Current Search: symmetry (x)


Title

Paritytime and supersymmetry in optics.

Creator

Miri, Mohammad, Christodoulides, Demetrios, Abouraddy, Ayman, Likamwa, Patrick, Choudhury, Sudipto, University of Central Florida

Abstract / Description

Symmetry plays a crucial role in exploring the laws of nature. By exploiting some of the underlying analogies between the mathematical formalism of quantum mechanics and that of electrodynamics, in this dissertation we show that optics can provide a fertile ground for studying, observing, and utilizing some of the peculiar symmetries that are currently out of reach in other areas of physics. In particular, in this work, we investigate two important classes of symmetries, paritytime symmetry ...
Show moreSymmetry plays a crucial role in exploring the laws of nature. By exploiting some of the underlying analogies between the mathematical formalism of quantum mechanics and that of electrodynamics, in this dissertation we show that optics can provide a fertile ground for studying, observing, and utilizing some of the peculiar symmetries that are currently out of reach in other areas of physics. In particular, in this work, we investigate two important classes of symmetries, paritytime symmetry (PT) and supersymmetry (SUSY), within the context of classical optics. The presence of PT symmetry can lead to entirely real spectra in nonHermitian systems. In optics, PTsymmetric structures involving balanced regions of gain and loss exhibit intriguing properties which are otherwise unattainable in traditional Hermitian systems. We show that selective PT symmetry breaking offers a new method for achieving single mode operation in laser cavities. Other interesting phenomena also arise in connection with PT periodic structures. Along these lines, we introduce a new class of optical lattices, the so called mesh lattices. Such arrays provide an ideal platform for observing a range of PTrelated phenomena. We show that defect sates and solitons exist in such periodic environments exhibiting unusual behavior. We also investigate the scattering properties of PTsymmetric particles and we show that such structures can deflect light in a controllable manner. In the second part of this dissertation, we introduce the concept of supersymmetric optics. In this regard, we show that any optical structure can be paired with a superpartner with similar guided wave and scattering properties. As a result, the guided mode spectra of these optical waveguide systems can be judiciously engineered so as to realize new families of mode filters and mode division multiplexers and demultiplexers. We also present the first experimental demonstration of light dynamics in SUSY ladders of photonic lattices. In addition a new type of transformation optics based on supersymmetry is also explored. Finally, using the SUSY formalism in nonHermitian settings, we identify more general families of complex optical potentials with real spectra.
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Date Issued

2014

Identifier

CFE0005844, ucf:50915

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFE0005844


Title

ATTACKS ON DIFFICULT INSTANCES OF GRAPH ISOMORPHISM: SEQUENTIAL AND PARALLEL ALGORITHMS.

Creator

Tener, Greg, Deo, Narsingh, University of Central Florida

Abstract / Description

The graph isomorphism problem has received a great deal of attention on both theoretical and practical fronts. However, a polynomial algorithm for the problem has yet to be found. Even so, the best of the existing algorithms perform well in practice; so well that it is challenging to find hard instances for them. The most efficient algorithms, for determining if a pair of graphs are isomorphic, are based on the individualizationrefinement paradigm, pioneered by Brendan McKay in 1981 with his...
Show moreThe graph isomorphism problem has received a great deal of attention on both theoretical and practical fronts. However, a polynomial algorithm for the problem has yet to be found. Even so, the best of the existing algorithms perform well in practice; so well that it is challenging to find hard instances for them. The most efficient algorithms, for determining if a pair of graphs are isomorphic, are based on the individualizationrefinement paradigm, pioneered by Brendan McKay in 1981 with his algorithm nauty. Nauty and various improved descendants of nauty, such as bliss and saucy, solve the graph isomorphism problem by determining a canonical representative for each of the graphs. The graphs are isomorphic if and only if their canonical representatives are identical. These algorithms also detect the symmetries in a graph which are used to speed up the search for the canonical representativean approach that performs well in practice. Yet, several families of graphs have been shown to exist which are hard for nautylike algorithms. This dissertation investigates why these graph families pose difficulty for individualizationrefinement algorithms and proposes several techniques for circumventing these limitations. The first technique we propose addresses a fundamental problem pointed out by Miyazaki in 1993. He constructed a family of colored graphs which require exponential time for nauty (and nauty's improved descendants). We analyze Miyazaki's construction to determine the source of difficulty and identify a solution. We modify the base individualizationrefinement algorithm by exploiting the symmetries discovered in a graph to guide the search for its canonical representative. This is accomplished with the help of a novel data structure called a guide tree. As a consequence, colored Miyazaki graphs are processed in polynomial timethus obviating the only known exponential upperbound on individualizationrefinement algorithms (which has stood for the last 16 years). The preceding technique can only help if a graph has enough symmetry to exploit. It cannot be used for another family of hard graphs that have a high degree of regularity, but possess few actual symmetries. To handle these instances, we introduce an adaptive refinement method which utilizes the guidetree data structure of the preceding technique to use a stronger vertexinvariant, but only when needed. We show that adaptive refinement is very effective, and it can result in dramatic speedups. We then present a third technique ideally suited for large graphs with a preponderance of sparse symmetries. A method was devised by Darga et al. for dealing with these large and highly symmetric graphs, which can reduce runtime by an order of magnitude. We explain the method and show how to incorporate it into our algorithm. Finally, we develop and implement a parallel algorithm for detecting the symmetries in, and finding a canonical representative of a graph. Our novel parallel algorithm divides the search for the symmetries and canonical representative among each processor, allowing for a high degree of scalability. The parallel algorithm is benchmarked on the hardest problem instances, and shown to be effective in subdividing the search space.
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Date Issued

2009

Identifier

CFE0002894, ucf:48018

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFE0002894


Title

Experiments in Graphene and Plasmonics.

Creator

Smith, Christian, Ishigami, Masa, Peale, Robert, Mucciolo, Eduardo, Chanda, Debashis, University of Central Florida

Abstract / Description

Graphene nanoribbons, graphene based optical sensors, and grating based plasmonics are explored experimentally. Graphene nanoribbons exhibit highly insulating states that may allow for graphene based digital applications. We investigate the sensitivity of these states to local charged impurities in ultra high vacuum. We look into the possibility of isolating twodimensional films of HBN and BSCCO, and test for any interesting phenomena. We also assess graphene's applicability for optical...
Show moreGraphene nanoribbons, graphene based optical sensors, and grating based plasmonics are explored experimentally. Graphene nanoribbons exhibit highly insulating states that may allow for graphene based digital applications. We investigate the sensitivity of these states to local charged impurities in ultra high vacuum. We look into the possibility of isolating twodimensional films of HBN and BSCCO, and test for any interesting phenomena. We also assess graphene's applicability for optical sensing by implementing a new style of spectral detector. Utilizing surface plasmon excitations nearby a graphene fieldeffect transistor we are able to produce a detector with wavelength sensitivity and selectivity in the visible range. Finally, we study another plasmonic phenomenon, and observe the resonant enhancement of diffraction into a symmetryprohibited order in silver gratings.
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Date Issued

2014

Identifier

CFE0005887, ucf:50874

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFE0005887


Title

Optical Parity Time Metasurface Structures.

Creator

El Halawany, Ahmed, Christodoulides, Demetrios, Rahman, Talat, Peale, Robert, Likamwa, Patrick, University of Central Florida

Abstract / Description

In the last few years, optics has witnessed the emergence of two fields namely metasurfaces and paritytime (PT) symmetry. Optical metasurfaces are engineered structures that provide unique responses to electromagnetic waves, absent in natural materials. Optical metasurfaces are known for their reduced dimensionality i.e. subwavelength and consequently lower losses are anticipated. The other paradigm is the PT symmetric materials, also known as photonic synthetic matter. PT symmetry has...
Show moreIn the last few years, optics has witnessed the emergence of two fields namely metasurfaces and paritytime (PT) symmetry. Optical metasurfaces are engineered structures that provide unique responses to electromagnetic waves, absent in natural materials. Optical metasurfaces are known for their reduced dimensionality i.e. subwavelength and consequently lower losses are anticipated. The other paradigm is the PT symmetric materials, also known as photonic synthetic matter. PT symmetry has emerged from quantum mechanics when a new class of nonHermitian Hamiltonian quantum systems was highlighted to have real eigenvalues, hence eradicating Hermiticity of the Hamiltonian as an essential condition to the existence of real eigenvalues.The first half of the thesis is focused on the experimental and numerical realization of PT symmetric metasurfaces. A systematic methodology is developed to implement this class of metasurfaces in both onedimensional and twodimensional geometries. In two dimensional systems, PT symmetry can be established by employing either Hlike diffractive elements or diatomic oblique Bravais lattices. It is shown that the passive PT symmetric metasurfaces can be utilized to appropriately engineer the resulting farfield characteristics. Such PTsymmetric structures are capable of eliminating diffraction orders in specific directions, while maintaining or even enhancing the remaining orders. Later, it is shown a first ever attempt of PT metasurface fabricated on a flexible polymer (polyimide) substrate. The studied PT metasurface exhibits the ability to direct light, i.e. Poynting vector in a desired direction. Herein, the light scattered from the fabricated device in the undesired direction is attenuated by at least an order of magnitude. The proposed PT symmetric metasurface is essentially diatomic Honeycomb Bravais lattice, where both the passive and lossy elements exist side by side on each site separated by 50 nm. The unidirectionality of the studied metasurface is not limited to a single wavelength, on the contrary, it is observed to be effective on the entire visible band (400 () 600 nm). The PT symmetric meatsurface is also fabricated on a high strength substrate; sapphire (Al2O3). An excellent agreement between the experimental and numerical (COMSOL) results is found for both substrates. Customized modifications to the current design can open avenues to study the unidirectionality of metasurfaces to different optical bands, for example IR.The second part of the thesis deals with the theoretical modeling of the dynamics of an electron that gets trapped by means of decoherence and quantum interference in the central quantum dot (QD) of a semiconductor nanoring (NR) made of five QDs, between 100 and 300 K. The electron's dynamics is described by a master equation with a Hamiltonian based on the tightbinding model, taking into account electron()LO phonon interaction. Based on this configuration, the probability to trap an electron with no decoherence is almost 27%. In contrast, the probability to trap an electron with decoherence is 70% at 100 K, 63% at 200 K and 58% at 300 K. Our model provides a novel method of trapping an electron at room temperature.This setup is then used to propose a theoretical model for an electrically driven single photon source operating at high temperatures. It is shown that the decoherence, which is usually the main obstacle for operating single photon sources at high temperatures, ensures an efficient operation of the presented electrically driven single photon source at high temperatures. The singlephoton source is driven by a single electron source attached to a heterostructure semiconductor nanoring. The electron's dynamics in the nanoring and the subsequent recombination with the hole is described by the generalized master equation with a Hamiltonian based on tightbinding model, taking into account the electronLO phonon interaction. As a result of decoherence, an almost 100% single photon emission with a strong antibunching behavior i.e. g(2)(0) (<)(<) 1 at high temperature up to 300 K is achieved.
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Date Issued

2016

Identifier

CFE0006454, ucf:51421

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFE0006454


Title

NonHermitian Optics.

Creator

Ulhassan, Absar, Christodoulides, Demetrios, Khajavikhan, Mercedeh, Likamwa, Patrick, Kaup, David, University of Central Florida

Abstract / Description

From the viewpoint of quantum mechanics, a system must always be Hermitian since all its corresponding eigenvalues must be real. In contrast, the eigenvalues of open systemsunrestrained because of either decay or amplificationcan be in general complex. Not so long ago, a certain class of nonHermitian Hamiltonians was discovered that could have a completely real eigenvalue spectrum. This special class of Hamiltonians was found to respect the property of commutation with the paritytime (PT)...
Show moreFrom the viewpoint of quantum mechanics, a system must always be Hermitian since all its corresponding eigenvalues must be real. In contrast, the eigenvalues of open systemsunrestrained because of either decay or amplificationcan be in general complex. Not so long ago, a certain class of nonHermitian Hamiltonians was discovered that could have a completely real eigenvalue spectrum. This special class of Hamiltonians was found to respect the property of commutation with the paritytime (PT) operator. Translated into optics, this implies a balance between regions exhibiting gain and loss. Traditionally, loss has been perceived as a foe in optics and something that needs to be avoided at all costs. As we will show, when used in conjunction with gain, the presence of loss can lead to a host of counterintuitive outcomes in such nonHermitian configurations that would have been otherwise unattainable in standard arrangements. We will study PT symmetric phase transitions in various optical settings that include semiconductor microrings and coupled fiber cavities, and show how they can allow modeselectivity in lasers. One of the key outcomes of this effort was the realization of higher order degeneracies in a threecavity laser configuration that can exhibit ordersofmagnitude larger sensitivity to external perturbations. We will also consider systems that display nonlinear effects such as gain saturation, thus allowing novel phase transitions. Some interesting properties associated with degeneracies in nonHermitian settings will be investigated as well. Such degeneracies, called exceptional points (EPs), are much more drastic compared to standard degeneracies of eigenvalues because the corresponding eigenvectors also coalesce, which in turn reduces the dimensionality of the phase space. We will show that dynamic parameter contours enclosing or close to EPs can lead to a robust chiral mode conversion process () something that can be potentially used to realize omnipolarizing optical devices.
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Date Issued

2018

Identifier

CFE0007259, ucf:52182

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFE0007259


Title

Analysis and Design of NonHermitian 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 nonHermitian 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 nonHermitian arrangements exhibiting novel nontrivial 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 fiberbased 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 nonzero transmission. In other words, at Poynting's threshold, the cavity becomes a 'transparent perfect mirror'. We have realized this effect in an onchip active waveguide device and in an opticalfiberbased system. Third, we have examined a paritytime (PT) symmetric fiberbased cavity consisting of two coupled subcavities, one of which contains gain and the other loss. In contrast to all previous onchip PTsymmetric microdevices, 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., lossinduced 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 (erbiumdoped) 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

An Examination of Domestic Violence Perpetration: A Further Look into the Gender Symmetry Debate.

Creator

Parra, Michelle, Reckdenwald, Amy, Gay, David, HuffCorzine, Lin, University of Central Florida

Abstract / Description

The influences of certain social changes and social movements, such as the feminist movement, in society introduced a violence gendered stereotype model that promoted the social idea that males are more violent than females. From the limited research, it appears that domestic violence perpetration among women differs from male domestic violence perpetration; however, research has not clarified the extent of female domestic violence perpetration and the severity of their abusive behaviors. The...
Show moreThe influences of certain social changes and social movements, such as the feminist movement, in society introduced a violence gendered stereotype model that promoted the social idea that males are more violent than females. From the limited research, it appears that domestic violence perpetration among women differs from male domestic violence perpetration; however, research has not clarified the extent of female domestic violence perpetration and the severity of their abusive behaviors. The current research examines genderspecific intimate partner violence perpetration to determine whether attitudes toward social gender role expectations, income contribution and production, and division of labor in the household can explain marital violence using secondary data collected from the National Survey of Families and Households. Findings indicate that significant differences were not found for perpetration of physical violence and attitudes about division of labor among women and men, but there were significant differences for men and women when taking into consideration their attitudes about income contribution, income production, and gender roles.
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Date Issued

2016

Identifier

CFE0006372, ucf:51503

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFE0006372


Title

NonHermitian and SpaceTime Mode Management.

Creator

Nye, Nicholas, Christodoulides, Demetrios, Khajavikhan, Mercedeh, Abouraddy, Ayman, Kaup, David, University of Central Florida

Abstract / Description

In the last few years, optics has witnessed the emergence of two fields namely metasurfaces and paritytime (PT) symmetry. Optical metasurfaces are engineered structures that provide unique responses to electromagnetic waves, absent in natural materials. On the other hand, PT symmetry has emerged from quantum mechanics, when a new class of nonHermitian Hamiltonian quantum systems was shown to have real eigenvalues. In this work, we demonstrate how PTsymmetric diffractive structures are...
Show moreIn the last few years, optics has witnessed the emergence of two fields namely metasurfaces and paritytime (PT) symmetry. Optical metasurfaces are engineered structures that provide unique responses to electromagnetic waves, absent in natural materials. On the other hand, PT symmetry has emerged from quantum mechanics, when a new class of nonHermitian Hamiltonian quantum systems was shown to have real eigenvalues. In this work, we demonstrate how PTsymmetric diffractive structures are capable of eliminating diffraction orders in specific directions, while maintaining/enhancing the remaining orders. In the second part of this work, we emphasize on supersymmetry (SUSY) and its applications in optics. Even though the full ramification of SUSY in highenergy physics is still a matter of debate that awaits experimental validation, supersymmetric techniques have already found their way into lowenergy physics. In this work, we apply certain isospectral techniques in order to achieve single mode lasing in multielement waveguide systems, where multimode chaotic emission is expected. In the third part of this dissertation, we emphasize on dynamically reconfigurable nanoparticle platforms. By exploiting the dielectrophoresis effect, we demonstrate how controllable lasing can be achieved in random photonic arrangements. Although this work focuses on the case of controlling random lasers, we expect that the proposed nanoparticle architecture can incorporate heterogeneous materials of a wide range of optical functionalities, including gain, scattering, plasmonic resonance, and nonlinearity. In the last part of the dissertation, we demonstrate the capability of synthesizing spacetime (ST) wave packets, based on new propagationinvariant elementary solutions of the wave equation identified through a complexification of the spatial and temporal degrees of freedom. By establishing the connection between ST propagationinvariant pulses and tiltedpulsefront pulses, a path is opened to exploiting the unique attributes of such wave packets both in nonlinear and quantum optics.
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Date Issued

2019

Identifier

CFE0007896, ucf:52780

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFE0007896


Title

EXPERIMENTAL AND THEORETICAL STUDY OF THE OPTICAL PROPERTIES OF SEMICONDUCTOR QUANTUM DOTS.

Creator

Nootz, Gero, Cuenya , Beatriz, University of Central Florida

Abstract / Description

The aim of this dissertation is to gain a better understanding of the unique electronic structure of lead salt quantum dots (QDs) and its influences on the nonlinear optical (NLO) properties as well as the time dynamics of the photogenerated charge carriers. A variety of optical techniques such as Zscan, twophoton excited fluorescence and timeresolved pump probe spectroscopy are used to measure these properties. The onephoton as well as the degenerate and nondegenerate twophoton...
Show moreThe aim of this dissertation is to gain a better understanding of the unique electronic structure of lead salt quantum dots (QDs) and its influences on the nonlinear optical (NLO) properties as well as the time dynamics of the photogenerated charge carriers. A variety of optical techniques such as Zscan, twophoton excited fluorescence and timeresolved pump probe spectroscopy are used to measure these properties. The onephoton as well as the degenerate and nondegenerate twophoton absorption (2PA) spectra are measured and the electronic wave functions from a fourband envelope function formalism are used to model the results. We observe local maxima in the 2PA spectra for QD samples of many different sizes at energies where only 1PA is predicted by the model. This is similar to the previously measured transitions in the 1PA spectra which are not predicted by the model but accrue at the energies of the twophoton allowed transitions. Most importantly we observe 2PA peaks for all samples at the energy of the first onephoton allowed transition. This result can only be understood in terms of symmetry breaking and therefore is strong evidence that other transitions, not predicted by the model if the selection rules are left intact, also have the origin in the lifted spatial symmetry of the wave functions. On the other hand, the uniquely symmetric eigenenergies of these quantumconfined energy states in the conduction and valance bands explain the observed trend toward larger twophoton crosssections as the quantum confinement is increased in smaller QDs. Moreover, this unique feature is shown to reduce the possible relaxation channels for photoexcited carriers, which is confirmed experimentally by the reduced carrier relaxation rate as compared to CdSe QDs which lack this symmetry. Carrier multiplication (CM), a process in which several electrons are excited by the absorption of a single photon is studied in PbS QDs. We show that for PbS QDs with radius smaller than 2.5 nm the parameters of CM get very close to the theoretical optimum. Nextgeneration solar cells operating under these ideal conditions could potentially have conversion efficiency of up to 42%. This compares favorably to the 30% efficiency limit of a single junction silicon solar cell.
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Date Issued

2010

Identifier

CFE0003396, ucf:48413

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFE0003396


Title

Novel Photonic Resonance Arrangements Using NonHermitian Exceptional Points.

Creator

Hodaeiesfahani, Seyedhossein, Khajavikhan, Mercedeh, Christodoulides, Demetrios, Likamwa, Patrick, Abdolvand, Reza, University of Central Florida

Abstract / Description

In recent years, nonHermitian degeneracies also known as exceptional points (EPs) have emerged as a new paradigm for engineering the response of optical systems. EPs can appear in a wide class of open nonHermitian configurations. Among different types of nonconservative photonic systems, paritytime (PT) symmetric arrangements are of particular interest since they provide an excellent platform to explore the physics of exceptional points. In this work, the intriguing properties of...
Show moreIn recent years, nonHermitian degeneracies also known as exceptional points (EPs) have emerged as a new paradigm for engineering the response of optical systems. EPs can appear in a wide class of open nonHermitian configurations. Among different types of nonconservative photonic systems, paritytime (PT) symmetric arrangements are of particular interest since they provide an excellent platform to explore the physics of exceptional points. In this work, the intriguing properties of exceptional points are utilized to address two of the long standing challenges in the field of integrated photonics enforcing single mode lasing in intrinsically multimode cavities and enhancing the sensitivity of microresonators.In the first part of this work, I will describe how stable single mode lasing can be readily achieved in longitudinally and transversely multimoded microring cavities through the systematic utilization of abrupt phase transitions at exceptional points. This technique will be first demonstrated in a paritytime laser that is comprised of a gain cavity coupled to an identical but lossy counterpart. A detailed study of the behavior of this system around the exceptional point will be presented. Furthermore, we report the first experimental realization of a dark state laser in which by strategically designing the spectral locations of exceptional points, widely tunable singlemode lasing can be attained even at high pump levels. Despite the presence of loss in such open laser systems, the slope efficiency remains virtually intact. Our results demonstrate the potential of exceptional points as a versatile design tool for mode management in onchip laser configurations.In the second part of my dissertation, I will show how the exceptional points and their underlying degeneracies can be used to significantly boost the intrinsic sensitivity of microcavities. I will demonstrate the enhanced sensitivity in a binary PTsymmetric coupled cavity arrangement that is biased at an exceptional point. Then I will report the first observation of higherorder exceptional points in a ternary paritytime symmetric microring laser system with a judiciously tailored gainloss distribution. The enhanced response associated with this ternary system follows a cubic root dependence on externally introduced perturbation, which can in turn be detected in the spectral domain. Using such arrangements, more than one order of magnitude enhancement in the sensitivity is observed experimentally. These results can pave the way towards improving the performance of current onchip microcavity sensors.
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Date Issued

2017

Identifier

CFE0006947, ucf:51627

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFE0006947


Title

PERCEPTION OF CUTENESS AND BEAUTY.

Creator

Jones, Danielle, Poindexter, Carla, University of Central Florida

Abstract / Description

Upbringing and psychological makeup inspire individual norms for beauty and cuteness. The mannerist approach in my work is a product of the figural liberties found in cartooning, illustration and art history. By altering facial and bodily features, I relate the proportions of an infant to cuteness and innocence. However, I tailor the photographs to empower the subjects all the while mirroring trends in contemporary pop culture. I'm interested in themes of everyday life, vitality and...
Show moreUpbringing and psychological makeup inspire individual norms for beauty and cuteness. The mannerist approach in my work is a product of the figural liberties found in cartooning, illustration and art history. By altering facial and bodily features, I relate the proportions of an infant to cuteness and innocence. However, I tailor the photographs to empower the subjects all the while mirroring trends in contemporary pop culture. I'm interested in themes of everyday life, vitality and emotion placed in obscure, imaginary or exaggerated venues. I fictionalize subjects of my reality to compel viewers to identify with and fancy emotions, circumstances, moods and relationships. The intent is to amplify, yet be truer to their existence and idiosyncrasies through figural adaptations.
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Date Issued

2009

Identifier

CFE0002538, ucf:47637

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFE0002538