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Title: Laser Filamentation - Beyond Self-focusing and Plasma Defocusing.
Creator: Lim, Khan, Richardson, Martin, Chang, Zenghu, Christodoulides, Demetrios, Zhang, Xi-Cheng, University of Central Florida
Abstract / Description: Laser filamentation is a highly complex and dynamic nonlinear process that is sensitive to many physical parameters. The basic properties that define a filament consist of (i) a narrow, high intensity core that persists for distances much greater than the Rayleigh distance, (ii) a low density plasma channel existing within the filament core, and (iii) a supercontinuum generated over the course of filamentation. However, there remain many questions pertaining to how these basic properties are...
Show moreLaser filamentation is a highly complex and dynamic nonlinear process that is sensitive to many physical parameters. The basic properties that define a filament consist of (i) a narrow, high intensity core that persists for distances much greater than the Rayleigh distance, (ii) a low density plasma channel existing within the filament core, and (iii) a supercontinuum generated over the course of filamentation. However, there remain many questions pertaining to how these basic properties are affected by changes in the conditions in which the filaments are formed; that is the premise of the work presented in this dissertation.To examine the effects of anomalous dispersion and of different multi-photon ionization regimes, filaments were formed in solids with different laser wavelengths. The results provided a better understanding of supercontinuum generation in the anomalous dispersion regime, and of how multi-photon ionization can affect the formation of filaments.Three different experiments were carried out on filamentation in air. The first was an investigation into the effects of geometrical focusing. A simplified theoretical model was derived to determine the transition of filamentation in the linear-focusing and nonlinear- focusing regimes. The second examined the effects of polarization on supercontinuum generation, where a polarization-dependent anomalous spectral broadening phenomenon due to molecular effects was identified. The third involved the characterization of filaments in the ultraviolet. The combination of physical mechanisms responsible for filamentation in the ultraviolet was found to be different from that in the near infrared.
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Date Issued: 2014
Identifier: CFE0005520, ucf:50317
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005520

Title: Conservation Laws and Electromagnetic Interactions.
Creator: Kajorndejnukul, Veerachart, Dogariu, Aristide, Abouraddy, Ayman, Kik, Pieter, Rahman, Talat, University of Central Florida
Abstract / Description: Aside from energy, light carries linear and angular momenta that can be transferred to matter. The interaction between light and matter is governed by conservation laws that can manifest themselves as mechanical effects acting on both matter and light waves. This interaction permits remote, precise, and noninvasive manipulation and sensing at microscopic levels. In this dissertation, we demonstrated for the first time a complete set of opto-mechanical effects that are based on nonconservative...
Show moreAside from energy, light carries linear and angular momenta that can be transferred to matter. The interaction between light and matter is governed by conservation laws that can manifest themselves as mechanical effects acting on both matter and light waves. This interaction permits remote, precise, and noninvasive manipulation and sensing at microscopic levels. In this dissertation, we demonstrated for the first time a complete set of opto-mechanical effects that are based on nonconservative forces and act at the interface between dielectric media. Without structuring the light field, forward action is provided by the conventional radiation pressure while a backward movement can be achieved through the natural enhancement of linear momentum. If the symmetry of scattered field is broken, a side motion can also be induced due to the transformation between spin and orbital angular momenta. In experiments, these opto-mechanical effects can be significantly amplified by the long-range hydrodynamic interactions that provide an efficient recycling of energy. These unusual opto-mechanical effects open new possibilities for efficient manipulation of colloidal microparticles without having to rely on intricate structuring or shaping of light beams. Optically-controlled transport of matter is sought after in diverse applications in biology, colloidal physics, chemistry, condensed matter and others.Another consequence of light-matter interaction is the modification of the optical field itself, which can manifest, for instance, as detectable shifts of the centroids of optical beams during reflection and refraction. The spin-Hall effect of light (SHEL) is one type of such beam shifts that is due to the spin-orbit transformation governed by the conservation of angular momentum. We have shown that this effect can be amplified by the structural anisotropy of random nanocomposite materials.
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Date Issued: 2015
Identifier: CFE0005961, ucf:50818
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005961

Title: Entangled Photon Pairs in Disordered Photonic Lattices.
Creator: Martin, Lane, Saleh, Bahaa, Abouraddy, Ayman, Christodoulides, Demetrios, Leuenberger, Michael, University of Central Florida
Abstract / Description: Photonic lattices consisting of arrays of evanescently coupled waveguides fabricated with precisely controlled parameters have enabled the study of discrete optical phenomena, both classical and quantum, and the simulation of other physical phenomena governed by the same dynamics. In this dissertation, I have experimentally demonstrated transverse Anderson localization of classical light in arrays with off-diagonal coupling disorder and investigated theoretically and experimentally the...
Show morePhotonic lattices consisting of arrays of evanescently coupled waveguides fabricated with precisely controlled parameters have enabled the study of discrete optical phenomena, both classical and quantum, and the simulation of other physical phenomena governed by the same dynamics. In this dissertation, I have experimentally demonstrated transverse Anderson localization of classical light in arrays with off-diagonal coupling disorder and investigated theoretically and experimentally the propagation of entangled photon pairs through such disordered systems. I discovered a new phenomenon, Anderson co-localization, in which a spatially entangled photon pair in a correlated transversally extended state localizes in the correlation space, though neither photon localizes on its own. When the photons of a pair are in an anti-correlated state, they maintain their anti-correlation upon transmission through the disordered lattice, exhibiting Anderson anti-localization. These states were generated by use of parametric down conversion in a nonlinear crystal. The transition between the correlated and anti-correlated states was also explored by using a lens system in a configuration intermediate between imaging and Fourier transforming. In the course of this research, I discovered a curious aspect of light transmission through such disordered discrete lattices. An excitation wave of a single spatial frequency (transverse momentum) is transmitted through the system and is accompanied by another wave with the same spatial frequency but opposite sign, indicating some form of internal reflection facilitated by the disordered structure.
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Date Issued: 2014
Identifier: CFE0005527, ucf:50312
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005527

Title: MONOLITHIC INTEGRATION OF DUAL OPTICAL ELEMENTS ON HIGH POWER SEMICONDUCTOR LASERS.
Creator: vaissie, laurent, Johnson, Eric, University of Central Florida
Abstract / Description: This dissertation investigates the monolithic integration of dual optical elements on high power semiconductor lasers for emission around 980nm wavelength. In the proposed configuration, light is coupled out of the AlGaAs/GaAs waveguide by a low reflectivity grating coupler towards the substrate where a second monolithic optical element is integrated to improve the device performance or functionality. A fabrication process based on electron beam lithography and plasma etching was developed to...
Show moreThis dissertation investigates the monolithic integration of dual optical elements on high power semiconductor lasers for emission around 980nm wavelength. In the proposed configuration, light is coupled out of the AlGaAs/GaAs waveguide by a low reflectivity grating coupler towards the substrate where a second monolithic optical element is integrated to improve the device performance or functionality. A fabrication process based on electron beam lithography and plasma etching was developed to control the grating coupler duty cycle and shape. The near-field intensity profile outcoupled by the grating is modeled using a combination of finite-difference time domain (FDTD) analysis of the nonuniform grating and a self-consistent model of the broad area active region. Improvement of the near-field intensity profile in good agreement with the FDTD model is demonstrated by varying the duty cycle from 20% to 55% and including the aspect ratio dependent etching (ARDE) for sub-micron features. The grating diffraction efficiency is estimated to be higher than 95% using a detailed analysis of the losses mechanisms of the device. The grating reflectivity is estimated to be as low as 2.10-4. The low reflectivity of the light extraction process is shown to increase the device efficiency and efficiently suppress lasing oscillations if both cleaved facets are replaced by grating couplers to produce 1.5W QCW with 11nm bandwidth into a single spot a few mm above the device. Peak power in excess of 30W without visible COMD is achieved in this case. Having optimized, the light extraction process, we demonstrate the integration of three different optical functions on the substrate of the surface-emitting laser. First, a 40 level refractive microlens milled using focused ion beam shows a twofold reduction of the full-width half maximum 1mm above the device, showing potential for monolithic integration of coupling optics on the wafer. We then show that differential quantum efficiency of 65%, the highest reported for a grating-coupled device, can be achieved by lowering the substrate reflectivity using a 200nm period tapered subwavelength grating that has a grating wavevector oriented parallel to the electric field polarization. The low reflectivity structure shows trapezoidal sidewall profiles obtained using a soft mask erosion technique in a single etching step. Finally, we demonstrate that, unlike typical methods reported so far for in-plane beam-shaping of laser diodes, the integration of a beam-splitting element on the device substrate does not affect the device efficiency. The proposed device configuration can be tailored to satisfy a wide range of applications including high power pump lasers, superluminescent diodes, or optical amplifiers applications.
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Date Issued: 2004
Identifier: CFE0000223, ucf:46253
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000223

Title: DISCRETE NONLINEAR WAVE PROPAGATION IN KERR NONLINEAR MEDIA.
Creator: Meier, Joachim, Stegeman, George, University of Central Florida
Abstract / Description: Discrete optical systems are a subgroup of periodic structures in which the evolution of a continuous electromagnetic field can be described by a discrete model. In this model, the total field is the sum of localized, discrete modes. Weakly coupled arrays of single mode channel waveguides have been known to fall into this class of systems since the late 1960's. Nonlinear discrete optics has received a considerable amount of interest in the last few years, triggered by the experimental...
Show moreDiscrete optical systems are a subgroup of periodic structures in which the evolution of a continuous electromagnetic field can be described by a discrete model. In this model, the total field is the sum of localized, discrete modes. Weakly coupled arrays of single mode channel waveguides have been known to fall into this class of systems since the late 1960's. Nonlinear discrete optics has received a considerable amount of interest in the last few years, triggered by the experimental realization of discrete solitons in a Kerr nonlinear AlGaAs waveguide array by H. Eisenberg and coworkers in 1998. In this work a detailed experimental investigation of discrete nonlinear wave propagation and the interactions between beams, including discrete solitons, in discrete systems is reported for the case of a strong Kerr nonlinearity. The possibility to completely overcome "discrete" diffraction and create highly localized solitons, in a scalar or vector geometry, as well as the limiting factors in the formation of such nonlinear waves is discussed. The reversal of the sign of diffraction over a range of propagation angles leads to the stability of plane waves in a material with positive nonlinearity. This behavior can not be found in continuous self-focusing materials where plane waves are unstable against perturbations. The stability of plane waves in the anomalous diffraction region, even at highest powers, has been experimentally verified. The interaction of high power beams and discrete solitons in arrays has been studied in detail. Of particular interest is the experimental verification of a theoretically predicted unique, all optical switching scheme, based on the interaction of a so called "blocker" soliton with a second beam. This switching method has been experimentally realized for both the coherent and incoherent case. Limitations of such schemes due to nonlinear losses at the required high powers are shown.
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Date Issued: 2004
Identifier: CFE0000186, ucf:46176
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000186

Title: Mesoscale Light-Matter Interactions.
Creator: Douglass, Kyle, Dogariu, Aristide, Abouraddy, Ayman, Hagan, David, Sugaya, Kiminobu, University of Central Florida
Abstract / Description: Mesoscale optical phenomena occur when light interacts with a number of different types of materials, such as biological and chemical systems and fabricated nanostructures. As a framework, mesoscale optics unifies the interpretations of the interaction of light with complex media when the outcome depends significantly upon the scale of the interaction. Most importantly, it guides the process of designing an optical sensing technique by focusing on the nature and amount of information that can...
Show moreMesoscale optical phenomena occur when light interacts with a number of different types of materials, such as biological and chemical systems and fabricated nanostructures. As a framework, mesoscale optics unifies the interpretations of the interaction of light with complex media when the outcome depends significantly upon the scale of the interaction. Most importantly, it guides the process of designing an optical sensing technique by focusing on the nature and amount of information that can be extracted from a measurement.Different aspects of mesoscale optics are addressed in this dissertation which led to the solution of a number of problems in complex media. Dynamical and structural information from complex fluids(-)such as colloidal suspensions and biological fluids(-)was obtained by controlling the size of the interaction volume with low coherence interferometry. With this information, material properties such as particle sizes, optical transport coefficients, and viscoelastic characteristics of polymer solutions and blood were determined in natural, realistic conditions that are inaccessible to conventional techniques.The same framework also enabled the development of new, scale-dependent models for several important physical and biological systems. These models were then used to explain the results of some unique measurements. For example, the transport of light in disordered photonic lattices was interpreted as a scale-dependent, diffusive process to explain the anomalous behavior of photon path length distributions through these complex structures. In addition, it was demonstrated how specialized optical measurements and models at the mesoscale enable solutions to fundamental problems in cell biology. Specifically, it was found for the first time that the nature of cell motility changes markedly with the curvature of the substrate that the cellsivmove on. This particular work addresses increasingly important questions concerning the nature of cellular responses to external forces and the mechanical properties of their local environment.Besides sensing of properties and modeling behaviors of complex systems, mesoscale optics encompasses the control of material systems as a result of the light-matter interaction. Specific modifications to a material's structure can occur due to not only an exchange of energy between radiation and a material, but also due to a transfer of momentum. Based on the mechanical action of multiply scattered light on colloidal particles, an optically-controlled active medium that did not require specially tailored particles was demonstrated for the first time. The coupling between the particles and the random electromagnetic field affords new possibilities for controlling mesoscale systems and observing nonequilibrium thermodynamic phenomena.
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Date Issued: 2013
Identifier: CFE0004990, ucf:49606
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004990

Title: Monolithically Integrated InP-based Unidirectional Circulators Utilizing non-Hermiticity and Nonlinearity.
Creator: Aleahmad, Parinaz, Christodoulides, Demetrios, Delfyett, Peter, Likamwa, Patrick, Moya Cessa, Hector Manual, University of Central Florida
Abstract / Description: The need to integrate critical optical components on a single chip has been an ongoing quest in both optoelectronics and optical communication systems. Among the possible devices, elements supporting non-reciprocal transmission are of great interest for applications where signal routing and isolation is required. In this respect, breaking reciprocity is typically accomplished via Faraday rotation through appropriate magneto-optical arrangements. Unfortunately, standard light emitting...
Show moreThe need to integrate critical optical components on a single chip has been an ongoing quest in both optoelectronics and optical communication systems. Among the possible devices, elements supporting non-reciprocal transmission are of great interest for applications where signal routing and isolation is required. In this respect, breaking reciprocity is typically accomplished via Faraday rotation through appropriate magneto-optical arrangements. Unfortunately, standard light emitting optoelectronic materials like for example III-V semiconductors, lack magneto-optical properties and hence cannot be directly used in this capacity. To address these issues, a number of different tactics have been attempted in the last few years. These range from directly bonding garnets on chip, to parametric structures and unidirectional nonlinear arrangements involving ring resonators, to mention a few. Clearly, of importance will be to realize families of non-reciprocal devises that not only can be miniaturized and readily integrated on chip but they also rely on physical processes that are indigenous to the semiconductor wafer itself. Quite recently we have theoretically shown that such unidirectional systems can be implemented, provided one simultaneously exploits the presence of gain/loss processes and optical nonlinearities. In principle, these all-dielectric structures can be broadband, polarization insensitive, color-preserving, and can display appreciable isolation ratios provided they are used under pulsed conditions. In this study, we experimentally demonstrate a compact, monolithically integrated unidirectional 4(&)#215;4 optical circulator, based on non-reciprocal optical transmission through successive amplification/attenuation stages and elements with very large resonance nonlinearities associated with InGaAsP quantum wells. Our results indicate that isolation ratios over 20dB can be experimentally achieved in pulse-mode operation. Our design can be effortlessly extended to other existing optoelectronic device systems beyond InP.
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Date Issued: 2016
Identifier: CFE0006522, ucf:51373
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006522

Title: SYSTEM DESIGN AND OPTIMIZATION OF OPTICAL COHERENCE TOMOGRAPHY.
Creator: Akcay, Avni, Rolland, Jannick, University of Central Florida
Abstract / Description: Optical coherence imaging, including tomography (OCT) and microscopy (OCM), has been a growing research field in biomedical optical imaging in the last decade. In this imaging modality, a broadband light source, thus of short temporal coherence length, is used to perform imaging via interferometry. A challenge in optical coherence imaging, as in any imaging system towards biomedical diagnosis, is the quantification of image quality and optimization of the system components, both a primary...
Show moreOptical coherence imaging, including tomography (OCT) and microscopy (OCM), has been a growing research field in biomedical optical imaging in the last decade. In this imaging modality, a broadband light source, thus of short temporal coherence length, is used to perform imaging via interferometry. A challenge in optical coherence imaging, as in any imaging system towards biomedical diagnosis, is the quantification of image quality and optimization of the system components, both a primary focus of this research. We concentrated our efforts on the optimization of the imaging system from two main standpoints: axial point spread function (PSF) and practical steps towards compact low-cost solutions. Up to recently, the criteria for the quality of a system was based on speed of imaging, sensitivity, and particularly axial resolution estimated solely from the full-width at half-maximum (FWHM) of the axial PSF with the common practice of assuming a Gaussian source power spectrum. As part of our work to quantify axial resolution we first brought forth two more metrics unlike FWHM, which accounted for side lobes in the axial PSF caused by irregularities in the shape of the source power spectrum, such as spectral dips. Subsequently, we presented a method where the axial PSF was significantly optimized by suppressing the side lobes occurring because of the irregular shape of the source power spectrum. The optimization was performed through optically shaping the source power spectrum via a programmable spectral shaper, which consequentially led to suppression of spurious structures in the images of a layered specimen. The superiority of the demonstrated approach was in performing reshaping before imaging, thus eliminating the need for post-data acquisition digital signal processing. Importantly, towards the optimization and objective image quality assessment in optical coherence imaging, the impact of source spectral shaping was further analyzed in a task-based assessment method based on statistical decision theory. Two classification tasks, a signal-detection task and a resolution task, were investigated. Results showed that reshaping the source power spectrum was a benefit essentially to the resolution task, as opposed to both the detection and resolution tasks, and the importance of the specimen local variations in index of refraction on the resolution task was demonstrated. Finally, towards the optimization of OCT and OCM for use in clinical settings, we analyzed the detection electronics stage, which is a crucial component of the system that is designed to capture extremely weak interferometric signals in biomedical and biological imaging applications. We designed and tested detection electronics to achieve a compact and low-cost solution for portable imaging units and demonstrated that the design provided an equivalent performance to the commercial lock-in amplifier considering the system sensitivity obtained with both detection schemes.
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Date Issued: 2005
Identifier: CFE0000651, ucf:46527
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000651

Title: INTERFEROMETRY-BASED FREE SPACE COMMUNICATION AND INFORMATION PROCESSING.
Creator: Arain, Muzamil, Riza, Nabeel, University of Central Florida
Abstract / Description: This dissertation studies, analyzes, and experimentally demonstrates the innovative use of interference phenomenon in the field of opto-electronic information processing and optical communications. A number of optical systems using interferometric techniques both in the optical and the electronic domains has been demonstrated in the filed of signal transmission and processing, optical metrology, defense, and physical sensors. Specifically it has been shown that the interference of waves in...
Show moreThis dissertation studies, analyzes, and experimentally demonstrates the innovative use of interference phenomenon in the field of opto-electronic information processing and optical communications. A number of optical systems using interferometric techniques both in the optical and the electronic domains has been demonstrated in the filed of signal transmission and processing, optical metrology, defense, and physical sensors. Specifically it has been shown that the interference of waves in the form of holography can be exploited to realize a novel optical scanner called Code Multiplexed Optical Scanner (C-MOS). The C-MOS features large aperture, wide scan angles, 3-D beam control, no moving parts, and high beam scanning resolution. A C-MOS based free space optical transceiver for bi-directional communication has also been experimentally demonstrated. For high speed, large bandwidth, and high frequency operation, an optically implemented reconfigurable RF transversal filter design is presented that implements wide range of filtering algorithms. A number of techniques using heterodyne interferometry via acousto-optic device for optical path length measurements have been described. Finally, a whole new class of interferometric sensors for optical metrology and sensing applications is presented. A non-traditional interferometric output signal processing scheme has been developed. Applications include, for example, temperature sensors for harsh environments for a wide temperature range from room temperature to 1000 degree C.
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Date Issued: 2005
Identifier: CFE0000598, ucf:46478
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000598

Title: POLARIMETRY OF RANDOM FIELDS.
Creator: Ellis, Jeremy, Dogariu, Aristide, University of Central Florida
Abstract / Description: On temporal, spatial and spectral scales which are small enough, all fields are fully polarized. In the optical regime, however, instantaneous fields can rarely be examined, and, instead, only average quantities are accessible. The study of polarimetry is concerned with both the description of electromagnetic fields and the characterization of media a field has interacted with. The polarimetric information is conventionally presented in terms of second order field correlations which are...
Show moreOn temporal, spatial and spectral scales which are small enough, all fields are fully polarized. In the optical regime, however, instantaneous fields can rarely be examined, and, instead, only average quantities are accessible. The study of polarimetry is concerned with both the description of electromagnetic fields and the characterization of media a field has interacted with. The polarimetric information is conventionally presented in terms of second order field correlations which are averaged over the ensemble of field realizations. Motivated by the deficiencies of classical polarimetry in dealing with specific practical situations, this dissertation expands the traditional polarimetric approaches to include higher order field correlations and the description of fields fluctuating in three dimensions. In relation to characterization of depolarizing media, a number of fourth-order correlations are introduced in this dissertation. Measurements of full polarization distributions, and the subsequent evaluation of Stokes vector element correlations and Complex Degree of Mutual Polarization demonstrate the use of these quantities for material discrimination and characterization. Recent advancements in detection capabilities allow access to fields near their sources and close to material boundaries, where a unique direction of propagation is not evident. Similarly, there exist classical situations such as overlapping beams, focusing, or diffusive scattering in which there is no unique transverse direction. In this dissertation, the correlation matrix formalism is expanded to describe three dimensional electromagnetic fields, providing a definition for the degree of polarization of such a field. It is also shown that, because of the dimensionality of the problem, a second parameter is necessary to fully describe the polarimetric properties of three dimensional fields. Measurements of second-order correlations of a three dimensional field are demonstrated, allowing the determination of both the degree of polarization and the state of polarization. These new theoretical concepts and innovative experimental approaches introduced in thiss dissertation are expected to impact scientific areas as diverse as near field optics, remote sensing, high energy laser physics, fluorescence microscopy, and imaging.
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Date Issued: 2006
Identifier: CFE0000982, ucf:46697
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000982

Title: DESIGN AND ANALYSIS OF EFFECTIVE ROUTING AND CHANNEL SCHEDULING FOR WAVELENGTH DIVISION MULTIPLEXING OPTICAL NETWORKS.
Creator: Gao, Xingbo, Bassiouni, Mostafa, University of Central Florida
Abstract / Description: Optical networking, employing wavelength division multiplexing (WDM), is seen as the technology of the future for the Internet. This dissertation investigates several important problems affecting optical circuit switching (OCS) and optical burst switching (OBS) networks. Novel algorithms and new approaches to improve the performance of these networks through effective routing and channel scheduling are presented. Extensive simulations and analytical modeling have both been used to evaluate...
Show moreOptical networking, employing wavelength division multiplexing (WDM), is seen as the technology of the future for the Internet. This dissertation investigates several important problems affecting optical circuit switching (OCS) and optical burst switching (OBS) networks. Novel algorithms and new approaches to improve the performance of these networks through effective routing and channel scheduling are presented. Extensive simulations and analytical modeling have both been used to evaluate the effectiveness of the proposed algorithms in achieving lower blocking probability, better fairness as well as faster switching. The simulation tests were performed over a variety of optical network topologies including the ring and mesh topologies, the U.S. Long-Haul topology, the Abilene high-speed optical network used in Internet 2, the Toronto Metropolitan topology and the European Optical topology. Optical routing protocols previously published in the literature have largely ignored the noise and timing jitter accumulation caused by cascading several wavelength conversions along the lightpath of the data burst. This dissertation has identified and evaluated a new constraint, called the wavelength conversion cascading constraint. According to this constraint, the deployment of wavelength converters in future optical networks will be constrained by a bound on the number of wavelength conversions that a signal can go through when it is switched all-optically from the source to the destination. Extensive simulation results have conclusively demonstrated that the presence of this constraint causes significant performance deterioration in existing routing and wavelength assignment (RWA) algorithms. Higher blocking probability and/or worse fairness have been observed for existing RWA algorithms when the cascading constraint is not ignored. To counteract the negative side effect of the cascading constraint, two constraint-aware routing algorithms are proposed for OCS networks: the desirable greedy algorithm and the weighted adaptive algorithm. The two algorithms perform source routing using link connectivity and the global state information of each wavelength. Extensive comparative simulation results have illustrated that by limiting the negative cascading impact to the minimum extent practicable, the proposed approaches can dramatically decrease the blocking probability for a variety of optical network topologies. The dissertation has developed a suite of three fairness-improving adaptive routing algorithms in OBS networks. The adaptive routing schemes consider the transient link congestion at the moment when bursts arrive and use this information to reduce the overall burst loss probability. The proposed schemes also resolve the intrinsic unfairness defect of existing popular signaling protocols. The extensive simulation results have shown that the proposed schemes generally outperform the popular shortest path routing algorithm and the improvement could be substantial. A two-dimensional Markov chain analytical model has also been developed and used to analyze the burst loss probabilities for symmetrical ring networks. The accuracy of the model has been validated by simulation. Effective proactive routing and preemptive channel scheduling have also been proposed to address the conversion cascading constraint in OBS environments. The proactive routing adapts the fairness-improving adaptive routing mentioned earlier to the environment of cascaded wavelength conversions. On the other hand, the preemptive channel scheduling approach uses a dynamic priority for each burst based on the constraint threshold and the current number of performed wavelength conversions. Empirical results have proved that when the cascading constraint is present, both approaches would not only decrease the burst loss rates greatly, but also improve the transmission fairness among bursts with different hop counts to a large extent.
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Date Issued: 2009
Identifier: CFE0002965, ucf:47958
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002965

Title: MICRO-ELECTRO-MECHANICAL SYSTEMS (MEMS) AND AGILE LENSING-BASED MODULES FOR COMMUNICATIONS, SENSING AND SIGNAL PROCESSING.
Creator: Reza, Syed, Riza, Nabeel, University of Central Florida
Abstract / Description: This dissertation proposes the use of the emerging Micro-Electro-Mechanical Systems (MEMS) and agile lensing optical device technologies to design novel and powerful signal conditioning and sensing modules for advanced applications in optical communications, physical parameter sensing and RF/optical signal processing. For example, these new module designs have experimentally demonstrated exceptional features such as stable loss broadband operations and high > 60 dB optical dynamic range...
Show moreThis dissertation proposes the use of the emerging Micro-Electro-Mechanical Systems (MEMS) and agile lensing optical device technologies to design novel and powerful signal conditioning and sensing modules for advanced applications in optical communications, physical parameter sensing and RF/optical signal processing. For example, these new module designs have experimentally demonstrated exceptional features such as stable loss broadband operations and high > 60 dB optical dynamic range signal filtering capabilities. The first part of the dissertation describes the design and demonstration of digital MEMS-based signal processing modules for communication systems and sensor networks using the TI DLP (Digital Light Processing) technology. Examples of such modules include optical power splitters, narrowband and broadband variable fiber optical attenuators, spectral shapers and filters. Compared to prior works, these all-digital designs have advantages of repeatability, accuracy, and reliability that are essential for advanced communications and sensor applications. The next part of the dissertation proposes, analyzes and demonstrates the use of analog opto-fluidic agile lensing technology for sensor networks and test and measurement systems. Novel optical module designs for distance sensing, liquid level sensing, three-dimensional object shape sensing and variable photonic delay lines are presented and experimentally demonstrated. Compared to prior art module designs, the proposed analog-mode modules have exceptional performances, particularly for extreme environments (e.g., caustic liquids) where the free-space agile beam-based sensor provide remote non-contact access for physical sensing operations. The dissertation also presents novel modules involving hybrid analog-digital photonic designs that make use of the different optical device technologies to deliver the best features of both analog and digital optical device operations and controls. Digital controls are achieved through the use of the digital MEMS technology and analog controls are realized by employing opto-fluidic agile lensing technology and acousto-optic technology. For example, variable fiber-optic attenuators and spectral filters are proposed using the hybrid design. Compared to prior art module designs, these hybrid designs provide a higher module dynamic range and increased resolution that are critical in various advanced system applications. In summary, the dissertation shows the added power of hybrid optical designs using both the digital and analog photonic signal processing versus just all-digital or all-analog module designs.
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Date Issued: 2010
Identifier: CFE0003143, ucf:48644
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003143

Title: ELECTROMAGNETIC PROPAGATION ANOMALIES IN WAVEGUIDING STRUCTURES AND SCATTERING SYSTEMS.
Creator: Salandrino, Alessandro, Christodoulides, Demetrios, University of Central Florida
Abstract / Description: The effects related to diffraction and interference are ubiquitous in phenomena involving electromagnetic wave propagation, and are accurately predicted and described within the framework of classical electrodynamics. In the vast majority of the cases the qualitative features of the evolution of a propagating wave can be inferred even without detailed calculations. A field distribution will spread upon propagation, will accumulate phase along the direction of power flow, will exert mechanical...
Show moreThe effects related to diffraction and interference are ubiquitous in phenomena involving electromagnetic wave propagation, and are accurately predicted and described within the framework of classical electrodynamics. In the vast majority of the cases the qualitative features of the evolution of a propagating wave can be inferred even without detailed calculations. A field distribution will spread upon propagation, will accumulate phase along the direction of power flow, will exert mechanical forces upon scattering objects in the direction of propagation etc. When such predictions fail, counterintuitive effects and new functionalities can be engineered. In this work a series of exceptional cases under different degrees of field confinement have been isolated. In such instances the electromagnetic behavior significantly deviates from conventional cases. In particular, considering structures with monodimensional field confinement, the only possible class of diffraction free surface waves has been introduced. Again within the context of surface waves the mechanism of Enhanced Evanescent Tunneling (EET) has been proposed, which allows a net power flow to be sustained by evanescent fields only with applications to sub-diffraction imaging. Increasing the degree of field confinement, a unique class of fully dielectric waveguide arrays able to support negative effective index modes has been theoretically demonstrated. Finally the opto-mechanical consequences of such effective negative index environments have been studied, highlighting counterintuitive properties. Instrumental to these findings was the introduction of a general theory of optical forces in terms of vector spherical harmonics.
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Date Issued: 2011
Identifier: CFE0003930, ucf:48691
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003930

Title: PHOTODISRUPTION IN OCULAR TISSUE NEAR AND AT THE BOUNDARY BETWEEN THE ANTERIOR CHAMBER AND CRYSTALLINE LENS.
Creator: Olmstead, Richard, Richardson, Martin, University of Central Florida
Abstract / Description: Lasers have been involved in Ophthalmology in the treatment of myopia and hyperopia for several years. Laser systems have transformed patients' quality of life, freeing them from the need for glasses, as in the case of LASIK. Ultrafast lasers have played an important role in surgery of the eye. In LASIK, they are used to cut the flap that is lifted to expose the stroma for UV Excimer laser treatment of this region. They are now being used for surgery deeper into the eye,for instance, treating...
Show moreLasers have been involved in Ophthalmology in the treatment of myopia and hyperopia for several years. Laser systems have transformed patients' quality of life, freeing them from the need for glasses, as in the case of LASIK. Ultrafast lasers have played an important role in surgery of the eye. In LASIK, they are used to cut the flap that is lifted to expose the stroma for UV Excimer laser treatment of this region. They are now being used for surgery deeper into the eye,for instance, treating the lens as part of treatments for cataract surgery. The use of ultrafast lasers in cataract surgery and how they can be applied to achieve better surgical outcomes is the focus of this work. It reports on an investigation of laser interaction at and near the anterior of the lens, in particular the boundary between the fibrous mass, capsule, and anterior chamber of the eye. The study reviews the biomechanics of the eye, develops an interaction model with lens tissue, and reports for the first time clinically studies using ex vivo testing of porcine eyes. The components of the treatment laser system are described along with the requirements. Results of the experiments are outlined and discussed, followed by a summary and conclusions including discussion of areas for further research.
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Date Issued: 2011
Identifier: CFE0003658, ucf:48817
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003658

Title: Third Order Nonlinearity of Organic Molecules.
Creator: Hu, Honghua, Vanstryland, Eric, Hagan, David, Zeldovich, Boris, Hernandez, Florencio, University of Central Florida
Abstract / Description: The main goal of this dissertation is to investigate the third-order nonlinearity of organic molecules. This topic contains two aspects: two-photon absorption (2PA) and nonlinear refraction (NLR), which are associated with the imaginary and real part of the third-order nonlinearity (?(3)) of the material, respectively. With the optical properties tailored through meticulous molecular structure engineering, organic molecules are promising candidates to exhibit large third-order nonlinearities....
Show moreThe main goal of this dissertation is to investigate the third-order nonlinearity of organic molecules. This topic contains two aspects: two-photon absorption (2PA) and nonlinear refraction (NLR), which are associated with the imaginary and real part of the third-order nonlinearity (?(3)) of the material, respectively. With the optical properties tailored through meticulous molecular structure engineering, organic molecules are promising candidates to exhibit large third-order nonlinearities. Both linear (absorption, fluorescence, fluorescence excitation anisotropy) and nonlinear (Z-scan, two-photon fluorescence, pump-probe) techniques are described and utilized to fully characterize the spectroscopic properties of organic molecules in solution or solid-state form. These properties are then analyzed by quantum chemical calculations or other specific quantum mechanical model to understand the origins of the nonlinearities as well as the correlations with their unique molecular structural features. These calculations are performed by collaborators. The 2PA study of organic materials is focused on the structure-2PA property relationships of four groups of dyes with specific molecular design approaches as the following: (1) Acceptor-?-Acceptor dyes for large 2PA cross section, (2) Donor-?-Acceptor dyes for strong solvatochromic effects upon the 2PA spectra, (3) Near-infrared polymethine dyes for a symmetry breaking effect, (4) Sulfur-squaraines vs. oxygen-squaraines to study the role of sulfur atom replacement upon their 2PA spectra. Additionally, the 2PA spectrum of a solid-state single crystal made from a Donor-?-Acceptor dye is measured, and the anisotropic nonlinearity is studied with respect to different incident polarizations. These studies further advance our understanding towards an ultimate goal to a predictive capability for the 2PA properties of organic molecules. The NLR study on molecules is focused on the temporal and spectral dispersion of the nonlinear refraction index, n2, of the molecules. Complicated physical mechanisms, originating from either electronic transitions or nuclei movement, are introduced in general. By adopting a prism compressor / stretcher to control the pulsewidth, an evolution of n2 with respect to incident pulsewidth is measured on a simple inorganic molecule (-)carbon disulfide (CS2) in neat liquid at 700 nm and 1064 nm to demonstrate the pulsewidth dependent nonlinear refraction. The n2 spectra of CS2 and certain organic molecules are measured by femtosecond pulses, which are then analyzed by a 3-level model, a simplified (")Sum-over-states(") quantum mechanical model. These studies can serve as a precursor for future NLR investigations.
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Date Issued: 2012
Identifier: CFE0004387, ucf:49400
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004387

Title: Mesoscopic Interactions in Complex Photonic Media.
Creator: Rezvani Naraghi, Roxana, Dogariu, Aristide, Tetard, Laurene, Rahman, Talat, Abouraddy, Ayman, University of Central Florida
Abstract / Description: Mesoscale optics provides a framework for understanding a wide range of phenomena occurring in a variety of fields ranging from biological tissues to composite materials and from colloidal physics to fabricated nanostructures. When light interacts with a complex system, the outcome depends significantly on the length and time scales of interaction. Mesoscale optics offers the apparatus necessary for describing specific manifestations of wave phenomena such as interference and phase memory in...
Show moreMesoscale optics provides a framework for understanding a wide range of phenomena occurring in a variety of fields ranging from biological tissues to composite materials and from colloidal physics to fabricated nanostructures. When light interacts with a complex system, the outcome depends significantly on the length and time scales of interaction. Mesoscale optics offers the apparatus necessary for describing specific manifestations of wave phenomena such as interference and phase memory in complex media. In-depth understanding of mesoscale phenomena provides the required quantitative explanations that neither microscopic nor macroscopic models of light-matter interaction can afford. Modeling mesoscopic systems is challenging because the outcome properties can be efficiently modified by controlling the extent and the duration of interactions.In this dissertation, we will first present a brief survey of fundamental concepts, approaches, and techniques specific to fundamental light-matter interaction at mesoscopic scales. Then, we will discuss different regimes of light propagation through randomly inhomogenous media. In particular, a novel description will be introduced to analyze specific aspects of light propagation in dense composites. Moreover, we will present evidence that the wave nature of light can be critical for understanding its propagation in unbounded highly scattering materials. We will show that the perceived diffusion of light is subjected to competing mechanisms of interaction that lead to qualitatively different phases for the light evolution through complex media. In particular, we will discuss implications on the ever elusive localization of light in three-dimensional random media. In addition to fundamental aspects of light-matter interaction at mesoscopic scales, this dissertation will also address the process of designing material structures that provide unique scattering properties. We will demonstrate that multi-material dielectric particles with controlled radial and azimuthal structure can be engineered to modify the extinction cross-section, to control the scattering directivity, and to provide polarization-dependent scattering. We will show that dielectric core-shell structures with similar macroscopic sizes can have both high scattering cross-sections and radically different scattering phase functions. In addition, specific structural design, which breaks the azimuthal symmetry of the spherical particle, can be implemented to control the polarization properties of scattered radiation. Moreover, we will also demonstrate that the power flow around mesoscopic scattering particles can be controlled by modifying their internal heterogeneous structures.Lastly, we will show how the statistical properties of the radiation emerging from mesoscopic systems can be utilized for surface and subsurface diagnostics. In this dissertation, we will demonstrate that the intensity distributions measured in the near-field of composite materials are direct signatures of the scale-dependent morphology, which is determined by variations of the local dielectric function. We will also prove that measuring the extent of spatial coherence in the proximity of two-dimensional interfaces constitutes a rather general method for characterizing the defect density in crystalline materials. Finally, we will show that adjusting the spatial coherence properties of radiation can provide a simple solution for a significant deficiency of near-field microscopy. We will demonstrate experimentally that spurious interference effects can be efficiently eliminated in passive near-field imaging by implementing a random illumination.
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Date Issued: 2017
Identifier: CFE0006647, ucf:51253
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006647

$Ultrafast Mechanisms of Nonlinear Refraction and Two-photon Photochromism$

Title: Ultrafast Mechanisms of Nonlinear Refraction and Two-photon Photochromism.
Creator: Zhao, Peng, Hagan, David, Vanstryland, Eric, Christodoulides, Demetrios, Hernandez, Florencio, University of Central Florida
Abstract / Description: Derived from a material's third-order nonlinearity, nonlinear refraction (NLR) occurs at any wavelength in any material, and may exhibit noninstantaneous dynamics depending on its physical origins. The main subject of this dissertation is to investigate the underlying mechanisms responsible for the NLR response in different phases of matter, e.g. liquids, gases, and semiconductors, by extensively using our recently developed ultrafast Beam Deflection (BD) technique. An additional subject...
Show moreDerived from a material's third-order nonlinearity, nonlinear refraction (NLR) occurs at any wavelength in any material, and may exhibit noninstantaneous dynamics depending on its physical origins. The main subject of this dissertation is to investigate the underlying mechanisms responsible for the NLR response in different phases of matter, e.g. liquids, gases, and semiconductors, by extensively using our recently developed ultrafast Beam Deflection (BD) technique. An additional subject includes the characterization of a novel two-photon photochromic molecule.In molecular liquids, the major nonlinear optical (NLO) response can be decomposed into a nearly instantaneous bound-electronic NLR (Kerr effect), originating from the real part the electronic second hyperpolarizability, ?, and noninstantaneous mechanisms due to nuclear motions. By adopting the methodology previously developed for carbon disulfide (CS2), we have measured the NLO response functions of 23 common organic solvents, providing a database of magnitudes and temporal dynamics of each mechanism, which can be used for predicting the outcomes of any other NLR related experiments such as Z-scan. Also, these results provide insight to relate solvent nonlinearities with their molecular structures as well as linear polarizability tensors. In the measurements of air and gaseous CS2, coherent Raman excitation of many rotational states manifests as revivals in the transient NLR, from which we identify N2, O2 and two isotopologues of CS2, and unambiguously determine the dephasing rate, and rotational and centrifugal constants of each constituent. Using the revival signal as a self-reference, ? is directly measured for CS2 molecules in gas phase, which coincides with the ? determined from liquid phase measurements when including the Lorentz-Lorenz local field correction. In semiconductors, the Kerr effect dominates the NLR in the sub-gap regime. Here, we primarily focus on investigating the dispersion of nondegenerate (ND) NLR, namely the refractive index change at frequency ?_a due to the presence of a beam at frequency ?_b. The magnitude and sign of the ND-NLR coefficient n_2 (?_a;?_b ) are determined for ZnO, ZnSe and CdS over a broad spectral range for different values of nondegeneracy, which closely follows our earlier predictions based on nonlinear Kramers-Kronig relations. In the extremely nondegenerate case, n_2 (?_a;?_b ) is positively enhanced near the two-photon absorption (2PA) edge, suggesting applications for nondegenerate all-optical switching. Additionally, n_2 (?_a;?_b ) exhibits a strong anomalous nonlinear dispersion within the ND-2PA spectral region, providing a large phase modulation of a femtosecond pulse with bandwidth centered near the zero-crossing frequency. Another subject of this dissertation is the characterization of a spiro-type two-photon photochromic molecule, in which F(&)#246;rster resonance energy transfer (FRET) is utilized to activate the ring-opening effect from a 2PA-donor chromophore. Evidence of energy transfer is observed via fluorescence measurements of the quantum yield, excitation spectra and anisotropy. The absorption and lifetime of the open form are measured in a dye-doped sol-gel matrix. Transient absorption measurements indicate both ring opening and closing occurs on a several picosecond time scale along with multiple transient photoproducts, from which a high FRET efficiency is measured in agreement with theoretical predictions. This efficient 2PA-FRET photochrome may be implemented into photonic devices such as optical memories. However, with a relatively small open-form absorption cross section and significant ring closing, the photochrome may not be viable for enhancing nonlinear absorption in applications such as optical limiting.
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Date Issued: 2016
Identifier: CFE0006517, ucf:51370
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006517

Title: Novel optical properties of metal nanostructures based on surface plasmons.
Creator: Wang, Haining, Zou, Shengli, Liao, Yi, Kolpashchikov, Dmitry, Gesquiere, Andre, Su, Ming, University of Central Florida
Abstract / Description: Surface plasmons have been attracted extensive interests in recent decades due to the novel properties in nanometer sized dimensions. My work focused on the novel optical properties of metal nanostructures based on surface plasmons using theoretical simulation methods. In the first part, we investigated metal nanofilms and nanorods and demonstrated that extremely low scattering efficiency, high absorption efficiency and propagation with long distance could be obtained by different metal...
Show moreSurface plasmons have been attracted extensive interests in recent decades due to the novel properties in nanometer sized dimensions. My work focused on the novel optical properties of metal nanostructures based on surface plasmons using theoretical simulation methods. In the first part, we investigated metal nanofilms and nanorods and demonstrated that extremely low scattering efficiency, high absorption efficiency and propagation with long distance could be obtained by different metal nanostructures. With a perforated silver film, we demonstrated that an extremely low scattering cross section with an efficiency of less than 1% can be achieved at tunable wavelengths with tunable widths. The resonance wavelength, width, and intensity are influenced by the shape, size and arrangement pattern of the holes, as well as the distance separating the holes along the polarization direction. The extremely low scattering could be used to obtain high absorption efficiency of a two-layer silver nanofilm. Using the discrete dipole approximation method, we achieved enhanced absorption efficiencies, which are close to 100%, at tunable wavelengths in a two-layer silver thin film. The film is composed of a 100 nm thick perforated layer facing the incident light and a 100 nm thick solid layer. Resonance wavelengths are determined by the distances between perforated holes in the first layer as well as the separation between two layers. The resonance wavelengths shift to red with increasing separation distance between two layers or the periodic distance of the hole arrays. Geometries of conical frustum shaped holes in the first layer are critical for the improved absorption efficiencies. When the hole bottom diameter equals the periodic distance and the upper diameter is about one-third of the bottom diameter, close to unit absorption efficiency can be obtained. We examined the electromagnetic wave propagation along a hollow silver nanorod with subwavelength dimensions. The calculations show that light may propagate along the hollow nanorod with growing intensities. The influences of the shape, dimension, and length of the rod on the resonance wavelength and the enhanced local electric field, |E|2, along the rod were investigated. In the second part, a generalized electrodynamics model is proposed to describe the enhancement and quenching of fluorescence signal of a dye molecule placed near a metal nanoparticle (NP). Both the size of the Au NPs and quantum yield of the dye molecule are crucial in determining the emission intensity of the molecule. Changing the size of the metal NP will alter the ratio of the scattering and absorption efficiencies of the metal NP and consequently result in different enhancement or quenching effect to the dye molecule. A dye molecule with a reduced quantum yield indicates that the non-radiative channel is dominant in the decay of the excited dye molecules and the amplification of the radiative decay rate will be easier. In general, the emission intensity will be quenched when the size of metal NP is small and the quantum yield of dye molecule is about unity. A significant enhancement factor will be obtained when the quantum yield of the molecule is small and the particle size is large. When the quantum yield of the dye molecule is less than 10-5, the model is simplified to the surface enhanced Raman scattering equation.
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Date Issued: 2013
Identifier: CFE0004769, ucf:49786
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004769

Title: fast-response liquid crystals for photonic and display applications.
Creator: Sun, Jie, Wu, Shintson, Likamwa, Patrick, Schoenfeld, Winston, Wu, Xinzhang, University of Central Florida
Abstract / Description: Liquid crystals (LCs) are attractive for many applications such as information displays, spatial light modulators, and adaptive optics because the optical properties of these devices are electrically tunable. For most display and photonic applications, response time is a critical parameter especially for spatial light modulators that requires at least 2? phase change. This problem gets more severe as the wavelength increases because a thicker LC layer is needed, which results in a slower...
Show moreLiquid crystals (LCs) are attractive for many applications such as information displays, spatial light modulators, and adaptive optics because the optical properties of these devices are electrically tunable. For most display and photonic applications, response time is a critical parameter especially for spatial light modulators that requires at least 2? phase change. This problem gets more severe as the wavelength increases because a thicker LC layer is needed, which results in a slower response time. A typical E7 nematic liquid crystal cell with 2? phase change shows a response time longer than 100 ms at room temperature, which is too slow. Therefore, solutions for achieving fast response time are in high demand.In this dissertation, several approaches for achieving submillisecond response time are investigated. In Chapter 2, we begin by introducing dual frequency liquid crystals (DFLCs) which provide possibility to achieve submillisecond rise time and decay time. We developed a DFLC mixture with a record-high birefringence (?n=0.39 at ?=633nm) based on phenyl-tolane compounds, which exhibit a positive dielectric anisotropy (??) and modest dielectric relaxation frequency. In Chapter 3, a phase modulator with 4? phase change and 400 (&)#181;s average gray-to-gray response time is demonstrated using a sheared polymer network liquid crystal (SPNLC). This device exhibits a low scattering at ?=532 nm due to the employed material set and shearing technique. We also discuss the application of SPNLCs for 3D displays.In Chapter 4, we studied the temperature effect on the splay elastic constant of polymer network liquid crystal (PNLC). Due to the existence of polymer network, the temperature dependent splay elastic constant of the LC cell deviates from the model for nematic LCs. In Chapter 5, we focus on PNLC light modulators. This technology is attractive because it can achieve submillisecond response time while maintaining a large phase change. However, the light scattering loss caused by grain boundaries of liquid crystal multi-domains at voltage-on state hinders the widespread application of PNLCs. By optimizing liquid crystal host, polymer, and proper curing process, we successfully eliminate light scattering from short wave infrared region (1.55 ?m) to visible range. In Chapter 6, we introduce a reconfigurable fabrication technique of tunable liquid crystal devices. Based on this technique and our scattering-free PNLCs, we developed a series of fast switching LC devices such as LC prism, grating and lens. The application of this technology in 3D lenticular lens development is also discussed. This technique provides a great flexibility for designing and fabricating LC photonic devices with desired refractive index profile.
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Date Issued: 2013
Identifier: CFE0005063, ucf:49968
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005063

Title: Inverse Problems in Multiple Light Scattering.
Creator: Broky, John, Dogariu, Aristide, Christodoulides, Demetrios, Wu, Shintson, Tamasan, Alexandru, University of Central Florida
Abstract / Description: The interaction between coherent waves and material systems with complex optical properties is a complicated, deterministic process. Light that scatters from such media gives rise to random fields with intricate properties. It is common perception that the randomness of these complex fields is undesired and therefore is to be removed, usually through a process of ensemble averaging. However, random fields emerging from light matter interaction contain information about the properties of the...
Show moreThe interaction between coherent waves and material systems with complex optical properties is a complicated, deterministic process. Light that scatters from such media gives rise to random fields with intricate properties. It is common perception that the randomness of these complex fields is undesired and therefore is to be removed, usually through a process of ensemble averaging. However, random fields emerging from light matter interaction contain information about the properties of the medium and a thorough analysis of the scattered light allows solving specific inverse problems. Traditional attempts to solve these kinds of inverse problems tend to rely on statistical average quantities and ignore the deterministic interaction between the optical field and the scattering structure. Thus, because ensemble averaging inherently destroys specific characteristics of random processes, one can only recover limited information about the medium. This dissertation discusses practical means that go beyond ensemble averaging to probe complex media and extract additional information about a random scattering system. The dissertation discusses cases in which media with similar average properties can be differentiated by detailed examination of fluctuations between different realizations of the random process of multiple scattering. As a different approach to this type of inverse problems, the dissertation also includes a description of how higher-order field and polarization correlations can be used to extract features of random media and complex systems from one single realization of the light-matter interaction. Examples include (i) determining the level of multiple scattering, (ii) identifying non-stationarities in random fields, and (iii) extracting underlying correlation lengths of random electromagnetic fields that result from basic interferences. The new approaches introduced and the demonstrations described in this dissertation represent practical means to extract important material properties or to discriminate between media with similar characteristics even in situations when experimental constraints limit the number of realizations of the complex light-matter interaction.
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Date Issued: 2012
Identifier: CFE0004656, ucf:49888
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004656

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)	+ -
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Christodoulides, Demetrios (24)	+ -
Delfyett, Peter (23)	+ -
Likamwa, Patrick (22)	+ -
Li, Guifang (17)	+ -

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Dogariu, Aristide (13)	+ -
Hagan, David (12)	+ -
Peale, Robert (11)	+ -
Schoenfeld, Winston (11)	+ -
Vanstryland, Eric (10)	+ -
Abouraddy, Ayman (9)	+ -
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