在適當的條件下，正向入射激光束令GaAs量子阱微腔產生方向的不穩定性，並生成橫向光學圖案。方向不穩定性的形成是由於極化子，即光子及量子阱激子的強非線性耦合的本徵態，在微腔內散射的結果。電腦模擬顯示，通過一個非常弱的控制激光束，橫向光學圖案可以從一個方向切換到另一個。它可以作為一個全光學開關，而全光開關可有效地改善計算機的性能。 / 本論文先介紹GaAs量子阱微腔的理論及其數值模擬，以顯示GaAs量子阱微腔能夠產生光學圖案和全光學開關。然而，透過複雜的模擬數據去理解其規律及原理實在太困難。為此，我們發展一個低維的群種競爭模型，以理解這些現象。 / 為了分析群種競爭模型，我們應用了一些數學工具，如Gröbner bases 和廣義判式，以減少計算模型的相圖所需的電腦負荷。此外，我們也利用了突變理論來分類和解釋所有相圖中的相界。這個人口競爭模型使我們對不同物理系統中的圖案生成現象有一個全面的定性理解。 / 在本論文的最後一部分，我們研究量子阱雙微腔，即兩個耦合的微腔，而每個微腔中間也有一個量子阱。透過傳輸矩陣的方法，我們獲得了雙微腔的色散關係，並與實驗結果作比較。我們預期沿著這個研究方向在未來能夠加快實現全光開關。 / Under favorable conditions, laser beams incident normally to a GaAs quantumwell microcavity develop directional instabilities and generate transverse patterns in the far field. The directional instabilities are driven by scattering among polaritons inside the microcavity, where the polaritons are the eigenstates of strong linear coupling between the cavity photons and the excitons inside the quantum-well. It has been predicted that the transverse pattern can be switched from one to another by the use of a very weak control beam. It can serve as an all-optical switching, which can potentially be used to improve computers’ performance. / In this thesis, the theory of the GaAs quantum-well microcavity is first introduced and numerical results showing the formation of patterns and the all-optical switching scheme are presented. However, understanding the patterns and their dynamics through numerical simulations turns out to be very complicated. To this end, we derive a low-dimensional population-competition model for the interpretation of these behaviors. / To facilitate the analysis the population-competition model, we apply mathematical tools such as the Gröbner basis and the generalized discriminant to reduce the computational load in finding the ‘phase diagrams’ of the populationcompetition model. Besides, we also make use of the catastrophe theory to classify and explain all the phase boundaries in the phase diagrams. This population-competition model enables us to acquire an overall qualitative picture of pattern formation in various physical systems. / In the last part of this thesis, we use the transfer-matrix method to study the polariton spectrum of a quantum-well double-microcavity, which is two coupled optical cavities each containing a quantum well, and compare the spectrum with the experimental results. We expect our efforts along this direction could expedite realization of all-optical switching in the future. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Tse, Yuen Chi = 分析橫向光學圖案的低維群種競爭模型 / 謝沅志. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 112-119). / Abstracts also in Chinese. / Tse, Yuen Chi = Fen xi heng xiang guang xue tu an de di wei qun zhong jing zheng mo xing / Xie Yuanzhi. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Optical computation and all-optical switching --- p.3 / Chapter 1.2 --- Nonlinear optics and low-intensity ultra-fast all-optical switching of transverse optical pattern --- p.4 / Chapter 1.3 --- Pattern formation and amplitude equation formalism --- p.6 / Chapter 1.4 --- Semiconductor quantum-well double-microcavity and transfermatrix method --- p.9 / Chapter 2 --- Semiconductor quantum-well microcavity --- p.10 / Chapter 2.1 --- Physical configuration and theroy --- p.10 / Chapter 2.2 --- Simplified models --- p.19 / Chapter 2.3 --- Directional instability and the effect of anisotropy in model PCO-Q --- p.25 / Chapter 2.4 --- Effect of control beam and all-optical switching in PCO-Q --- p.30 / Chapter 2.5 --- Simulation results of model PCO-L, a model without quadratic dependence --- p.33 / Chapter 3 --- Population-competition model --- p.37 / Chapter 3.1 --- Derivation of PC model --- p.37 / Chapter 3.1.1 --- Approximation from the simulation results --- p.38 / Chapter 3.1.2 --- Adiabatic approximation for the field equations --- p.39 / Chapter 3.1.3 --- Revised dynamical equations --- p.40 / Chapter 3.1.4 --- Taylor expansion approximation about phase locking --- p.42 / Chapter 3.1.5 --- Comparison with the simulation results --- p.45 / Chapter 3.1.6 --- Modelling of the control beam --- p.47 / Chapter 3.1.7 --- Reduction in the number of parameters --- p.47 / Chapter 3.2 --- Physical meaning of the simplified PC model --- p.49 / Chapter 3.3 --- Comparison with amplitude equations formalism and others competition models --- p.49 / Chapter 4 --- Mathematical tools --- p.52 / Chapter 4.1 --- Steady states and linear stability analysis --- p.52 / Chapter 4.2 --- Gröbner basis --- p.54 / Chapter 4.3 --- Generalized discriminant --- p.55 / Chapter 4.4 --- Algorithm for conditions for qualitative changes --- p.56 / Chapter 4.5 --- Reduction in computational power --- p.57 / Chapter 4.6 --- Elementary catastrophe theory --- p.58 / Chapter 5 --- Population-competition model analysis --- p.66 / Chapter 5.1 --- Symmetric model L without source term --- p.67 / Chapter 5.2 --- Symmetric model Q without source term --- p.70 / Chapter 5.3 --- Asymmetric model L and Q without source term --- p.74 / Chapter 5.4 --- Symmetric models L and Q with control beam S₂ --- p.80 / Chapter 5.5 --- Asymmetric Model L and Q with control beam S₂ --- p.81 / Chapter 6 --- Semiconductor quantum-well double-microcavity --- p.91 / Chapter 6.1 --- Motivation --- p.91 / Chapter 6.2 --- Transfer-matrix method inside dielectrics --- p.94 / Chapter 6.3 --- Transfer-matrix method across QW --- p.97 / Chapter 6.4 --- Analysis of the QWDM through transfer-matrix method --- p.98 / Chapter 7 --- Conclusion and Outlook --- p.105 / Chapter 7.1 --- Conclusion --- p.105 / Chapter 7.2 --- Outlook --- p.107 / Chapter 7.2.1 --- Extension of the PC model --- p.107 / Chapter 7.2.2 --- Extension of the transfer-matrix method to nonlinear analysis --- p.109 / Bibliography --- p.112 / Chapter A --- Dispersion relations inside QWM --- p.120 / Chapter B --- Analysis on the steady states with and without off-axis instability --- p.122 / Chapter B.1 --- Steady states of E₀ and p₀ --- p.122 / Chapter B.2 --- Analysis on the steady states without off-axis instability --- p.123 / Chapter B.3 --- The effects of instability on E₀ and p₀ --- p.124 / Chapter C --- Analytical derivation of the phase diagram asymmetry versus quadratic terms (δβ1 vs γ) without control beam (S₂ = 0) --- p.127 / Chapter D --- Verification of the elliptic umbilic (D₋₄) singularity --- p.129

No description available.

Thesis (Ph. D.)--Michigan State University. Dept. of Physics and Astronomy, 2006. / Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references (p. 73-76). Also issued in print.

A caracterização das propriedades ópticas de moléculas de DNA, tais como a absorção e a fluorescência por excitação, são importantes para a determinação de parâmetros usados no desenvolvimento de biossensores fotônicos. O estudo da absorção óptica do DNA, obtido por diferentes métodos tem se mostrado muito eficiente na determinação do grau de pureza do material genético obtido por amplificação, ou extração e purificação do DNA total. Por outro lado, a fluorescência por excitação a partir de um marcador cromóforo é uma técnica importante em processos de quantificação de massa, em técnicas tais como a eletroforese em gel de agarose. Devido à baixa fluorescência de moléculas de DNA na região visível do espectro, entre 500-600nm, utiliza-se destes marcadores que se ligam à molécula e que são opticamente ativos nesta região para detecção de sua emissão de fluorescência. Neste trabalho foi realizado um estudo da fluorescência do DNA, obtido a partir de uma amplificação por transcriptase reversa do RNA (RT-PCR), na região de 400nm a 600nm, sem adição de marcador e utilizando excitação por um e dois fótons (405nm e 800nm) através da técnica de microscopia confocal. As amostras contendo solução de dsDNA (237ng/μL) foram depositadas sobre um filme de prata de 200nm de espessura que também é crescido previamente sobre um substrato de vidro. Sobre o filme metálico é fabricado nanoestruturas metálicas por de litografia por feixe de íons com um microscópio de duplo feixe FEI Quanta 3D 200i. As nanoestruturas são formadas por arranjos concêntricos de anéis com diâmetros de até 20 μm, largura 50nm e separados por 400nm. Quando a excitação do material genético ocorre sobre a nanoestrtutura o laser gera na nanoestrutura plasmon-polaritons de superfície (SPP) que interagem com as moléculas de dsDNA na solução. Observa-se que nas regiões onde as nanoestruturas são fabricadas que a intensidade de fluorescência da macromolécula é muito maior do que a obtida fora da estrutura e sobre o filme metálico. Os efeitos da interação entre SPPs e as moléculas aumentam a atividade óptica (taxa de emissão) e podem servir como base para a fabricação de sensores fotônicos ultrasensíveis. Concluindo, os efeitos dos campos plasmônicos sobre o fluoróforo são significativos e foram observados pela diminuição do tempo de vida das moléculas e o aumento da sua fluorescência. / The characterization of the optical properties of DNA molecules, such as absorption and excitation fluorescence, is important to the determination of the parameters used for the preparation of photonic biosensors. The study of optical absorption of DNA, obtained through different methods, currently has a high sensitivity to determine the degree of purity of the genetic material obtained by amplification, extraction and purification of the total DNA. On the other hand, excitation fluorescence using a marker is an important technique in mass quantification processes together with techniques such as agarose gel electrophoresis. Because of low fluorescence of DNA molecules, in the visible region of the spectrum, between 500-600nm, the use of labels that bind to the molecule are critically for the detection of their fluorescence emission. In this work we studied the DNA fluorescence, obtained from a RNA reverse transcriptase (RT-PCR) amplification, in the region from 400nm to 600nm, without the addition of a marker as a fluorophore and using confocal microscopy with one and two photons (405nm and 800nm). The solutions of dsDNA (237ng/μL) were dropped on a silver film with 200nm tackiness deposited on a glass substrate. In the silver film nanostructures were fabricated ion beam lithography with FEI Quanta 3D 200i dual beam microscope. The nanostructures are formed by concentric arrangements of rings with diameters up to 20 μm, width 50nm and separated by 400nm. When the excitation of the genetic material occurs on a nanostructure an excited surface plasmon-polaritons (SPP) is responsible for the DNA excitation. It is observed in these regions an increase of the fluorescence intensity many times higher than one obtained out of the nanostructure on the silver film. The effects of the interaction between SPPs and molecules increase the optical activity of the molecule (emission rate) and can serve as the basis of photonic sensors. Concluding, the effects of the plasmon fields on the fluorophore are significant and were observed by decreasing the life time of the molecules and the increasing of their fluorescence.

A caracterização das propriedades ópticas de moléculas de DNA, tais como a absorção e a fluorescência por excitação, são importantes para a determinação de parâmetros usados no desenvolvimento de biossensores fotônicos. O estudo da absorção óptica do DNA, obtido por diferentes métodos tem se mostrado muito eficiente na determinação do grau de pureza do material genético obtido por amplificação, ou extração e purificação do DNA total. Por outro lado, a fluorescência por excitação a partir de um marcador cromóforo é uma técnica importante em processos de quantificação de massa, em técnicas tais como a eletroforese em gel de agarose. Devido à baixa fluorescência de moléculas de DNA na região visível do espectro, entre 500-600nm, utiliza-se destes marcadores que se ligam à molécula e que são opticamente ativos nesta região para detecção de sua emissão de fluorescência. Neste trabalho foi realizado um estudo da fluorescência do DNA, obtido a partir de uma amplificação por transcriptase reversa do RNA (RT-PCR), na região de 400nm a 600nm, sem adição de marcador e utilizando excitação por um e dois fótons (405nm e 800nm) através da técnica de microscopia confocal. As amostras contendo solução de dsDNA (237ng/μL) foram depositadas sobre um filme de prata de 200nm de espessura que também é crescido previamente sobre um substrato de vidro. Sobre o filme metálico é fabricado nanoestruturas metálicas por de litografia por feixe de íons com um microscópio de duplo feixe FEI Quanta 3D 200i. As nanoestruturas são formadas por arranjos concêntricos de anéis com diâmetros de até 20 μm, largura 50nm e separados por 400nm. Quando a excitação do material genético ocorre sobre a nanoestrtutura o laser gera na nanoestrutura plasmon-polaritons de superfície (SPP) que interagem com as moléculas de dsDNA na solução. Observa-se que nas regiões onde as nanoestruturas são fabricadas que a intensidade de fluorescência da macromolécula é muito maior do que a obtida fora da estrutura e sobre o filme metálico. Os efeitos da interação entre SPPs e as moléculas aumentam a atividade óptica (taxa de emissão) e podem servir como base para a fabricação de sensores fotônicos ultrasensíveis. Concluindo, os efeitos dos campos plasmônicos sobre o fluoróforo são significativos e foram observados pela diminuição do tempo de vida das moléculas e o aumento da sua fluorescência. / The characterization of the optical properties of DNA molecules, such as absorption and excitation fluorescence, is important to the determination of the parameters used for the preparation of photonic biosensors. The study of optical absorption of DNA, obtained through different methods, currently has a high sensitivity to determine the degree of purity of the genetic material obtained by amplification, extraction and purification of the total DNA. On the other hand, excitation fluorescence using a marker is an important technique in mass quantification processes together with techniques such as agarose gel electrophoresis. Because of low fluorescence of DNA molecules, in the visible region of the spectrum, between 500-600nm, the use of labels that bind to the molecule are critically for the detection of their fluorescence emission. In this work we studied the DNA fluorescence, obtained from a RNA reverse transcriptase (RT-PCR) amplification, in the region from 400nm to 600nm, without the addition of a marker as a fluorophore and using confocal microscopy with one and two photons (405nm and 800nm). The solutions of dsDNA (237ng/μL) were dropped on a silver film with 200nm tackiness deposited on a glass substrate. In the silver film nanostructures were fabricated ion beam lithography with FEI Quanta 3D 200i dual beam microscope. The nanostructures are formed by concentric arrangements of rings with diameters up to 20 μm, width 50nm and separated by 400nm. When the excitation of the genetic material occurs on a nanostructure an excited surface plasmon-polaritons (SPP) is responsible for the DNA excitation. It is observed in these regions an increase of the fluorescence intensity many times higher than one obtained out of the nanostructure on the silver film. The effects of the interaction between SPPs and molecules increase the optical activity of the molecule (emission rate) and can serve as the basis of photonic sensors. Concluding, the effects of the plasmon fields on the fluorophore are significant and were observed by decreasing the life time of the molecules and the increasing of their fluorescence.

The properties of surface plasmon polaritons which propagate in optically nonlinear or magnetic media are investigated. Expressions for the electromagnetic fields of a multilayer stack are derived by modification of the Fresnel reflection coefficients. Original research on prism-coupled, nonlinear, long-range surface plasmon polaritons, and on bound and prism-coupled, long-range surface magnetoplasmon polaritons in a transversely-applied magnetic field, is compared to previous research on single-interface plasmon polaritons. The reflectance from prism-coupled, nonlinear surface plasmons is analyzed using the infinite plane-wave approximation and a substrate nonlinearity which depends on the square of the transverse-electric field. Bistable switching requires incident intensities two orders of magnitude smaller for the long-range mode than for the single-interface mode. The regime in which the approximations are valid is shown to extend beyond that of first-order perturbation theory to guided waves that are very near cutoff. The sign and location of the nonlinearity become significant for these waves. For positive nonlinearities, nonlinear wave analysis indicates an additional branch of the reflected intensity curve, due to self-focussing of the guided wave. Positive and negative nonlinearities exhibit different switching intensities. The propagation constant of the long-range surface plasmon of a magnetic metal film is shifted by the application of a transverse magnetic field. The sign and magnitude of the shift are highly dependent on the metal thickness and the refractive indices of the bounding media. The shift is manifested experimentally as a resonant modulation of the reflectance from the prism-coupled surface plasmon due to changes in the angular position and width of the plasmon resonance. Experimental prism-coupling to the long-range surface magnetoplasmon in thin nickel films confirms the theoretical expectations for a wide variety of sample parameters. The phase of the magneto-optic coefficient is determined from the angular profile of the reflectance modulation. Although the shift of the propagation constant may be two orders of magnitude smaller for the long-range mode, the modulation signal is the same order of magnitude for long-range and single-interface magnetoplasmons.

近年來，表面等離子體因為可以在金屬表面激發極強的局部電磁場而受到廣泛的關注。它是光和物質之間的重要的聯繫。基於它在納米量級上操控和引導光子的能力，表面等離子體已廣泛應用于納米和生物光學之中，比如生物傳感器，表面增強拉曼散射，光鑷，發光二極管，太陽能電池和超材料等等。然而，儘管系統結構，材料特性，激發光波長和條件都會影響表面等離子體本身的特性以及它與材料之間的相互作用，這些外部條件的整體效果卻常常不為人所知。更重要的是，在表面等離子體和這些外部條件之間，似乎仍有未知的聯繫存在。比如，現在人們仍然不是很清楚激發表面等離子體的納米結構到底是怎樣控制它以及與它相關的特性的。 / 在這篇論文里，我們希望通過耦合模理論將這些外部條件和表面等離子體特性聯繫起來。耦合模理論提供了表面等離子體吸收和輻射壽命等內部參數以及它們與光相位，振幅，傳播方向的關係。因為這些外部條件和壽命參數，激發條件之間的聯繫廣為人知，我們因此就可以把這些外部條件和表面等離子體特性聯繫起來了。一旦獲得了這些壽命參數，我們亦可從另外一個角度研究表面等離子體的基本特性。比如，我們發現兩個簡併表面等離子體耦合除了形成超模式和次模式以外，它們的輻射壽命和吸收壽命都發生了改變。另外，我們在實空間和動量空間研究了表面等離子體衰變長度，群速度等其他內部參數，并發現它們和等離子體衰減及態密度有重要聯繫。我們還發現基於相位躍變的表面等離子體傳感器在臨界耦合時將獲得最優表現。最後，通過研究發光材料和表面等離子體之間的耦合效率，我們發現態密度在其中起了關鍵作用。 / Surface plasmons (SPs), which generate strong localized electromagnetic fields at metal surface, have been capturing worldwide attention recently because they establish an important link between light and matter. Due to their ability to route and manipulate photon at the nanoscale, SPs have been widely used in nano- and bio-photonics including biosensor, surface enhanced Raman scattering, optical tweezers, light emitting diodes, solar cell, and metamaterials, etc. However, although it is known that system geometry, material, wavelength, excitation condition are important in governing the behaviors of SPs as well as matter/SPPs interactions, how they work together in producing the final outcome is largely unknown. More importantly, there seems to be a "missing link" between these extrinsic parameters and the properties of SPs such that, for example, it is still not quite understood the exact roles of geometry play in controlling the SPs and their related properties. / In this thesis, we aim at bridging the link between extrinsic parameters and SPs properties based on temporal coupled-mode theory (CMT). CMT provides the knowledge of intrinsic parameters such as SPs radiative and absorption rates and their relationships with the phase, amplitude, and directionality of SPs. Because decay rates are strong function of system parameters, excitation condition, etc, connection between the extrinsic parameters and the SPs properties can now be established. With the decay rates and other accessories in hand, we study the fundamental of SPs from another perspective. For example, we examine how two degenerate SPs modes couple to yield a pair of dark and bright modes and find not only the radiation damping of SPs but also the absorption are modified. In addition, we study the decay length and the group velocity of SPs in real- and momentum- space to elucidate the interplay between the SPs losses and the wavevector-resolved projected density-of-optical-states (PDOS). We also explore the rate matching (i.e. critical coupling) for optimizing the phase-jump in SPs resonance sensing and achieve high figure of merit in sensing performance. Finally, the coupling between SPs and light emitters has been studied and it is found that their coupling rate is governed by PDOS. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Cao, Zhaolong = 表面等離子體激元在金屬納米洞陣列上的衰變研究及其應用 / 曹兆龍. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 142-149). / Abstracts also in Chinese. / Cao, Zhaolong = Biao mian deng li zi ti ji yuan zai jin shu na mi dong zhen lie shang de shuai bian yan jiu ji qi ying yong / Cao Zhaolong.

This thesis presents a study of Surface Plasmon Polaritons (SPPs) in hybrid metal-dielectric waveguides. The embedding of metal in nanostructured photonic components allows for manipulating and guiding light at the subwavelength scale. Such an extreme confinement enhances the nonlinear response of the dielectric medium, which is important for applications in optical processing of information, but is paid in terms of considerable ohmic loss in the metal. It is, however, possible to embed externally pumped active inclusions in the dielectric in order to compensate for the metal loss. A novel perturbative theory for Maxwell equations is introduced and applied to various nonlinear metal-dielectric structures, deriving the propagation equation for the optical field. The nonlinear dispersion law for amplified SPPs, filamentation and dissipative plasmon-soliton formation have been studied, revealing intrinsic core and tail instabilities that prevent solitons to propagate over long distances. Stable propagation of plasmon-solitons can be achieved in insulator-metal-insulator structures with active and passive interfaces. The active SPP is coupled with the passive SPP, which absorbs the perturbations destabilising the zero background of the soliton. Theoretical modelling of optical propagation in metal-dielectric stacks predicts a modified two-band structure, allowing for gap/discrete plasmon-soliton formation. Loss and nonlinear parameters in subwavelength nanowire waveguides are evaluated and compared to the results obtained by other research groups. In all calculations, particular attention is paid in considering boundary conditions accounting for loss and nonlinear corrections, which contribute to the propagation equation with a surface term that becomes significant in the subwavelength regime.

Typescript. Includes vita and abstract. Includes "Monte Carlo SPP Scattering Simulation Program" (leaves 107-123) Includes bibliographical references (leaves 124-129) Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

Photonic crystals are media with periodically varying optical properties. Photonic crystals enable exquisite control of light propagation in integrated optical circuits and also emulate advanced physical concepts. However, common photonic crystals directly pattern the optical medium and thus are unfit for in-operando on/off controls. In this dissertation, we introduced, fabricated, and studied the properties of graphene polaritonic crystals. Our polaritonic crystal system consists of a pristine sheet of graphene in a back-gated platform with nano-structured gate insulators. We employed scattering-type scanning near-field optical microscopy (s-SNOM) to study the novel properties of polaritons propagating in the polaritonic crystal. We demonstrated the formation of a polaritonic bandgap, variations of the polaritonic local density of states, and the emergence of polaritonic domain wall states. We also revealed the programmable control of the polariton propagation direction and reconstructed the polaritonic bandstructure from real-space polariton images. The exploration of topological polaritonic phenomena in the polaritonic crystal relies on the selective excitation of topologically non-trivial modes using a chiral polariton launcher. We searched for the design of an efficient chiral polariton launcher. Throughout the journey, we visualized the polaritonic vortex mode of hBN phonon-polaritons. We discovered that the optical spin angular momentum of hBN phonon-polaritons resembles nano-scale meron spin textures. The meron spin texture possesses a half-integer topological charge determined by the handedness of the incident beam. The polaritonic crystal platform studied in this dissertation sheds light on the exploration of topologically non-trivial polaritonic states, such as valley plasmons and topological edge states. In addition, our electrostatically-tunable polaritonic crystals are derived from standard metal oxide semiconductor field-effect transistor technology and pave a way for practical on-chip light manipulation.