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Title: Cascaded plasmon resonances for enhanced nonlinear optical response.
Creator: Toroghi, Seyfollah, Kik, Pieter, Vanstryland, Eric, Kuebler, Stephen, Hagan, David, Belfield, Kevin, University of Central Florida
Abstract / Description: The continued development of integrated photonic devices requires low-power, small volume all-optical modulators. The weak nonlinear optical response of conventional optical materials requires the use of high intensities and large interaction volumes in order to achieve significant light modulation, hindering the miniaturization of all-optical switches and the development of lightweight transmission optics with nonlinear optical response. These challenges may be addressed using plasmonic...
Show moreThe continued development of integrated photonic devices requires low-power, small volume all-optical modulators. The weak nonlinear optical response of conventional optical materials requires the use of high intensities and large interaction volumes in order to achieve significant light modulation, hindering the miniaturization of all-optical switches and the development of lightweight transmission optics with nonlinear optical response. These challenges may be addressed using plasmonic nanostructures due to their unique ability to confine and enhance electric fields in sub-wavelength volumes. The ultrafast nonlinear response of free electrons in such plasmonic structures and the fast thermal nonlinear optical response of metal nanoparticles, as well as the plasmon enhanced nonlinear Kerr-type response of the host material surrounding the nanostructures could allow ultrafast all-optical modulation with low modulation energy. In this thesis, we investigate the linear and nonlinear optical response of engineered effective media containing coupled metallic nanoparticles. The fundamental interactions in systems containing coupled nanoparticles with size, shape, and composition dissimilarity, are evaluated analytically and numerically, and it is demonstrated that under certain conditions the achieved field enhancement factors can exceed the single-particle result by orders of magnitude in a process called cascaded plasmon resonance. It is demonstrated that these conditions can be met in systems containing coupled nanospheres, and in systems containing non-spherical metal nanoparticles that are compatible with common top-down nanofabrication methods such as electron beam lithography and nano-imprint lithography. We show that metamaterials based on such cascaded plasmon resonance structures can produce enhanced nonlinear optical refraction and absorption compared to that of conventional plasmonic nanostructures. Finally, it is demonstrated that the thermal nonlinear optical response of metal nanoparticles can be enhanced in carefully engineered heterogeneous nanoparticle clusters, potentially enabling strong and fast thermal nonlinear optical response in system that can be produced in bulk through chemical synthesis.
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Date Issued: 2014
Identifier: CFE0005556, ucf:50272
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005556

Title: Nonlinear integrated photonics on silicon and gallium arsenide substrates.
Creator: Ma, Jichi, Fathpour, Sasan, Hagan, David, Li, Guifang, Peale, Robert, University of Central Florida
Abstract / Description: Silicon photonics is nowadays a mature technology and is on the verge of becoming a blossoming industry. Silicon photonics has also been pursued as a platform for integrated nonlinear optics based on Raman and Kerr effects. In recent years, more futuristic directions have been pursued by various groups. For instance, the realm of silicon photonics has been expanded beyond the well-established near-infrared wavelengths and into the mid-infrared (3 (-) 5 (&)#181;m). In this wavelength range,...
Show moreSilicon photonics is nowadays a mature technology and is on the verge of becoming a blossoming industry. Silicon photonics has also been pursued as a platform for integrated nonlinear optics based on Raman and Kerr effects. In recent years, more futuristic directions have been pursued by various groups. For instance, the realm of silicon photonics has been expanded beyond the well-established near-infrared wavelengths and into the mid-infrared (3 (-) 5 (&)#181;m). In this wavelength range, the omnipresent hurdle of nonlinear silicon photonics in the telecommunication band, i.e., nonlinear losses due to two-photon absorption, is inherently nonexistent. With the lack of efficient light-emission capability and second-order optical nonlinearity in silicon, heterogeneous integration with other material systems has been another direction pursued. Finally, several approaches have been proposed and demonstrated to address the energy efficiency of silicon photonic devices in the near-infrared wavelength range. In this dissertation, theoretical and experimental works are conducted to extend applications of integrated photonics into mid-infrared wavelengths based on silicon, demonstrate heterogeneous integration of tantalum pentoxide and lithium niobate photonics on silicon substrates, and study two-photon photovoltaic effect in gallium arsenide and plasmonic-enhanced structures.Specifically, performance and noise properties of nonlinear silicon photonic devices, such as Raman lasers and optical parametric amplifiers, based on novel and reliable waveguide technologies are studied. Both near-infrared and mid-infrared nonlinear silicon devices have been studied for comparison. Novel tantalum-pentoxide- and lithium-niobate-on-silicon platforms are developed for compact microring resonators and Mach-Zehnder modulators. Third- and second-harmonic generations are theoretical studied based on these two platforms, respectively. Also, the two-photon photovoltaic effect is studied in gallium arsenide waveguides for the first time. The effect, which was first demonstrated in silicon, is the nonlinear equivalent of the photovoltaic effect of solar cells and offers a viable solution for achieving energy-efficient photonic devices. The measured power efficiency achieved in gallium arsenide is higher than that in silicon and even higher efficiency is theoretically predicted with optimized designs. Finally, plasmonic-enhanced photovoltaic power converters, based on the two-photon photovoltaic effect in silicon using subwavelength apertures in metallic films, are proposed and theoretically studied.
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Date Issued: 2014
Identifier: CFE0005373, ucf:50441
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005373

Title: Optically isotropic liquid crystals for display and photonic applications.
Creator: Yan, Jin, Wu, Shintson, Zeldovich, Boris, Schoenfeld, Winston, Fang, Jiyu, University of Central Florida
Abstract / Description: For the past few decades, tremendous progress has been made on liquid crystal display (LCD) technologies in terms of stability, resolution, contrast ratio, and viewing angle. The remaining challenge is response time. The state-of-the-art response time of a nematic liquid crystal is a few milliseconds. Faster response time is desirable in order to reduce motion blur and to realize color sequential display using RGB LEDs, which triples the optical efficiency and resolution density. Polymer...
Show moreFor the past few decades, tremendous progress has been made on liquid crystal display (LCD) technologies in terms of stability, resolution, contrast ratio, and viewing angle. The remaining challenge is response time. The state-of-the-art response time of a nematic liquid crystal is a few milliseconds. Faster response time is desirable in order to reduce motion blur and to realize color sequential display using RGB LEDs, which triples the optical efficiency and resolution density. Polymer-stabilized blue phase liquid crystal (PS-BPLC) is a strong candidate for achieving fast response time because its self-assembled cubic structure greatly reduces the coherence length. The response time is typically in the submillisecond range and can even reach microsecond under optimized conditions. Moreover, it exhibit several attractive features, such as no need for surface alignment layer, intrinsic wide viewing angle, and cell gap insensitivity if an in-plane-switching (IPS) cell is employed. In this dissertation, recent progresses in polymer-stabilized blue phases, or more generally optically-isotropic liquid crystals, are presented. Potential applications in display and photonic devices are also demonstrated.In Chapter 1, a brief introduction of optically isotropic liquid crystals is given. In Chapter 2, we investigate each component of polymer-stabilized blue phase materials and provide guidelines for material preparation and optimization. In Chapter 3, the electro-optical properties of PS-BPLCs, including electric-field-induced birefringence and dynamic behaviors are characterized. Theoretical models are proposed to explain the physical phenomena. Good agreements between experimental data and models are obtained. The proposed models also provide useful guidelines for both material and device optimizations. Four display and photonic devices using PS-BPLCs are demonstrated in Chapter 4. First, by red-shifting the Bragg reflection and using circular polarizers, we reduce the LCD driving voltage by 35% as compared to a short-pitch BPLC while maintaining high contrast ratio and submillisecond response time. Second, a turning film which is critically needed for widening the viewing angle of a vertical field switching (VFS) BPLC mode is designed. With this film, the viewing angle of VFS is widened to (&)#177; 80(&)deg; in horizontal direction and (&)#177; 50(&)deg; in vertical direction. Without this turning film, the viewing angle is only (&)#177;30(&)deg;, which is too narrow for most applications. Third, a reflective BPLC display with vivid colors, submillisecond response time, and natural grayscales is demonstrated for the first time. The proposed BPLC reflective display opens a new gateway for 3D reflective displays; it could make significant impact to display industry. Finally, we demonstrate a tunable phase grating with a high diffraction efficiency of 40% and submillisecond response time. This tunable grating exhibits great potential for photonic and display applications, such as optical interconnects, beam steering, and projection displays.
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Date Issued: 2013
Identifier: CFE0005279, ucf:50551
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005279

Title: Optical and Magnetic properties of nanostructures.
Creator: Nayyar, Neha, Rahman, Talat, Stolbov, Sergey, Ishigami, Marsahir, Hernandez, Florencio, University of Central Florida
Abstract / Description: In this thesis, Density Functional Theory and Time-Dependent Density-Functional Theory approaches are applied to study the optical and magnetic properties of several types of nanostructures. In studies of the optical properties we mainly focused on the plasmonic and excitonic effects in pure and transition metal-doped noble metal nanochains and their conglomerates. In the case of pure noble metal chains, it was found that the (collective) plasmon mode is pronounceable when the number of atoms...
Show moreIn this thesis, Density Functional Theory and Time-Dependent Density-Functional Theory approaches are applied to study the optical and magnetic properties of several types of nanostructures. In studies of the optical properties we mainly focused on the plasmonic and excitonic effects in pure and transition metal-doped noble metal nanochains and their conglomerates. In the case of pure noble metal chains, it was found that the (collective) plasmon mode is pronounceable when the number of atoms in the chain is larger than 5. The plasmon energy decreases with further with increasing number of atoms (N) and is almost N-independent when N is larger than 20. In the case of coupled pure chains it was found that the plasmon energy grows as square root of the number of chains, and reaches the visible light energy 1.8eV for the case of three parallel chains. Doping of pure Au chains with transition-metal atoms leads in many cases to formation of additional plasmon peaks close in energy to the undoped chain peak. This peak comes from the local charge oscillations around the potential minima created by the impurity atom. The effect is especially pronounced for Ni-doped chains. In the multiple-chain case, we find an unusual hybridization of the two different (local and collective) plasmon modes. Changing the chain size and chemical composition in the array can be used to tune the absorption properties of nanochains. The case of coupled finite (plasmonic) and infinite (semiconductor, excitonic) chains was also analyzed. We find that one can get significant exciton-plasmon coupling, including hybridized modes and energy transfer between these excitations, in the case of doped chains. The impurity atoms are found to work as attraction centers for excitons. This can be used to transform the exciton energy into local plasmon oscillations with consequent emission at desired point (at which the impurity is located). In a related study the optical properties of single layer MoS2 was analyzed with a focus on the possibility of ultrafast emission, In particular, it was found that the system can emit in femto-second regime under ultrafast laser pulse excitations. Finally, we have studied the magnetic properties of FeRh nanostructures to probe whether there is an antiferromagnetic to ferromagnetic transition as a function of the ratio of Fe and Rh atoms, as in the bulk alloy.. Surprisingly, the ferromagnetic phase is found to be much more stable for these nanostructures as compared to the bulk, which suggests that band-type effects may be responsible for this transition in the bulk, i.e. the transition cannot be described in terms of modification of the Heisenberg model parameters.
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Date Issued: 2014
Identifier: CFE0005221, ucf:50650
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005221

Title: CHEMICAL STRUCTURE - NONLINEAR OPTICAL PROPERTY RELATIONSHIPS FOR A SERIES OF TWO-PHOTON ABSORBING FLUORENE MOLECULES.
Creator: Hales, Joel McCajah, Van Stryland, Eric W., University of Central Florida
Abstract / Description: This dissertation reports on the investigation of two-photon absorption (2PA) in a series of fluorenyl molecules. Several current and emerging technologies exploit this optical nonlinearity including two-photon fluorescence imaging, three-dimensional microfabrication, site-specific photodynamic cancer therapy and biological caging studies. The two key features of this nonlinearity which make it an ideal candidate for the above applications are its quadratic dependence on the incident...
Show moreThis dissertation reports on the investigation of two-photon absorption (2PA) in a series of fluorenyl molecules. Several current and emerging technologies exploit this optical nonlinearity including two-photon fluorescence imaging, three-dimensional microfabrication, site-specific photodynamic cancer therapy and biological caging studies. The two key features of this nonlinearity which make it an ideal candidate for the above applications are its quadratic dependence on the incident irradiance and the improved penetration into absorbing media that it affords. As a consequence of the burgeoning field which exploits 2PA, it is a goal to find materials that exhibit strong two-photon absorbing capabilities. Organic materials are promising candidates for 2PA applications because their material properties can be tailored through molecular engineering thereby facilitating optimization of their nonlinear optical properties. Fluorene derivatives are particularly interesting since they possess high photochemical stability for organic molecules and are generally strongly fluorescent. By systematically altering the structural properties in a series of fluorenyl molecules, we have determined how these changes affect their two-photon absorbing capabilities. This was accomplished through characterization of both the strength and location of their 2PA spectra. In order to ensure the validity of these results, three separate nonlinear characterization techniques were employed: two-photon fluorescence spectroscopy, white-light continuum pump-probe spectroscopy, and the Z-scan technique. In addition, full linear spectroscopic characterization was performed on these molecules along with supplementary quantum chemical calculations to obtain certain molecular properties that might impact the nonlinearity. Different designs in chemical architecture allowed investigation of the effects of symmetry, solvism, donor-acceptor strengths, conjugation length, and multi-branched geometries on the two-photon absorbing properties of these molecules. In addition, the means to enhance 2PA via intermediate state resonances was investigated. To provide plausible explanations for the experimentally observed trends, a conceptually simple three level model was employed. The subsequent correlations found between chemical structure and the linear and nonlinear optical properties of these molecules provided definitive conclusions on how to properly optimize their two-photon absorbing capabilities. The resulting large nonlinearities found in these molecules have already shown promise in a variety of the aforementioned applications.
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Date Issued: 2004
Identifier: CFE0000005, ucf:46103
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000005

Title: HYBRID PHOTONIC SIGNAL PROCESSING.
Creator: Ghauri, Farzan, Riza, Nabeel, University of Central Florida
Abstract / Description: This thesis proposes research of novel hybrid photonic signal processing systems in the areas of optical communications, test and measurement, RF signal processing and extreme environment optical sensors. It will be shown that use of innovative hybrid techniques allows design of photonic signal processing systems with superior performance parameters and enhanced capabilities. These applications can be divided into domains of analog-digital hybrid signal processing applications and free-space-...
Show moreThis thesis proposes research of novel hybrid photonic signal processing systems in the areas of optical communications, test and measurement, RF signal processing and extreme environment optical sensors. It will be shown that use of innovative hybrid techniques allows design of photonic signal processing systems with superior performance parameters and enhanced capabilities. These applications can be divided into domains of analog-digital hybrid signal processing applications and free-space--fiber-coupled hybrid optical sensors. The analog-digital hybrid signal processing applications include a high-performance analog-digital hybrid MEMS variable optical attenuator that can simultaneously provide high dynamic range as well as high resolution attenuation controls; an analog-digital hybrid MEMS beam profiler that allows high-power watt-level laser beam profiling and also provides both submicron-level high resolution and wide area profiling coverage; and all optical transversal RF filters that operate on the principle of broadband optical spectral control using MEMS and/or Acousto-Optic tunable Filters (AOTF) devices which can provide continuous, digital or hybrid signal time delay and weight selection. The hybrid optical sensors presented in the thesis are extreme environment pressure sensors and dual temperature-pressure sensors. The sensors employ hybrid free-space and fiber-coupled techniques for remotely monitoring a system under simultaneous extremely high temperatures and pressures.
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Date Issued: 2007
Identifier: CFE0001983, ucf:47423
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001983

Title: MESHFREE APPROXIMATION METHODS FOR FREE-FORM OPTICAL SURFACES WITH APPLICATIONS TO HEAD-WORN DISPLAYS.
Creator: Cakmakci, Ozan, Rolland, Jannick, University of Central Florida
Abstract / Description: Compact and lightweight optical designs achieving acceptable image quality, field of view, eye clearance, eyebox size, operating across the visible spectrum, are the key to the success of next generation head-worn displays. The first part of this thesis reports on the design, fabrication, and analysis of off-axis magnifier designs. The first design is catadioptric and consists of two elements. The lens utilizes a diffractive optical element and the mirror has a free-form surface described...
Show moreCompact and lightweight optical designs achieving acceptable image quality, field of view, eye clearance, eyebox size, operating across the visible spectrum, are the key to the success of next generation head-worn displays. The first part of this thesis reports on the design, fabrication, and analysis of off-axis magnifier designs. The first design is catadioptric and consists of two elements. The lens utilizes a diffractive optical element and the mirror has a free-form surface described with an x-y polynomial. A comparison of color correction between doublets and single layer diffractive optical elements in an eyepiece as a function of eye clearance is provided to justify the use of a diffractive optical element. The dual-element design has an 8 mm diameter eyebox, 15 mm eye clearance, 20 degree diagonal full field, and is designed to operate across the visible spectrum between 450-650 nm. 20% MTF at the Nyquist frequency with less than 3% distortion has been achieved in the dual-element head-worn display. An ideal solution for a head-worn display would be a single free-form surface mirror design. A single surface mirror does not have dispersion; therefore, color correction is not required. A single surface mirror can be made see-through by machining the appropriate surface shape on the opposite side to form a zero power shell. The second design consists of a single off-axis free-form mirror described with an x-y polynomial, which achieves a 3 mm diameter exit pupil, 15 mm eye relief, and a 24 degree diagonal full field of view. The second design achieves 10% MTF at the Nyquist frequency set by the pixel spacing of the VGA microdisplay with less than 3% distortion. Both designs have been fabricated using diamond turning techniques. Finally, this thesis addresses the question of "what is the optimal surface shape for a single mirror constrained in an off-axis magnifier configuration with multiple fields?" Typical optical surfaces implemented in raytrace codes today are functions mapping two dimensional vectors to real numbers. The majority of optical designs to-date have relied on conic sections and polynomials as the functions of choice. The choice of conic sections is justified since conic sections are stigmatic surfaces under certain imaging geometries. The choice of polynomials from the point of view of surface description can be challenged. A polynomial surface description may link a designer's understanding of the wavefront aberrations and the surface description. The limitations of using multivariate polynomials are described by a theorem due to Mairhuber and Curtis from approximation theory. This thesis proposes and applies radial basis functions to represent free-form optical surfaces as an alternative to multivariate polynomials. We compare the polynomial descriptions to radial basis functions using the MTF criteria. The benefits of using radial basis functions for surface description are summarized in the context of specific head-worn displays. The benefits include, for example, the performance increase measured by the MTF, or the ability to increase the field of view or pupil size. Even though Zernike polynomials are a complete and orthogonal set of basis over the unit circle and they can be orthogonalized for rectangular or hexagonal pupils using Gram-Schmidt, taking practical considerations into account, such as optimization time and the maximum number of variables available in current raytrace codes, for the specific case of the single off-axis magnifier with a 3 mm pupil, 15 mm eye relief, 24 degree diagonal full field of view, we found the Gaussian radial basis functions to yield a 20% gain in the average MTF at 17 field points compared to a Zernike (using 66 terms) and an x-y polynomial up to and including 10th order. The linear combination of radial basis function representation is not limited to circular apertures. Visualization tools such as field map plots provided by nodal aberration theory have been applied during the analysis of the off-axis systems discussed in this thesis. Full-field displays are used to establish node locations within the field of view for the dual-element head-worn display. The judicious separation of the nodes along the x-direction in the field of view results in well-behaved MTF plots. This is in contrast to an expectation of achieving better performance through restoring symmetry via collapsing the nodes to yield field-quadratic astigmatism.
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Date Issued: 2008
Identifier: CFE0002479, ucf:47674
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002479

Title: UP-CONVERSION IN RARE-EARTH DOPED MICRO-PARTICLES APPLIED TO NEW EMISSIVE 2D DISLAYS.
Creator: Milliez, Anne, Bass, Michael, University of Central Florida
Abstract / Description: Up-conversion (UC) in rare-earth co-doped fluorides to convert diode laser light in the near infrared to red, green and blue visible light is applied to make possible high performance emissive displays. The infrared-to-visible UC in the materials we study is a sequential form of non-linear two photon absorption in which a strong absorbing constituent absorbs two low energy photons and transfers this energy to another constituent which emits visible light. Some of the UC emitters' most...
Show moreUp-conversion (UC) in rare-earth co-doped fluorides to convert diode laser light in the near infrared to red, green and blue visible light is applied to make possible high performance emissive displays. The infrared-to-visible UC in the materials we study is a sequential form of non-linear two photon absorption in which a strong absorbing constituent absorbs two low energy photons and transfers this energy to another constituent which emits visible light. Some of the UC emitters' most appealing characteristics for displays are: a wide color gamut with very saturated colors, very high brightness operation without damage to the emitters, long lifetimes and efficiencies comparable to those of existing technologies. Other advantages include simplicity of fabrication, versatility of operating modes, and the potential for greatly reduced display weight and depth. Thanks to recent advances in material science and diode laser technology at the excitation wavelength, UC selected materials can be very efficient visible emitters. However, optimal UC efficiencies strongly depend on chosing proper operating conditions. In this thesis, we studied the conditions required for optimization. We demonstrated that high efficiency UC depends on high pump irradiance, low temperature and low scattering. With this understanding we can predict how to optimally use UC emitters in a wide range of applications. In particular, we showed how our very efficient UC emitters can be applied to make full color displays and very efficient white light sources.
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Date Issued: 2006
Identifier: CFE0001058, ucf:46828
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001058

Title: 2 micron fiber lasers: power scaling concepts and limitations.
Creator: Sincore, Alex, Richardson, Martin, Amezcua Correa, Rodrigo, Schulzgen, Axel, Shah, Lawrence, University of Central Florida
Abstract / Description: Thulium- and holmium-doped fiber lasers (TDF and HDF) emitting at 2 micron offer unique benefits and applications compared to common ytterbium-doped 1 micron lasers. This dissertation details the concepts, limitations, design, and performance of four 2 micron fiber laser systems. While these lasers were developed for various end-uses, they also provide further insight into two major power scaling limitations. The first limitation is optical nonlinearities: specifically stimulated Brillouin...
Show moreThulium- and holmium-doped fiber lasers (TDF and HDF) emitting at 2 micron offer unique benefits and applications compared to common ytterbium-doped 1 micron lasers. This dissertation details the concepts, limitations, design, and performance of four 2 micron fiber laser systems. While these lasers were developed for various end-uses, they also provide further insight into two major power scaling limitations. The first limitation is optical nonlinearities: specifically stimulated Brillouin scattering (SBS) and modulation instability (MI). The second limitation is thermal failure due to inefficient pump conversion. First, a 21.5 W single-frequency, single-mode laser with adjustable output from continuous-wave to nanosecond pulses is developed. Measuring the SBS threshold versus pulse duration enables the Brillouin gain coefficient and gain bandwidth to be determined at 2 micron. Second, a 23 W spectrally-broadband, nanosecond pulsed laser is constructed for materials processing applications. The temporally incoherent multi-kW peak power pulses can also efficiently produce MI and supercontinuum generation by adjusting the input spectral linewidth. Third, the measured performance of in-band pumped TDF and HDF lasers are compared with simulations. HDF displays low efficiencies, which is explained by including ion clustering in the simulations. The TDF operates with impressive (>)90% slope efficiencies. Based on this result, a system design for (>)1 kW average power TDF amplifier is described. The designed final amplifier will be in-band pumped to enable high efficiency and low thermal load. The amplifier efficiency, operating bandwidth, thermal load, and nonlinear limits are modeled and analyzed to provide a framework for execution. Overall, this dissertation provides further insight and understanding on the various processes that limit power scaling of 2 micron fiber lasers.
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Date Issued: 2018
Identifier: CFE0007374, ucf:52105
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007374

Title: Mode coupling in space-division multiplexed systems.
Creator: Liu, Huiyuan, Li, Guifang, Likamwa, Patrick, Amezcua Correa, Rodrigo, Chanda, Debashis, University of Central Florida
Abstract / Description: Even though fiber-optic communication systems have been engineered to nearly approach the Shannon capacity limit, they still cannot meet the exponentially-growing bandwidth demand of the Internet. Space-division multiplexing (SDM) has attracted considerable attention in recent years due to its potential to address this capacity crunch. In SDM, the transmission channels support more than one spatial mode, each of which can provide the same capacity as a single-mode fiber. To make SDM practical...
Show moreEven though fiber-optic communication systems have been engineered to nearly approach the Shannon capacity limit, they still cannot meet the exponentially-growing bandwidth demand of the Internet. Space-division multiplexing (SDM) has attracted considerable attention in recent years due to its potential to address this capacity crunch. In SDM, the transmission channels support more than one spatial mode, each of which can provide the same capacity as a single-mode fiber. To make SDM practical, crosstalk among modes must be effectively managed. This dissertation presents three techniques for crosstalk management for SDM. In some cases such as intra-datacenter interconnects, even though mode crosstalk cannot be completely avoided, crosstalk among mode groups can be suppressed in properly-designed few-mode fibers to support mode group-multiplexed transmission. However, in most cases, mode coupling is unavoidable. In free-space optical (FSO) communication, mode coupling due to turbulence manifests as wavefront distortions. Since there is almost no modal dispersion in FSO, we demonstrate the use of few-mode pre-amplified receivers to mitigate the effect of turbulence without using adaptive optics. In fiber-optic communication, multi-mode fibers or long-haul few-mode fibers not only suffer from mode crosstalk but also large modal dispersion, which can only be compensated electronically using multiple-input-multiple-output (MIMO) digital signal processing (DSP). In this case, we take the counterintuitive approach of introducing strong mode coupling to reduce modal group delay and DSP complexity.
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Date Issued: 2019
Identifier: CFE0007831, ucf:52806
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007831

Title: Analysis and Design of Non-Hermitian Optical Systems.
Creator: Kazemi Jahromi, Ali, Abouraddy, Ayman, Christodoulides, Demetrios, Likamwa, Patrick, Chini, Michael, University of Central Florida
Abstract / Description: From a very general perspective, optical devices can be viewed as constructions based on the spatial engineering of the optical index of refraction. Sculpting the real part of the refractive index produces the wide variety of known passive optical devices, such as waveguides, resonators, gratings, among a plethora of other possibilities for managing the transport of light. Less attention has been directed to engineering the imaginary part of the refractive index (-) that is responsible for...
Show moreFrom a very general perspective, optical devices can be viewed as constructions based on the spatial engineering of the optical index of refraction. Sculpting the real part of the refractive index produces the wide variety of known passive optical devices, such as waveguides, resonators, gratings, among a plethora of other possibilities for managing the transport of light. Less attention has been directed to engineering the imaginary part of the refractive index (-) that is responsible for optical gain and absorption (-) in conjunction with the real part of the refractive index. Optical gain is the building block of amplifiers and lasers, while optical absorption is exploited in photovoltaic devices, photodetectors, and as dopants in lasing media. Recently, the field of non-Hermitian photonics has emerged in which the new opportunities afforded by the spatial engineering of the optical gain and loss in an optical device are being exploited. Indeed, the judicious design of such active devices can result in counterintuitive physical effects, new optical functionalities that enable unexpected applications, and enhanced performance of existing devices.In this work, we have theoretically and experimentally demonstrated four different non-Hermitian arrangements exhibiting novel non-trivial features. First, we show that the direction of energy flow can be controlled inside an active cavity by tuning the optical gain. Reversing the direction of the energy flow within the cavity (-) such that Poynting's vector points backwards towards the source (-) takes place when the cavity gain exceeds a certain threshold value, which we have named 'Poynting's threshold'. To realize this effect, we have employed a fiber-based arrangement that allows for unambiguous determining of the direction of the energy flow within the cavity. Second, we have studied the implication of Poynting's threshold with respect to spectral reflection from an active cavity. Surprisingly, the reflection at Poynting's threshold becomes spectrally flat and is guaranteed to attain unity reflectivity while maintaining non-zero transmission. In other words, at Poynting's threshold, the cavity becomes a 'transparent perfect mirror'. We have realized this effect in an on-chip active waveguide device and in an optical-fiber-based system. Third, we have examined a parity-time (PT) symmetric fiber-based cavity consisting of two coupled sub-cavities, one of which contains gain and the other loss. In contrast to all previous on-chip PT-symmetric micro-devices, the exotic features of such a system may be expected to vanish when the length of the cavity is extremely large (exceeding 1 km in our experiments) due to the strong fluctuations in the optical phase. Nevertheless, we have found that some of the central features of such a system survive; e.g., loss-induced enhancement of lasing power is still observable. Finally, we have demonstrated (-) for the first time (-) the interferometric perfect absorption of light in a weakly absorbing (erbium-doped) fiber system. Additionally, we verified that this coherent effect is the most efficient configuration with respect to utilizing the absorbing species in the medium.
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Date Issued: 2018
Identifier: CFE0007206, ucf:52271
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007206

Title: DEVELOPMENT OF OPTICAL COHERENCE TOMOGRAPHY FOR TISSUE DIAGNOSTICS.
Creator: Meemon, Panomsak, Rolland, Jannick, University of Central Florida
Abstract / Description: Microvasculature can be found in almost every part of the human body, including the internal organs. Importantly, abnormal changes in microvasculature are usually related to pathological development of the tissue cells. Monitoring of changes in blood flow properties in microvasculature, therefore, provides useful diagnostic information about pathological conditions in biological tissues as exemplified in glaucoma, diabetes, age related macular degeneration, port wine stains, burn-depth, and...
Show moreMicrovasculature can be found in almost every part of the human body, including the internal organs. Importantly, abnormal changes in microvasculature are usually related to pathological development of the tissue cells. Monitoring of changes in blood flow properties in microvasculature, therefore, provides useful diagnostic information about pathological conditions in biological tissues as exemplified in glaucoma, diabetes, age related macular degeneration, port wine stains, burn-depth, and potentially skin cancer. However, the capillary network is typically only one cell in wall thickness with 5 to 10 microns in diameter and located in the dermis region of skin. Therefore, a non-invasive flow imaging technique that is capable of depth sectioning at high resolution and high speed is demanded. Optical coherence tomography (OCT), particularly after its advancement in frequency domain OCT (FD-OCT), is a promising tool for non-invasive high speed, high resolution, and high sensitivity depth-resolved imaging of biological tissues. Over the last ten years, numerous efforts have been paid to develop OCT-based flow imaging techniques. An important effort is the development of phase-resolved Doppler OCT (PR-DOCT). Phase-resolved Doppler imaging using FD-OCT is particularly of interest because of the direct access to the phase information of the depth profile signal. Furthermore, the high speed capability of FD-OCT is promising for real time flow monitoring as well as 3D flow segmentation applications. However, several challenges need to be addressed; 1) Flow in biological samples exhibits a wide dynamic range of flow velocity caused by, for example, the variation in the flow angles, flow diameters, and functionalities. However, the improvement in imaging speed of FD-OCT comes at the expense of a reduction in sensitivity to slow flow information and hence a reduction in detectable velocity range; 2) A structural ambiguity so-called 'mirror image' in FD-OCT prohibits the use of maximum sensitivity and imaging depth range; 3) The requirement of high lateral resolution to resolve capillary vessels requires the use of an imaging optics with high numerical aperture (NA) that leads to a reduction in depth of focus (DOF) and hence the imaging depth range (i.e. less than 100 microns) unless dynamic focusing is performed. Nevertheless, intrinsic to the mechanism of FD-OCT, dynamic focusing is not possible. In this dissertation, the implementation of PR-DOCT in a high speed swept-source based FD-OCT is investigated and optimized. An acquisition scheme as well as a processing algorithm that effectively extends the detectable velocity dynamic range of the PR-DOCT is presented. The proposed technique increased the overall detectable velocity dynamic range of PR-DOCT by about five times of that achieved by the conventional method. Furthermore, a novel technique of mirror image removal called Ã‚Â'Dual-Detection FD-OCTÃ‚Â' (DD-FD-OCT) is presented. One of the advantages of DD-FD-OCT to Doppler imaging is that the full-range signal is achieved without manipulation of the phase relation between consecutive axial lines. Hence the full-range DD-FD-OCT is fully applicable to phase-resolved Doppler detection without a reduction in detectable velocity dynamic range as normally encountered in other full-range techniques. In addition, PR- DOCT can utilize the maximum signal-to-noise ratio provided by the full-range capability. This capability is particularly useful for imaging of blood flow that locates deep below the sample surface, such as blood flow at deep posterior human eye and blood vessels network in the dermis region of human skin. Beside high speed and functional imaging capability, another key parameter that will open path for optical diagnostics using OCT technology is high resolution imaging (i.e. in a regime of a few microns or sub-micron). Even though the lateral resolution of OCT can be independently improved by opening the NA of the imaging optics, the high lateral resolution is maintained only over a short range as limited by the depth of focus that varies inversely and quadratically with NA. Recently developed by our group, Ã‚Â'Gabor-Domain Optical Coherence MicroscopyÃ‚Â' (GD-OCM) is a novel imaging technique capable for invariant resolution of about 2-3 microns over a 2 mm cubic field-of-view. This dissertation details the imaging protocol as well as the automatic data fusion method of GD-OCM developed to render an in-focus high-resolution image throughout the imaging depth of the sample in real time. For the application of absolute flow measurement as an example, the precise information about flow angle is required. GD-OCM provides more precise interpretation of the tissue structures over a large field-of-view, which is necessary for accurate mapping of the flow structure and hence is promising for diagnostic applications particularly when combined with Doppler imaging. Potentially, the ability to perform high resolution OCT imaging inside the human body is useful for many diagnostic applications, such as providing an accurate map for biopsy, guiding surgical and other treatments, monitoring the functional state and/or the post-operative recovery process of internal organs, plaque detection in arteries, and early detection of cancers in the gastrointestinal tract. Endoscopic OCT utilizes a special miniature probe in the sample arm to access tubular organs inside the human body, such as the cardiovascular system, the lung, the gastrointestinal tract, the urinary tract, and the breast duct. We present an optical design of a dynamic focus endoscopic probe that is capable of about 4 to 6 microns lateral resolution over a large working distance (i.e. up to 5 mm from the distal end of the probe). The dynamic focus capability allows integration of the endoscopic probe to GD-OCM imaging to achieve high resolution endoscopic tomograms. We envision the future of this developing technology as a solution to high resolution, minimally invasive, depth-resolved imaging of not only structure but also the microvasculature of in vivo biological tissues that will be useful for many clinical applications, such as dermatology, ophthalmology, endoscopy, and cardiology. The technology is also useful for animal study applications, such as the monitoring of an embryoÃ‚Â's heart for the development of animal models and monitoring of changes in blood circulation in response to external stimulus in small animal brains.
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Date Issued: 2010
Identifier: CFE0003442, ucf:48392
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003442

Title: FREEFORM REFLECTOR DESIGN WITH EXTENDED SOURCES.
Creator: Fournier, Florian, Rolland, Jannick, University of Central Florida
Abstract / Description: Reflector design stemmed from the need to shape the light emitted by candles or lamps. Over 2,000 years ago people realized that a mirror shaped as a parabola can concentrate light, and thus significantly boosts its intensity, to the point where objects can be set afire. Nowadays many applications require an accurate control of light, such as automotive headlights, streetlights, projection displays, and medical illuminators. In all cases light emitted from a light source can be shaped into a...
Show moreReflector design stemmed from the need to shape the light emitted by candles or lamps. Over 2,000 years ago people realized that a mirror shaped as a parabola can concentrate light, and thus significantly boosts its intensity, to the point where objects can be set afire. Nowadays many applications require an accurate control of light, such as automotive headlights, streetlights, projection displays, and medical illuminators. In all cases light emitted from a light source can be shaped into a desired target distribution with a reflective surface. Design methods for systems with rotational and translational symmetry were devised in the 1930s. However, the freeform reflector shapes required to illuminate targets with no such symmetries proved to be much more challenging to design. Even when the source is assumed to be a point, the reflector shape is governed by a set of second-order partial non-linear differential equations that cannot be solved with standard numerical integration techniques. An iterative approach to solve the problem for a discrete target, known as the method of supporting ellipsoids, was recently proposed by Oliker. In this research we report several efficient implementations of the method of supporting ellipsoids, based on the point source approximation, and we propose new reflector design techniques that take into account the extent of the source. More specifically, this work has led to three major achievements. First, a thorough analysis of the method of supporting ellipsoids was performed that resulted in two alternative implementations of the algorithm, which enable a fast generation of freeform reflector shapes within the point source approximation. We tailored the algorithm in order to provide control over the parameters of interest to the designers, such as the reflector scale and geometry. Second, the shape generation algorithm was used to analyze how source flux can be mapped onto the target. We derived the condition under which a given source-target mapping can be achieved with a smooth continuous surface, referred as the integrability condition. We proposed a method to derive mappings that satisfy the integrability condition. We then use these mappings to quickly generate reflector shapes that create continuous target distributions as opposed to reflectors generated with the method of supporting ellipsoids that create discrete sets of points on the target. We also show how mappings that do not satisfy the integrability condition can be achieved by introducing step discontinuities in the reflector surface. Third, we investigated two methods to design reflectors with extended sources. The first method uses a compensation approach where the prescribed target distribution is adjusted iteratively. This method is effective for compact sources and systems with rotational or translational symmetry. The second method tiles the source images created by a reflector designed with the method of supporting ellipsoids and then blends the source images together using scattering in order to obtain a continuous target distribution. This latter method is effective for freeform reflectors and target distributions with no sharp variations. Finally, several case studies illustrate how these methods can be successfully applied to design reflectors for general illumination applications such as street lighting or luminaires. We show that the proposed design methods can ease the design of freeform reflectors and provide efficient, cost-effective solutions that avoid unnecessary energy consumption and light pollution.
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Date Issued: 2010
Identifier: CFE0003311, ucf:48508
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003311

Title: Dynamic feedback pulse shaping for high power chirped pulse amplification system.
Creator: Nguyen, Dat, Delfyett, Peter, Rahman, Talat, Richardson, Martin, Schulzgen, Axel, Li, Guifang, University of Central Florida
Abstract / Description: The topic of this proposal is the development of high peak power laser sources with a focus on linearly chirped pulse laser sources. In the past decade chirped optical pulses have found a plethora of applications such as photonic analog-to-digital conversion, optical coherence tomography, laser ranging, etc. This dissertation analyzes the aforementioned applications of linearly chirped pulses and their technical requirements, as well as the performance of previously demonstrated parabolic...
Show moreThe topic of this proposal is the development of high peak power laser sources with a focus on linearly chirped pulse laser sources. In the past decade chirped optical pulses have found a plethora of applications such as photonic analog-to-digital conversion, optical coherence tomography, laser ranging, etc. This dissertation analyzes the aforementioned applications of linearly chirped pulses and their technical requirements, as well as the performance of previously demonstrated parabolic pulse shaping approaches. The experimental research addresses the topic of parabolic pulse generation in two distinct ways. First, pulse shaping technique involving a time domain approach is presented, that results in stretched pulses with parabolic profiles with temporal duration of 15 ns. After pulse is shaped into a parabolic intensity profile, the pulse is compressed with DCF fiber spool by 100 times to 80 ps duration at FWHM. A different approach of pulse shaping in frequency domain is performed, in which a spectral processor based on Liquid Crystal on Silicon technology is used. The pulse is stretched to 1.5 ns before intensity mask is applied, resulting in a parabolic intensity profile. Due to frequency to time mapping, its temporal profile is also parabolic. After pulse shaping, the pulse is compressed with a bulk compressor, and subsequently analyzed with a Frequency Resolved Optical Gating (FROG). The spectral content of the compressed pulse is feedback to the spectral processor and used to adjust the spectral phase mask applied on the pulse. The resultant pulse after pulse shaping with feedback mechanism is a Fourier transform, sub-picosecond ultrashort pulse with 5 times increase in peak power.The appendices in this dissertation provide additional material used for the realization of the main research focus of the dissertation. Specification and characterization of major components of equipment and devices used in the experiment are present. The description of Matlab algorithms that was used to calculate required signals for pulse shaping are shown. A brief description of the Labview code used to control the spectral processor will also be illustrated.
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Date Issued: 2013
Identifier: CFE0004899, ucf:49642
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004899

Title: Particle Manipulation Via Optical Forces and Engineering Soft-Matter Systems With Tunable Nonlinearities.
Creator: Fardad, Shima, Christodoulides, Demetrios, Hagan, David, Amezcua Correa, Rodrigo, Likamwa, Patrick, Chen, Zhigang, University of Central Florida
Abstract / Description: One of the most intriguing properties of light-matter interaction is the ability of an electromagnetic field to exert mechanical forces on polarizable objects. This phenomenon is a direct consequence of the fact that light carries momentum, which in turn can be transferred to matter. Mediated by scattering, this interaction usually manifests itself as a (")pushing force(") in the direction of beam propagation. However, it is possible to judiciously engineer these optical forces, either by...
Show moreOne of the most intriguing properties of light-matter interaction is the ability of an electromagnetic field to exert mechanical forces on polarizable objects. This phenomenon is a direct consequence of the fact that light carries momentum, which in turn can be transferred to matter. Mediated by scattering, this interaction usually manifests itself as a (")pushing force(") in the direction of beam propagation. However, it is possible to judiciously engineer these optical forces, either by tailoring particle polarizability, and/or by structuring the incident light field. As a simple example, a tightly focused laser beam demonstrates strong gradient forces, which may attract and even trap particles with positive polarizability in the focal volume. The opposite occurs in the regime of negative polarizability, where particles are expelled from the regions of highest intensity. Based on this fundamental principle, one can actively shape the beam using spatial light modulators to manipulate individual objects as well as ensembles of particles suspended in a liquid. In the latter case, a modulation of the local particle concentration is associated with changes of the effective refractive index. The result is an artificial nonlinear medium, whose Kerr-type response can be readily tuned by the parameters of its constituent particles.In the course of this work, we introduce a new class of synthetic colloidal suspensions exhibiting negative polarizabilities, and observe for the first time robust propagation and enhanced transmission of self-trapped light over long distances. Such light penetration in strongly scattering environments is enabled by the interplay between optical forces and self-activated transparency effects. We explore various approaches to the design of negative-polarizability arrangements, including purely dielectric as well as metallic and hybrid nanoparticles. In particular, we find that plasmonic resonances allow for extremely high and spectrally tunable polarizabilities, leading to unique nonlinear light-matter interactions. Here, for the first time we were able to observe plasmonic resonant solitons over more than 25 diffraction lengths, in colloidal nanosuspensions.
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Date Issued: 2014
Identifier: CFE0005610, ucf:50239
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005610

Title: Injection-Locked Vertical Cavity Surface Emitting Lasers (VCSELs) for Optical Arbitrary Waveform Generation.
Creator: Bhooplapur, Sharad, Delfyett, Peter, Li, Guifang, Christodoulides, Demetrios, Malocha, Donald, University of Central Florida
Abstract / Description: Complex optical pulse shapes are typically generated from ultrashort laser pulses by manipulating the optical spectrum of the input pulses. This generates complex but periodic time-domain waveforms. Optical Arbitrary Waveform Generation (OAWG) builds on the techniques of ultrashort pulse?shaping, with the goal of making non?periodic, truly arbitrary optical waveforms. Some applications of OAWG are coherently controlling chemical reactions on a femtosecond time scale, improving the performance...
Show moreComplex optical pulse shapes are typically generated from ultrashort laser pulses by manipulating the optical spectrum of the input pulses. This generates complex but periodic time-domain waveforms. Optical Arbitrary Waveform Generation (OAWG) builds on the techniques of ultrashort pulse?shaping, with the goal of making non?periodic, truly arbitrary optical waveforms. Some applications of OAWG are coherently controlling chemical reactions on a femtosecond time scale, improving the performance of LADAR systems, high?capacity optical telecommunications and ultra wideband signals processing.In this work, an array of Vertical Cavity Surface Emitting Lasers (VCSELs) are used as modulators, by injection-locking each VCSEL to an individual combline from an optical frequency comb source. Injection-locking ensures that the VCSELs' emission is phase coherent with the input combline, and modulating its current modulates mainly the output optical phase. The multi-GHz modulation bandwidth of VCSELs updates the output optical pulse shape on a pulse-to-pulse time scale, which is an important step towards true OAWG. In comparison, it is about a million times faster than the liquid-crystal modulator arrays typically used for pulse shaping! Novel components and subsystems of Optical Arbitrary Waveform Generation (OAWG) are developed and demonstrated in this work. They include:1.Modulators An array of VCSELs is packaged and characterized for use as a modulator for rapid?update pulse?shaping at GHz rates. The amplitude and phase modulation characteristics of an injection?locked VCSEL are simultaneously measured at GHz modulation rates.2.Optical Frequency Comb SourcesAn actively mode?locked semiconductor laser was assembled, with a 12.5 GHz repetition rate, ~ 200 individually resolvable comblines directly out of the laser, and high frequency stability. In addition, optical frequency comb sources are generated by modulation of a single frequency laser.3.High-resolution optical spectral demultiplexersThe demultiplexers are implemented using bulk optics, and are used to spatially resolve individual optical comblines onto the modulator array. 4.Optical waveform measurement techniques Several techniques are used to measure generated waveforms, especially for spectral phase measurements, including multi-heterodyne phase retrieval. In addition, an architecture for discriminating between ultrashort encoded optical pulses with record high sensitivity is demonstrated.
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Date Issued: 2014
Identifier: CFE0005466, ucf:50402
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005466

Title: Reduced Susceptibility of Deformation due to Vibrational and Gravitational Effects on a Focus Variable Adaptive Lens.
Creator: Relina, Victoriya, Wu, Shintson, Likamwa, Patrick, Delfyett, Peter, University of Central Florida
Abstract / Description: Orthodox optical devices, such as lenses, mirrors, and prisms, are composed of solid-state materials, which although well studied and implemented ubiquitously are severely limited in their adaptable properties. An arguably new field of adaptive optics has emerged to further expand photonic manipulation competences of optical components. Fluid-based adaptive optical components were introduced as early as 1968; such components have the ability to change the shape of their interface surface,...
Show moreOrthodox optical devices, such as lenses, mirrors, and prisms, are composed of solid-state materials, which although well studied and implemented ubiquitously are severely limited in their adaptable properties. An arguably new field of adaptive optics has emerged to further expand photonic manipulation competences of optical components. Fluid-based adaptive optical components were introduced as early as 1968; such components have the ability to change the shape of their interface surface, thus allowing for a variable curvature profile. The method of manipulation varies greatly, as does the range of surface deformations. A solid-state optical component is affected by system vibration variation only (difference in vibration from one component to the other due to damping effect). By comparison, two large limiting factors of a fluid-based adaptive optical component are the effect of local vibrations on the surface of the device and gravitational effect (when the optical axis of a lens is positioned parallel to gravitational pull). Such a gravitational effect has been mitigated by the invention of the mechanical electrowetting lens, which uses density matching of two liquids that make up an adaptive lens. However, this configuration creates an extra limiting factor of density matching two optically clear fluids with a desirable transmission spectrum. This method can also become bulky when a large aperture is needed. In this thesis, two adaptive lens systems are explored. Principles of operation, performance, limitations, as well as future improvements are studied and theorized. The first lens uses an optically clear elastomer as the substrate of an adaptive lens and a primitive mechanical manipulation to turn a plano(-)plano lens into a plano(-)convex lens. The second lens is composed of an optically clear gel rather than a fluid. Both methods exhibit excellent optical properties regardless of the orientation about the gravitational pull and significantly limit local vibration affects simply by the physical nature of the chosen materials.
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Date Issued: 2013
Identifier: CFE0004739, ucf:49841
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004739

Title: DESIGN AND ASSESSMENT OF COMPACT OPTICAL SYSTEMS TOWARDS SPECIAL EFFECTS IMAGING.
Creator: Chaoulov, Vesselin, Rolland, Jannick, University of Central Florida
Abstract / Description: A main challenge in the field of special effects is to create special effects in real time in a way that the user can preview the effect before taking the actual picture or movie sequence. There are many techniques currently used to create computer-simulated special effects, however current techniques in computer graphics do not provide the option for the creation of real-time texture synthesis. Thus, while computer graphics is a powerful tool in the field of special effects, it is neither...
Show moreA main challenge in the field of special effects is to create special effects in real time in a way that the user can preview the effect before taking the actual picture or movie sequence. There are many techniques currently used to create computer-simulated special effects, however current techniques in computer graphics do not provide the option for the creation of real-time texture synthesis. Thus, while computer graphics is a powerful tool in the field of special effects, it is neither portable nor does it provide work in real-time capabilities. Real-time special effects may, however, be created optically. Such approach will provide not only real-time image processing at the speed of light but also a preview option allowing the user or the artist to preview the effect on various parts of the object in order to optimize the outcome. The work presented in this dissertation was inspired by the idea of optically created special effects, such as painterly effects, encoded in images captured by photographic or motion picture cameras. As part of the presented work, compact relay optics was assessed, developed, and a working prototype was built. It was concluded that even though compact relay optics can be achieved, further push for compactness and cost-effectiveness was impossible in the paradigm of bulk macro-optics systems. Thus, a paradigm for imaging with multi-aperture micro-optics was proposed and demonstrated for the first time, which constitutes one of the key contributions of this work. This new paradigm was further extended to the most general case of magnifying multi-aperture micro-optical systems. Such paradigm allows an extreme reduction in size of the imaging optics by a factor of about 10 and a reduction in weight by a factor of about 500. Furthermore, an experimental quantification of the feasibility of optically created special effects was completed, and consequently raytracing software was developed, which was later commercialized by SmARTLens(TM). While the art forms created via raytracing were powerful, they did not predict all effects acquired experimentally. Thus, finally, as key contribution of this work, the principles of scalar diffraction theory were applied to optical imaging of extended objects under quasi-monochromatic incoherent illumination in order to provide a path to more accurately model the proposed optical imaging process for special effects obtained in the hardware. The existing theoretical framework was generalized to non-paraxial in- and out-of-focus imaging and results were obtained to verify the generalized framework. In the generalized non-paraxial framework, even the most complex linear systems, without any assumptions for shift invariance, can be modeled and analyzed.
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Date Issued: 2005
Identifier: CFE0000513, ucf:46447
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000513

Title: Harnessing Spatial Intensity Fluctuations for Optical Imaging and Sensing.
Creator: Akhlaghi Bouzan, Milad, Dogariu, Aristide, Saleh, Bahaa, Pang, Sean, Atia, George, University of Central Florida
Abstract / Description: Properties of light such as amplitude and phase, temporal and spatial coherence, polarization, etc. are abundantly used for sensing and imaging. Regardless of the passive or active nature of the sensing method, optical intensity fluctuations are always present! While these fluctuations are usually regarded as noise, there are situations where one can harness the intensity fluctuations to enhance certain attributes of the sensing procedure. In this thesis, we developed different sensing...
Show moreProperties of light such as amplitude and phase, temporal and spatial coherence, polarization, etc. are abundantly used for sensing and imaging. Regardless of the passive or active nature of the sensing method, optical intensity fluctuations are always present! While these fluctuations are usually regarded as noise, there are situations where one can harness the intensity fluctuations to enhance certain attributes of the sensing procedure. In this thesis, we developed different sensing methodologies that use statistical properties of optical fluctuations for gauging specific information. We examine this concept in the context of three different aspects of computational optical imaging and sensing. First, we study imposing specific statistical properties to the probing field to image or characterize certain properties of an object through a statistical analysis of the spatially integrated scattered intensity. This offers unique capabilities for imaging and sensing techniques operating in highly perturbed environments and low-light conditions. Next, we examine optical sensing in the presence of strong perturbations that preclude any controllable field modification. We demonstrate that inherent properties of diffused coherent fields and fluctuations of integrated intensity can be used to track objects hidden behind obscurants. Finally, we address situations where, due to coherent noise, image accuracy is severely degraded by intensity fluctuations. By taking advantage of the spatial coherence properties of optical fields, we show that this limitation can be effectively mitigated and that a significant improvement in the signal-to-noise ratio can be achieved even in one single-shot measurement. The findings included in this dissertation illustrate different circumstances where optical fluctuations can affect the efficacy of computational optical imaging and sensing. A broad range of applications, including biomedical imaging and remote sensing, could benefit from the new approaches to suppress, enhance, and exploit optical fluctuations, which are described in this dissertation.
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Date Issued: 2017
Identifier: CFE0007274, ucf:52200
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007274

Title: DEVELOPMENT OF A COMPACT BROADBAND OPTICAL PARAMETRIC OSCILLATOR FOR ULTRA-SENSITIVE MOLECULAR DETECTION.
Creator: Crystal, Sean O, Vodopyanov, Konstantin L., University of Central Florida
Abstract / Description: Every gas molecule has a unique absorption spectrum that can be captured using optical spectroscopy to identify an unknown sample's composition. Frequency combs systems can provide an extremely broad mid-infrared spectrum that is very useful for molecular detection. A degenerate optical parametric oscillator (OPO) was built to generate the down-converted and shifted frequency comb spectrum. This system utilizes an ultra-short pulse 1.56�m pump laser and a never before used orientation...
Show moreEvery gas molecule has a unique absorption spectrum that can be captured using optical spectroscopy to identify an unknown sample's composition. Frequency combs systems can provide an extremely broad mid-infrared spectrum that is very useful for molecular detection. A degenerate optical parametric oscillator (OPO) was built to generate the down-converted and shifted frequency comb spectrum. This system utilizes an ultra-short pulse 1.56�m pump laser and a never before used orientation patterned gallium-phosphide crystal. Periodically polled lithium niobate (PPLN), Gallium Arsenide (GaAs) and Gallium Phosphide are all crystals used to accomplish this task. GaP, in comparison to PPLN, has (i) a larger nonlinear coefficient, (ii) much deeper infrared transparency, and (iii) smaller group dispersion � to allow for achieving broad spectral coverage. GaP also has a larger band gap than GaAs; therefore it can still be pumped with a standard telecom C-band laser. An octave-wide spanning frequency comb system was achieved and the characterization of the system is presented. This system is specifically designed to be compact and portable for initial experimental testing in the applications of medical breath analysis and combustion gas investigation.
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Date Issued: 2017
Identifier: CFH2000274, ucf:45837
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH2000274

optics (14)	+ -
nonlinear optics (13)	+ -
Optics (12)	+ -
Nonlinear Optics (8)	+ -
optical (6)	+ -

Laser (5)	+ -
integrated photonics (5)	+ -
laser (5)	+ -
optical flow (5)	+ -
semiconductor lasers (5)	+ -
Nonlinear optics (4)	+ -
mode-locked lasers (4)	+ -
two-photon absorption (4)	+ -
Filamentation (3)	+ -
Integrated photonics (3)	+ -
Mid-infrared (3)	+ -
Optical Networks (3)	+ -
Optical Sensing (3)	+ -
Optical Sensors (3)	+ -
Optical data processing (3)	+ -
Optical properties (3)	+ -
Photonics (3)	+ -
Plasma (3)	+ -
Spectroscopy (3)	+ -
Two-Photon Absorption (3)	+ -
beam shaping (3)	+ -
computer vision (3)	+ -
frequency combs (3)	+ -
integrated optics (3)	+ -
nanophotonics (3)	+ -

ETD Collection (201)	+ -
Honors Collection (2)	+ -

University of Central Florida (200)	+ -
Christodoulides, Demetrios (24)	+ -
Delfyett, Peter (23)	+ -
Likamwa, Patrick (22)	+ -
Li, Guifang (17)	+ -

Richardson, Martin (17)	+ -
Schulzgen, Axel (14)	+ -
Dogariu, Aristide (13)	+ -
Hagan, David (12)	+ -
Peale, Robert (11)	+ -
Schoenfeld, Winston (11)	+ -
Vanstryland, Eric (10)	+ -
Abouraddy, Ayman (9)	+ -
Fathpour, Sasan (9)	+ -
Rolland, Jannick (9)	+ -
Wu, Shintson (8)	+ -
Amezcua Correa, Rodrigo (6)	+ -
Kik, Pieter (6)	+ -
Leuenberger, Michael (6)	+ -
Rahman, Talat (6)	+ -
Zeldovich, Boris (6)	+ -
Bassiouni, Mostafa (5)	+ -
Hernandez, Florencio (5)	+ -
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Phillips, Ronald (5)	+ -
Riza, Nabeel (5)	+ -
Sundaram, Kalpathy (5)	+ -
Zou, Shengli (5)	+ -
Abdolvand, Reza (4)	+ -
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