentions about the consolidation of amorphous powders and presents results of hot pressing and spark plasma sintering on one of the alloy systems. The final chapter summarizes the Dissertation and suggests some prospective research work that can be taken up in future. The Dissertation emphasizes the glass-forming ability, i.e., the ease with which amorphization can occur. In this work the milling time required for amorphization was the indicator/measure of GFA. Although the ultimate aim of this work was to consolidate the Fe-based amorphous alloy powders into bulk so as to undertake mechanical characterization, however, it was first necessary to study the glass forming aspect in the different alloy systems. By doing this a stage has been reached, where different options are available with respect to amorphous phase-forming compositions and the knowledge to improve glass-forming ability via the mechanical alloying technique. This will be ultimately useful in the powder compaction process into various shapes and sizes at optimum pressure and temperature. The study on mechanical crystallization indicates, or in a way defines, a limit to the process of amorphization, and it was also demonstrated that this phenomenon is more common in occurrence than and not as restricted as it was earlier reported to be.
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Date Issued: 2008
Identifier: CFE0002025, ucf:47630
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002025

Title: Design of surface chemical reactivity and optical properties in glasses.
Creator: Lepicard, Antoine, Richardson, Kathleen, Seal, Sudipta, Gaume, Romain, Dussauze, Marc, Kuebler, Stephen, University of Central Florida
Abstract / Description: Thermal poling is a technique which involves the application of a strong DC electric field to a glass substrate heated below its glass transition temperature (Tg). Following the treatment, a static electric field is frozen inside the glass matrix, effectively breaking its centrosymmetry. Historically, this treatment has been used as a way to gain access to second order non-linear optical properties in glasses. However, recent efforts have shown that the treatment was responsible for...
Show moreThermal poling is a technique which involves the application of a strong DC electric field to a glass substrate heated below its glass transition temperature (Tg). Following the treatment, a static electric field is frozen inside the glass matrix, effectively breaking its centrosymmetry. Historically, this treatment has been used as a way to gain access to second order non-linear optical properties in glasses. However, recent efforts have shown that the treatment was responsible for structural changes as well as surface property modifications. Our study was focused on using this technique to tailor surface properties in oxide (borosilicate and niobium borophosphate) and chalcogenide glasses. A strong emphasis was put on trying to control all changes at the micrometric scale. After poling, property changes were assessed using a set of characterization tools: the Maker fringes technique (a Second Harmonic Generation ellipsometry technique), micro-Second Harmonic Generation ((&)#181;-SHG), vibrational spectroscopy and Secondary Ion Mass Spectroscopy (SIMS). Surface reactivity in borosilicate glasses was effectively changed while in niobium borophosphate and chalcogenide glasses, the optical properties were controlled linearly and nonlinearly. Finally, property changes were effectively controlled at the micrometric scale. This opens up new applications of thermal poling as a mean to design glass substrate for integrated photonics and lab-on-a-chip devices.
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Date Issued: 2016
Identifier: CFE0006471, ucf:51435
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006471

Title: RAMAN SPECTROSCOPY OF GLASSESWITH HIGH AND BROAD RAMAN GAIN IN THE BOSON PEAK REGION.
Creator: Guo, Yu, Schulte, Alfons, University of Central Florida
Abstract / Description: This thesis investigates Raman spectra of novel glasses and their correlation with structure for Raman gain applications. Raman gain for all-optical amplification by fibers depends significantly on the cross section for spontaneous Raman scattering allowing to compare signal strength and spectral coverage. We also investigate the relationship between glass structure and the Boson peak (enhancement of the low-frequency vibrational density of states) and report new inelastic neutron scattering...
Show moreThis thesis investigates Raman spectra of novel glasses and their correlation with structure for Raman gain applications. Raman gain for all-optical amplification by fibers depends significantly on the cross section for spontaneous Raman scattering allowing to compare signal strength and spectral coverage. We also investigate the relationship between glass structure and the Boson peak (enhancement of the low-frequency vibrational density of states) and report new inelastic neutron scattering spectra for niobium-phosphate glasses. Polarization resolved Raman spectra of glasses based on tellurite and phosphate formers have been measured from 6 – 1500 cm-1 using an excitation wavelength of 514 nm. The Tellurite glasses exhibit Raman Spectra at least 10 times more intense, are more spectrally uniform and possess spectral bandwidths more than a factor of two wider than fused silica. Assignments of the vibrational bands are presented and the compositional dependence of the spectra is discussed with respect to the molecular structure. Significantly high Boson peaks were found in the frequency range from 30-100 cm-1. The Raman gain curves were calculated from the polarized spontaneous Raman spectra. In particular, they show broad and flat band in the low frequency region (50-400 cm-1) suggesting that these glasses may be useful for Raman gain applications extending to very low frequencies. The inelastic neutron scattering spectra of the niobium-phosphate glasses display a pronounced low-frequency enhancement of the vibrational density of states. By averaging over the full accessible wavevector range we obtain an approximate spectral distribution of the vibrational modes. Through direct comparison with the Raman spectra we determine the Raman coupling function which shows a linear behavior near the Boson peak maximum. Possible mechanisms contributing to the low frequency Raman band such as disorder-induced irregular vibrational states are discussed.
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Date Issued: 2006
Identifier: CFE0001322, ucf:47021
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001322

Title: A METHODOLOGY FOR INSTRUMENTED INDENTATION STUDIES OF DEFORMATION IN BULK METALLIC GLASSES.
Creator: Sridharan, Subhaashree, Vaidyanathan, Raj, University of Central Florida
Abstract / Description: Bulk Metallic Glasses (BMGs), also known as amorphous metals, are of considerable scientific and commercial interest due to their random or chaotic structure. Given their potential use as engineering materials, there is a concomitant need to establish their mechanical properties. However, BMGs are not conveniently available in sufficient volumes (especially experimental and combinatorial compositions), making property determination via conventional tensile or compression testing problematic....
Show moreBulk Metallic Glasses (BMGs), also known as amorphous metals, are of considerable scientific and commercial interest due to their random or chaotic structure. Given their potential use as engineering materials, there is a concomitant need to establish their mechanical properties. However, BMGs are not conveniently available in sufficient volumes (especially experimental and combinatorial compositions), making property determination via conventional tensile or compression testing problematic. Instrumented indentation is ideally suited for this purpose because the testing requires only small sampling volumes and can probe multiaxial deformation characteristics at various length scales. In this technique, conducted generally on a sub-micron regime, the depth of penetration of an indenter, usually a diamond, is measured as a function of the applied load and expressed graphically as load (P) - displacement (h) curves from which a host of mechanical properties can be extracted and studied. In this work, a methodology for using instrumented indentation at nano- and micro- scales to determine the mechanical response of BMGs was developed and implemented. The implementation primarily focused on deformation in the elastic regime but included preliminary results related to the onset of inelastic deformation. The methodology developed included calibration techniques, formulations to extract the machine compliances, verifications using standards and verification for uniqueness of instrument deformation under a spherical indenter. The methodology was different for the two platforms used based on the load-depth response characteristics of the instrument. In the case of the Micro Test platform, the load-depth response of the instrument was linear. In the case of the Nano Test platform, the instrument load-depth response followed a 3/2 power law, representative of Hertzian behavior. The load-depth response of the instrument was determined by subtracting the theoretical response from the corresponding raw load-depth response obtained by elastically indenting a standard steel specimen of known modulus. The true response of the sample was then obtained by subtracting the instrument's response from the corresponding uncorrected load-depth response (raw data). An analytical model to describe the load-train compliance was developed. The methodology was verified using quartz and tungsten standards. Indentation experiments were conducted on Zr41.25Ti13.75Cu12.5Ni10Be22.5 (Vitreloy 1), Cu60Hf25Ti15, Cu60Zr30Ti10 and Fe60Co7Zr10Mo5W2B16 bulk metallic glasses using spherical indenters with diameters 2.8 mm and 100 m. The spherical geometry results in a simpler stress distribution under the indenter (when compared to a sharp geometry) and furthermore by recourse to spherical indenters the onset of plastic deformation was delayed. In the case of the Zr-based BMG, the experiments showed that the elastic response did not depend on the diameter of the indenter used indicative of the absence of residual stresses in the sample. Large scale plastic deformation was observed when the sample was indented using a smaller diameter indenter. Log scale analysis (i.e., examining the results on a log load vs. log depth response to check for deviation from Hertzian behavior) showed a deviation from a 3/2 fit indicating a deviation from elastic behavior. The onset implied a yield strength value of ~ 4 GPa, higher than the value reported in the literature (~ 2 GPa). Hence, it is believed that the first signs of plastic deformation occurred at lower loads than the predicted loads from the log scale analysis procedure and is expected to occur as discrete bursts. Discrete plastic events or "pop-ins" were observed in the load-depth indentation responses under quasistatic loading conditions, which were believed to be associated with shear band activity. An attempt was made to formulate a mathematical model based on three yield criteria (Drucker-Prager, Mohr-Coulomb and von Mises). Based on the von Mises predictions and comparable experiments on a quartz standard, it was established that the pop-ins observed were real and not an instrument artifact. Multiple load cycles following partial unload experiments showed that the pop-ins affected the subsequent indentation response. The moduli and the yield strength values obtained for the Cu-based BMGs were comparable to the values reported in the literature. There was significant scatter in the indentation data from the Fe-based BMG. Porosity and lack of 100 % compaction were believed to be the reasons for scatter in the data. The financial support of NSF through grant DMR 0314212 is gratefully acknowledged.
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Date Issued: 2006
Identifier: CFE0001442, ucf:47047
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001442

Title: A STUDY OF GENDER EQUALITY AT PRIVATE AND PUBLIC TWO-YEAR AND FOUR-YEAR FLORIDA INSTITUTIONS.
Creator: Malaret, Stacey, Tubbs, LeVester, University of Central Florida
Abstract / Description: This study sought to examine the perception of gender equality from the viewpoint of women administrators at Florida public and private two- and four-year institutions. Potential respondents were chosen from American College Personnel Association and/or National Association of Student Personnel Administrators databases. The data used for this study were obtained from 32 female administrators (50% response rate) who completed a self-administered online questionnaire, distributed to potential...
Show moreThis study sought to examine the perception of gender equality from the viewpoint of women administrators at Florida public and private two- and four-year institutions. Potential respondents were chosen from American College Personnel Association and/or National Association of Student Personnel Administrators databases. The data used for this study were obtained from 32 female administrators (50% response rate) who completed a self-administered online questionnaire, distributed to potential respondents in August and September, 2007. Collected data were entered into an SPSS database. Through data analysis, confidence intervals were reported for each survey item. Comparable means were studied for each of the six independent variables used in the survey. A broad array of gender equality information was disclosed in the data and literature. This information provided a basis for further research topics on perception on gender equality in higher education administration.
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Date Issued: 2007
Identifier: CFE0001849, ucf:47375
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001849

Title: EVALUATION OF THE PHOTO-INDUCED STRUCTURAL MECHANISMS IN CHALCOGENIDE GLASS MATERIALS.
Creator: Lopez, Cedric, Richardson, Kathleen, University of Central Florida
Abstract / Description: Chalcogenide glasses and their use in a wide range of optical, electronic and memory applications, has created a need for a more thorough understanding of material property variation as a function of composition and in geometries representative of actual devices. This study evaluates compositional dependencies and photo-induced structural mechanisms in As-S-Se chalcogenide glasses. An effective fabrication method for the reproducible processing of bulk chalcogenide materials has been...
Show moreChalcogenide glasses and their use in a wide range of optical, electronic and memory applications, has created a need for a more thorough understanding of material property variation as a function of composition and in geometries representative of actual devices. This study evaluates compositional dependencies and photo-induced structural mechanisms in As-S-Se chalcogenide glasses. An effective fabrication method for the reproducible processing of bulk chalcogenide materials has been demonstrated and an array of tools developed, for the systematic characterization of the resulting material's physical and optical properties. The influence of compositional variation on the physical properties of 13 glasses within the As-S-Se system has been established. Key structural and optical differences have been observed and quantified between bulk glasses and their corresponding as-deposited films. The importance of annealing and aging of the film material and the impact on photosentivity and long term behavior important to subsequent device stability have been evaluated. Photo-induced structures have been created in the thin films using bandgap cw and sub-bandgap femtosecond laser sources and the exposure conditions and their influence on the post-exposure material properties, have been found to have different limitations and driving mechanisms. These mechanisms largely depend on both structural and/or electronic defects, whether initially present in the chalcogenide material or created upon exposure. These defect processes, largely studied previously in individual binary material systems, have now been shown to be consistently present, but varying in extent, across the ternary glass compositions and exposure conditions examined. We thus establish the varying photo-response of these defects as being the major reason for the optical variations observed. Nonlinear optical material properties, as related to the multiphoton processes used in our exposure studies, have been modeled and a tentative explanation for their variation in the context of composition and method of evaluation is presented.
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Date Issued: 2004
Identifier: CFE0000196, ucf:46177
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000196

Title: NONLINEAR FEMTOSECOND NEAR INFRARED LASER STRUCTURING IN OXIDE GLASSES.
Creator: Royon, Arnaud, Richardson, Martin, University of Central Florida
Abstract / Description: Three-dimensional femtosecond laser structuring has a growing interest because of its ease of implementation and the numerous possible applications in the domain of photonic components. Structures such as waveguides, diffraction gratings, optical memories or photonic crystals can be fabricated thanks to this technique. Its use with oxide glasses is promising because of several advantages; they are resistant to flux and ageing, their chemical composition can easily be changed to fit the well...
Show moreThree-dimensional femtosecond laser structuring has a growing interest because of its ease of implementation and the numerous possible applications in the domain of photonic components. Structures such as waveguides, diffraction gratings, optical memories or photonic crystals can be fabricated thanks to this technique. Its use with oxide glasses is promising because of several advantages; they are resistant to flux and ageing, their chemical composition can easily be changed to fit the well-defined requirements of an application. They can already be found in Raman amplifiers, optical fibers, fiber lasers, and other devices. This thesis is based on two axes. The first axis consists in characterizing the linear and nonlinear optical properties of bulk vitreous materials in order to optimize their composition with a particular application in view. Within this context, the nonlinear optical properties, their physical origins (electronic and nuclear) as well as their characteristic response times (from a few femtoseconds to a few hundreds of picoseconds) are described within the Born-Oppenheimer approximation. Fused silica and several sodium-borophosphate glasses containing different concentrations in niobium oxide have been studied. Results show that the nonlinear optical properties of fused silica are mainly from electronic origin, whereas in the sodium-borophosphate glasses, the contribution from nuclear origin becomes predominant when the concentration of niobium oxide exceeds 30%. The second axis is based on the structuring of materials. Three commercially available fused silica samples presenting different fabrication conditions (therefore distinct impurity levels) and irradiated with a near infrared femtosecond laser have been studied. The laser induced defects have been identified by means of several spectroscopic techniques. They show the formation of color centers as well as a densification inside the irradiated area. Their linear refractive index and nonlinear third-order susceptibility properties have been measured. Moreover, the structuring of fused silica at the subwavelength scale into "nanogratings" is observed and the form of birefringence induced by these structures is discussed. In addition to the fused silica samples, several oxide glasses presenting very distinct chemical compositions have been studied. A sodium-borophosphate glass containing niobium oxide exhibits micro-cracks and nano-crystallites following irradiation. A silicate glass with or without a silver component reveals fluorescent rings or "nanograting" structures. A zinc phosphate glass containing silver also presents fluorescent ring structures, with a size of the order of 80 nm, well below the diffraction limit. Pump-probe microscope techniques have been performed on this glass to investigate the laser-glass interaction. The absorption mechanism is determined to be four-photon absorption. The generated free electron density is ~ 1017 cm-3, which suggests the conclusion that an electron gas rather than a plasma is formed during the laser irradiation.
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Date Issued: 2009
Identifier: CFE0002666, ucf:48200
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002666

Title: STRUCTURAL EVOLUTION IN MECHANICALLY ALLOYED FE-BASED POWDER SYSTEMS.
Creator: Patil, Umesh, Suryanarayan, Challapalli, University of Central Florida
Abstract / Description: A systematic study of iron-based binary and multi-component alloys was undertaken to study the structural evolution in these powders as a function of milling time during mechanical alloying. Blended elemental powders of Fe100-XBX (where x = 5, 10, 17, 20, 22, 25, 37.5 and 50 at. %) and a bulk metallic glass (BMG) composition (Fe60Co8Zr10Mo5W2B15) were subjected to mechanical alloying in a SPEX 8000 mixer mill. X-ray diffraction technique was employed to study the phase evolution, crystallite...
Show moreA systematic study of iron-based binary and multi-component alloys was undertaken to study the structural evolution in these powders as a function of milling time during mechanical alloying. Blended elemental powders of Fe100-XBX (where x = 5, 10, 17, 20, 22, 25, 37.5 and 50 at. %) and a bulk metallic glass (BMG) composition (Fe60Co8Zr10Mo5W2B15) were subjected to mechanical alloying in a SPEX 8000 mixer mill. X-ray diffraction technique was employed to study the phase evolution, crystallite size, lattice strain and also to determine the crystal structure(s) of the phases. Depending on the milling time, formation of supersaturated solid solutions, intermetallics, and amorphous phases was noted in the binary Fe-B powder mixtures. A maximum of about 22 at. % B was found to dissolve in Fe in the solid state, and formation of FeB and Fe2B intermetallics was noted in some of the powder blends. However, an interesting observation that was made, for the first time, related to the formation of a crystalline phase on continued milling of the amorphous powder in the BMG composition. This phenomenon, termed mechanical crystallization, has been explored. Reasons for the mechanical crystallization of the amorphous powder using the X-ray diffraction and electron microscopy methods have been discussed. External heat treatments of the milled powder were also conducted to study the complete crystallization behavior of the amorphous phase. Preliminary attempts were made to consolidate the milled BMG powder to bulk shape by hot isostatic pressing (HIP) and magnetic compaction techniques. Full densification was not achieved. Nanoindentation and microhardness tests were performed to characterize the mechanical properties of the glassy alloy. Nanoindentation results gave an elastic modulus of 59 GPa, lower than the expected value of 184 GPa; due to the presence of porosity in the consolidated sample. Optimization of the consolidation parameters is required to achieve a fully dense material.
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Date Issued: 2005
Identifier: CFE0000868, ucf:46649
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000868

Title: ULTRASHORT LASER PULSE INTERACTION WITH PHOTO-THERMO-REFRACTIVE GLASS.
Creator: Siiman, Leo, Glebov, Leonid, University of Central Florida
Abstract / Description: Photo-thermo-refractive (PTR) glass is an ideal photosensitive material for recording phase volume holograms. It is a homogeneous multi-component silicate glass that demonstrates all the advantages of optical glass: thermal stability, high laser damage threshold, and a wide transparency range. Moreover the ability to record phase patterns (i.e. spatial refractive index variations) into PTR glass has resulted in the fabrication of volume holograms with diffraction efficiency greater than 99%....
Show morePhoto-thermo-refractive (PTR) glass is an ideal photosensitive material for recording phase volume holograms. It is a homogeneous multi-component silicate glass that demonstrates all the advantages of optical glass: thermal stability, high laser damage threshold, and a wide transparency range. Moreover the ability to record phase patterns (i.e. spatial refractive index variations) into PTR glass has resulted in the fabrication of volume holograms with diffraction efficiency greater than 99%. The conventional method of recording a hologram in PTR glass relies on exposure to continuous-wave ultraviolet laser radiation. In this dissertation the interaction between infrared ultrashort laser pulses and PTR glass is studied. It is shown that photosensitivity in PTR glass can be extended from the UV region to longer wavelengths (near-infrared) by exposure to ultrashort laser pulses. It is found that there exists a focusing geometry and laser pulse intensity interval for which photoionization and refractive index change in PTR glass after thermal development occur without laser-induced optical damage. Photoionization of PTR glass by IR ultrashort laser pulses is explained in terms of strong electric field ionization. This phenomenon is used to fabricate phase optical elements in PTR glass. The interaction between ultrashort laser pulses and volume holograms in PTR glass is studied in two laser intensity regimes. At intensities below ~10^12 W/cm^2 properties such as diffraction efficiency, angular divergence, selectivity, and pulse front tilt are shown to agree with the theory of linear diffraction for broad spectral width lasers. A volume grating pair arrangement is shown to correct the laser pulse distortions arising from pulse front tilt and angular divergence. At higher intensities of irradiation, nonlinear generation and diffraction of third harmonic is observed for three types of interactions: sum-frequency generation, front-surface THG generation, and THG due to phase-matching with a grating formed by modulation of the nonlinear refractive index of PTR glass.
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Date Issued: 2008
Identifier: CFE0002349, ucf:47804
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002349

$Holographic optical elements for visible light applications in photo-thermo-refractive glass$

Title: Holographic optical elements for visible light applications in photo-thermo-refractive glass.
Creator: Kompan, Fedor, Glebov, Leonid, Schulzgen, Axel, Richardson, Kathleen, Rahman, Talat, University of Central Florida
Abstract / Description: This dissertation reports on design and fabrication of various optical elements in Photo-thermo-refractive (PTR) glass. An ability to produce complex holographic optical elements (HOEs) for the visible spectral region appears very beneficial for variety of applications, however, it is limited due to photosensitivity of the glass confined within the UV region. First two parts of this dissertation present two independent approaches to the problem of holographic recording using visible radiation...
Show moreThis dissertation reports on design and fabrication of various optical elements in Photo-thermo-refractive (PTR) glass. An ability to produce complex holographic optical elements (HOEs) for the visible spectral region appears very beneficial for variety of applications, however, it is limited due to photosensitivity of the glass confined within the UV region. First two parts of this dissertation present two independent approaches to the problem of holographic recording using visible radiation. The first method involves modification of the original PTR glass rendering it photosensitive to radiation in the visible spectral region and, thus, making possible the recording of holograms in PTR glass with visible radiation. The mechanism of photoionization in this case is based on an excited state absorption upconversion process in the glass when doped with Tb3+. By contrast, the second approach uses the original Ce3+ doped PTR glass and introduces a new modified technique for hologram formation that allows for holographic recording with visible light. Complex HOEs including holographic lenses and holographic curved mirrors were fabricated in PTR glass with visible light using both techniques. The third part of the dissertation takes a step in a different direction and discusses the development of the methods for fabrication of phase masks in PTR glass. A method for relatively straightforward and inexpensive fabrication of phase masks with the aid of a Digital Micromirror Device is presented. This method enabled to produce phase masks containing complex greyscale phase distributions for generation of vortex (helical) beams. A phase mask can be holographically encoded into a transmission Bragg grating where a holographic phase mask (HPM) is formed. HPM has an advantage over a regular phase mask of being capable of multi-wavelength operation. All optical elements recorded in PTR glass preserve the advantages peculiar to VBGs recorded in PTR glass such as stability to heating and illumination with high-power laser beams.
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Date Issued: 2019
Identifier: CFE0007665, ucf:52480
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007665

Title: Modeling of Thermal Properties of Fiber Glass Polyester Resin Composite Under Thermal Degradation Condition.
Creator: Tsoi, Marvin, Chen, Ruey-Hung, Gou, Jihua, Ilie, Marcel, University of Central Florida
Abstract / Description: Composites, though used in a variety of applications from chairs and office supplies to structures of U.S. Navy ships and aircrafts, are not all designed to hold up to extreme heat flux and high temperature. Fiber-reinforced polymeric composites (FRPC) have been proven to provide the much needed physical and mechanical properties under fire exposure. FRPC notable features are its combination of high specific tensile strength, low weight, along with good corrosion and fatigue resistance....
Show moreComposites, though used in a variety of applications from chairs and office supplies to structures of U.S. Navy ships and aircrafts, are not all designed to hold up to extreme heat flux and high temperature. Fiber-reinforced polymeric composites (FRPC) have been proven to provide the much needed physical and mechanical properties under fire exposure. FRPC notable features are its combination of high specific tensile strength, low weight, along with good corrosion and fatigue resistance. However FRPC are susceptible to thermal degradation and decomposition, which yields flammable gas, and are thus highly combustible. This property restricts polymeric material usage.This study developed a numerical model that simulated the degradation rate and temperature profiles of a fiber-reinforced polyester resin composite exposed to a constant heat flux and hydrocarbon fire in a cone calorimeter. A numerical model is an essential tool because it gives the composite designer the ability to predict results in a time and cost efficient manner. The goal of this thesis is to develop a numerical model to simulate a zonal-layer polyester resin and fiber-glass mat composite and then validate the model with experimental results from a cone calorimeter. By inputting the thermal properties of the layered composite of alternating polymer and polymer-infused glass fiber mat layers, the numerical model is one step closer to representing the experimental data from the cone calorimeter test. The final results are achieved through adding a simulated heat flux from the pilot ignition of the degraded gas of the polyester resin. The results can be coupled into a mechanical model, which may be separately constructed for future study on the mechanical strength of composites under fire conditions.
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Date Issued: 2011
Identifier: CFE0004171, ucf:49076
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004171

$Metrology of Volume Chirped Bragg Gratings Recorded in Photo-Thermo-Refractive Glass for Ultrashort Pulse Stretching and Compressing$

Title: Metrology of Volume Chirped Bragg Gratings Recorded in Photo-Thermo-Refractive Glass for Ultrashort Pulse Stretching and Compressing.
Creator: Lantigua, Christopher, Glebov, Leonid, Zeldovich, Boris, Schulzgen, Axel, University of Central Florida
Abstract / Description: Chirped Bragg gratings (CBGs) recorded in photo-thermo-refractive (PTR) glass provide a very efficient and robust way to stretch and compress ultra-short laser pulses. These gratings offer the ability to stretch pulses from hundreds of femtoseconds, to the order of 1 ns and then re-compress them. However, in order to achieve pulse stretching of this magnitude, 100 mm thick CBGs are needed. Using these CBGs to both stretch, and re-compress the pulse thus requires propagation through 200 mm of...
Show moreChirped Bragg gratings (CBGs) recorded in photo-thermo-refractive (PTR) glass provide a very efficient and robust way to stretch and compress ultra-short laser pulses. These gratings offer the ability to stretch pulses from hundreds of femtoseconds, to the order of 1 ns and then re-compress them. However, in order to achieve pulse stretching of this magnitude, 100 mm thick CBGs are needed. Using these CBGs to both stretch, and re-compress the pulse thus requires propagation through 200 mm of optical glass. This therefore demands perfect control of the glass homogeneity, as well as the holographic recording process of the CBG. In this thesis, we present a study of the CBG parameters that lead to distortions in the quality of diffracted beams. We first present the challenges associated with measuring the quality of these beams and we show that such measurements are not easily achieved using commercial systems that rely on the ISO standard M2 method. Thus, we introduce a new metric of beam quality, which we have coined S2, that is a combination of both the M2 and power in the bucket metrics. Subsequently, we investigate the influence of the CBG parameters on the quality of diffracted beams. In particular, we examine the impact of small optical heterogeneities known as striae, as well as the impact of the optically and thermally induced distortions in the grating. We then use this data to improve the fabrication and characterization of 100 mm long CBGs.Finally, we characterize the performance of CBGs recorded in PTR for stretching and compression of femtosecond pulses using a custom autocorrelation system. We present data on high quality 100 mm long CBGs and an analysis on the correlation between beam quality and the final pulse duration after stretching and re-compressing the pulse.
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Date Issued: 2013
Identifier: CFE0004876, ucf:49680
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004876

glass (4)	+ -
composite (3)	+ -
Raman spectroscopy (2)	+ -
chalcogenide (2)	+ -
femtosecond (2)	+ -

oxide glasses (2)	+ -
photosensitive glass (2)	+ -
volume Bragg gratings (2)	+ -
ANSYS (1)	+ -
Amorphous (1)	+ -
Boson peak (1)	+ -
Bridgman (1)	+ -
Bulk Metallic Glass (1)	+ -
Bulk Metallic Glasses (1)	+ -
Bulk metallic glass (1)	+ -
Chalcogenide (1)	+ -
Chalcogenide Glass (1)	+ -
Chirped Bragg Gratings (1)	+ -
Crystallization (1)	+ -
Effect of Nb and carbon. (1)	+ -
Fe-B alloy (1)	+ -
Femtosecond (1)	+ -
Femtosecond laser (1)	+ -
Glass (1)	+ -
Glass Ceramic (1)	+ -
Glass forming ability (1)	+ -
Glass-ceramic (1)	+ -
Gradient Refractive Index (1)	+ -
Growth (1)	+ -
High Power Beam Combining (1)	+ -

ETD Collection (23)	+ -
Honors Collection (1)	+ -

University of Central Florida (24)	+ -
Richardson, Kathleen (7)	+ -
Glebov, Leonid (5)	+ -
Richardson, Martin (4)	+ -
Zeldovich, Boris (4)	+ -

Gaume, Romain (3)	+ -
Rahman, Talat (3)	+ -
Schulte, Alfons (2)	+ -
Schulzgen, Axel (2)	+ -
Shah, Lawrence (2)	+ -
Sisken, Laura (2)	+ -
Anderson, Troy (1)	+ -
Andrusyak, Oleksiy (1)	+ -
Bass, Michael (1)	+ -
Buff, Andrew (1)	+ -
Chen, Ruey-Hung (1)	+ -
Chow, Lee (1)	+ -
Christodoulides, Demetrios (1)	+ -
Dogariu, Aristide (1)	+ -
Dussauze, Marc (1)	+ -
Fargin, Evelyne (1)	+ -
Gordon, Ali (1)	+ -
Gou, Jihua (1)	+ -
Graham, Zachary (1)	+ -
Guo, Yu (1)	+ -
Heinrich, Helge (1)	+ -
Ilie, Marcel (1)	+ -
Kompan, Fedor (1)	+ -
Kuebler, Stephen (1)	+ -
Lantigua, Christopher (1)	+ -

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