There are two topics in this dissertation: one is to develop new phase reduction algorithms for test interferograms especially of large optics and the other one is to find more accurate analytical expression of surface deflection due to gravity when the mirror is supported in the axial direction. Two new algorithms for generating phase maps from interferograms are developed. Both methods are sensitive to small-scale as well as large-scale surface errors. The first method is designed to generate phase from an interferogram that is sampled and digitized only along fringe centers, as in the case of manual digitization. A new interpolation algorithm uses the digitized data more efficiently than the fitting of Zernike polynomials, so the new method can detect small-scale surface error better than Zernike polynomial fitting. The second algorithm developed here is an automatic phase reduction process which works on test interferograms recorded by CCD camera and transferred digitally to a personal computer through a frame grabber. The interferogram results from interference of the test wavefront with a tilted reference wave-front. Phase is generated by assuming it to be proportional to the intensity of the interferogram, apart from changes of sign and offset occurring every half fringe so as to make the phase increase monotoically. The error of the new algorithm is less than 1/20 waves in the wavefront, which can be reduced further by averaging several phase maps which are generated by interferograms with random phase shifts. The new algorithm is quick and involves no smoothing, so it can detect surface errors on large mirrors on a scale of several centimeters. A new model is developed to calculate analytically the surface deflection of a mirror supported axially on multiple points. It is based on thin plate theory, but considerations of thickness variation of a curved mirror, lightweight honeycomb structure and shear are included. These additions improve the accuracy of the calculated surface deflection, giving results close to those obtained from the accurate but computer intensive finite element model.

Wang Chengqing. / "November 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Yuen, Kin Pong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 93-95). / Yuen, Kin Pong. / Contents --- p.i / Abstract --- p.iv / Acknowledgement --- p.v / List of Figures --- p.vi / Chapter Chapter 1. --- Introduction --- p.1 / Chapter Chapter 2. --- Optically Bistable Behavior --- p.5 / Chapter 2.1 --- Bistable behavior of two component composites --- p.5 / Chapter 2.1.1 --- Formalism --- p.6 / Chapter 2.1.2 --- Results and Discussion --- p.7 / Chapter 2.1.3 --- Stability analysis --- p.9 / Chapter 2.2 --- Bistable behavior of three component composites: Nonlinear dielec- tric core embedded in a metallic shell --- p.11 / Chapter 2.2.1 --- Spectral representation of the local field --- p.11 / Chapter 2.2.2 --- The onset of bistable behavior --- p.20 / Chapter 2.2.3 --- The extinction coefficient and reflectance at normal incidence --- p.24 / Chapter 2.2.4 --- Discussion and Conclusion --- p.28 / Chapter 2.3 --- Bistable behavior of three component composites: Metallic core em- bedded in a nonlinear dielectric shell --- p.30 / Chapter 2.3.1 --- Linear response of spherical inclusions and concentric spheres --- p.31 / Chapter 2.3.2 --- Onset of bistable behavior --- p.35 / Chapter 2.3.3 --- Results and Discussion --- p.41 / Chapter 2.4 --- Possible development of the spectral representation --- p.44 / Chapter Chapter 3. --- Optical Repsonse of a Nonlinear Composite Film --- p.45 / Chapter 3.1 --- Enhanced nonlinear response of coated spheres --- p.46 / Chapter 3.2 --- Solution of nonlinear wave equation --- p.48 / Chapter 3.3 --- Results and Discussion --- p.49 / Chapter 3.4 --- Conclusion --- p.52 / Chapter 3.5 --- Transfer matrix formalism for transmittance: Possible control over the size of a photonic band gap --- p.52 / Chapter 3.5.1 --- Transfer matrix method --- p.54 / Chapter Chapter 4. --- Bounds and Estimates for Nonlinear Composites --- p.59 / Chapter 4.1 --- Linear response of spherical inclusions --- p.60 / Chapter 4.2 --- Strongly nonlinear response of spherical inclusions --- p.61 / Chapter 4.3 --- Linear response of concentric spheres --- p.64 / Chapter 4.4 --- Strongly nonlinear response of concentric spheres --- p.66 / Chapter 4.5 --- Some exactly solvable cases --- p.68 / Chapter 4.6 --- Concentric spheres with nonlinear shell embedded in a linear dielec- tric host --- p.71 / Chapter 4.7 --- Discussion and Conclusion --- p.73 / Chapter 4.8 --- Small contrast expansion --- p.75 / Chapter 4.9 --- Hashin-Shtrikman microgeometry --- p.78 / Chapter 4.10 --- Exact bounds for linear composites --- p.79 / Chapter 4.11 --- Variational approach for Hashin-Shtrikman microstructure --- p.82 / Chapter 4.12 --- Improved variational approach --- p.85 / Chapter 4.13 --- Discussion and Conclusion --- p.87 / Appendix A. Derivation of the Energy Functional --- p.88 / Chapter A.1 --- The energy functional --- p.88 / Chapter A.2 --- Effect of higher order terms to the energy functional --- p.91 / Bibliography --- p.93

No description available.

Law, Man Fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 84-86). / Text in English; abstract also in Chinese. / Law, Man Fai. / Contents --- p.i / Abstract --- p.iii / Acknowledgement --- p.iv / List of Figures --- p.v / List of Tables --- p.ix / Chapter Chapter 1. --- Introduction --- p.1 / Chapter Chapter 2. --- Spectral Representation of Composite Materials --- p.4 / Chapter 2.1 --- Spectral method --- p.6 / Chapter 2.2 --- General properties --- p.10 / Chapter 2.3 --- Duality --- p.12 / Chapter 2.4 --- Dilute limit --- p.13 / Chapter 2.5 --- Effective-medium approximation (EMA) --- p.15 / Chapter 2.6 --- Moment expansions --- p.16 / Chapter Chapter 3. --- Local Field Effect and Depolarization Factor --- p.19 / Chapter 3.1 --- Isotropic homogeneous media --- p.20 / Chapter 3.2 --- Linear anisotropic homogeneous media --- p.22 / Chapter 3.3 --- Inhomogeneous anisotropic media --- p.24 / Chapter Chapter 4. --- Simulation on Correlated Microstructures --- p.26 / Chapter 4.1 --- Solving the nonlinear impedance networks --- p.27 / Chapter 4.2 --- Models of correlated microstructure --- p.29 / Chapter 4.2.1 --- Two-site correlated microstruture --- p.29 / Chapter 4.2.2 --- Environment correlated microstructure --- p.38 / Chapter 4.3 --- Conclusions --- p.45 / Chapter Chapter 5. --- Simulation on Anisotropic Microstructure --- p.46 / Chapter 5.1 --- Solving anisotropic impedance networks --- p.50 / Chapter 5.2 --- Simulation and results --- p.50 / Chapter 5.2.1 --- Parallel response --- p.51 / Chapter 5.2.2 --- Perpendicular response --- p.57 / Chapter 5.2.3 --- Unpolarized response --- p.61 / Chapter 5.3 --- Conclusions --- p.65 / Chapter Chapter 6. --- Conclusions --- p.66 / Appendix A. Symbolic Simulation --- p.67 / Chapter A.1 --- Formalism --- p.67 / Chapter A.2 --- Scaling Properties --- p.69 / Chapter A.3 --- The simulation --- p.71 / Appendix B. Fluctuation of Local Field in Composite Materials --- p.74 / Chapter B.l --- Simulations and Results --- p.74 / Appendix C. Lattice Animals in Correlated Network --- p.82 / Bibliography --- p.84

表面等離子體激元和熒光分子之間的電磁相互作用已因廣泛應用於量子運算中的量子信息處理和分子生物技術的分子檢測而得到相當大的關注。雖然通過把熒光分子放置在電漿系統旁來改善熒光分子的發光度和方向性已被廣泛接受，但是了解表面等離子體激元和熒光材料之間的相互作用的物理亦是很重要的。 / 在這篇論文中，我們將研究在二維納米銀洞陣列上有機染料帶方向性的發光特性。通過量度在每個角度的反射和熒光發光光譜，我們可以繪製出二維納米銀洞陣列所產生的電磁共振模式的色散關係及熒光材料發光度與方向的關係。此外，在陣列上以不同方向行走的表面等離子體激元的衰變壽命亦被找出。我們亦將反射率和熒光發光光譜進行比較，從而發現熒光發光的加強跟表面等離子體激元的光譜位置、衰變後傳播的方向、它的衰變壽命和它的耦合效率有十分密切的關係。為了解背後的物理，我們建立了一個理論模型去區分能量從有機染料轉移到表面等離子體激元的過程與表面等離子體激元衰變過程對表面等離子體激元改變熒光材料發光度的影響。因此，我們可以對能量從有機染料轉移到表面等離子體激元的過程與方向的關係進行定量分析。最後，我們的研究結果與由有限差分時域模擬計算所得的結果吻合。結論得出在二維納米銀洞陣列上所實現的表面等離子體激元増加有機染料光提取效率與三維空間中方向的關係是源於電漿帶隙的產生所引致的態密度重整及分配。 / The electromagnetic interaction between surface plasmon polaritons (SPPs) and fluorescent molecules has been capturing considerable attention for a wide variety of applications ranging from quantum information processing in quantum computing to molecule detection in biotechnology. Although it is widely accepted that the light emission efficiency and directionality are improved by placing the fluorescent molecules in close proximity to a plasmonic system, the understanding of the physics on how SPPs interact with the fluorescent materials is of importance. / In this thesis, the directional emission properties of LDS organic dyes supported on two-dimensional Ag nanohole array is studied. Angle-resolved reflectivity and photoluminescence spectroscopy have been employed to map out the dispersion relations of electromagnetic resonance modes arising from the array and the dependence of plasmonic emission on emission angle. In addition, the decay lifetimes of SPP modes in different propagation directions in array have been determined. By comparing the reflectivity and photoluminescence mappings, we find that the emission enhancement is strongly correlated with the spectral and angular positions of SPP modes together with their lifetimes and coupling efficiencies. To understand the underlying physics, we have developed an analytical model to differentiate the surface plasmon mediated emission (SPME) into energy transfer from LDS to SPPs and the radiative decay of surface plasmons. As a result, the directional dependence of the energy transfer process can then be analyzed quantitatively. Finally, our results are compared with the finite-difference-time-domain simulations with good agreement. It is concluded that the directional dependence of the surface plasmon mediated emission is attributed to the redistribution of the density of states in the periodic nanohole array due to the opening of the plasmonic gaps. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chan, Kay Fung = 表面等離子體激元改變納米金屬洞陣列上發光材料的光提取效率 / 陳其鋒. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 115-123). / Abstracts also in Chinese. / Chan, Kay Fung = Biao mian deng li zi ti ji yuan gai bian na mi jin shu dong zhen lie shang fa guang cai liao de guang ti qu xiao lu / Chen Qifeng. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Surface plasmon polaritons (SPPs) and surface plasmon mediated emission (SPME) --- p.2 / Chapter 1.2 --- Directional surface plasmon mediated emission (SPME) on metallic nanohole array --- p.5 / Chapter 1.3 --- Our analytical model of surface plasmon mediated emission --- p.8 / Chapter 1.3.1 --- Formalism of rate equations --- p.8 / Chapter 1.3.2 --- Determination of the directional dependence of the coupling efficiency from decay rates of the SPP and the fluorescent material --- p.11 / Chapter 1.4 --- Organization of the thesis --- p.12 / Chapter Chapter 2 --- Theory of surface plasmon polaritons --- p.14 / Chapter 2.1 --- The Maxwell’s equations and the boundary conditions for electromagnetic waves --- p.14 / Chapter 2.2 --- Dielectric constant of metal --- p.18 / Chapter 2.3 --- Master equation for electromagnetic waves, the Bloch form of SPPs and the dispersion relation of SPPs at the interface between dielectric and metal --- p.19 / Chapter 2.4 --- Excitation of surface plasmon polaritons by grating coupling --- p.27 / Chapter 2.5 --- Decay of surface plasmon polaritons --- p.29 / Chapter 2.5.1 --- Non-radiative decay --- p.29 / Chapter 2.5.2 --- Radiative decay --- p.31 / Chapter Chapter 3 --- Experimentation and Simulation --- p.37 / Chapter 3.1 --- Sample preparation --- p.37 / Chapter 3.1.1 --- Interference lithography [2.2, 3.7, 3.8] --- p.37 / Chapter 3.1.2 --- E-beam evaporation --- p.39 / Chapter 3.1.3 --- Spin coating of florescence material --- p.40 / Chapter 3.2 --- Measurements --- p.41 / Chapter 3.2.1 --- Angle-resolved specular reflection measurement [3.10] --- p.42 / Chapter 3.2.2 --- Angle-resolved photoluminescence (PL) spectroscopy [3.11] --- p.43 / Chapter 3.2.3 --- K-space (Fourier space) imaging [3.12, 3.13, 3.14] --- p.44 / Chapter 3.3 --- FDTD --- p.46 / Chapter 3.3.1 --- Theory of FDTD --- p.46 / Chapter 3.3.2 --- Simulation of the reflectivity of plane wave --- p.52 / Chapter 3.3.3 --- Simulation of the field pattern with a dipole source --- p.55 / Chapter 3.3.3.1 --- Near-to-far field projection --- p.59 / Chapter 3.3.3.2 --- Near field pattern in k-space --- p.60 / Chapter Chapter 4 --- Analysis --- p.62 / Chapter 4.1 --- Angle-resolved reflectivity measurement --- p.62 / Chapter 4.1.1 --- SPP mode identification --- p.62 / Chapter 4.1.2 --- Wavelength dependence of uncoupled SPPs decay rates --- p.65 / Chapter 4.1.3 --- Directional dependence of uncoupled SPPs decay rates --- p.71 / Chapter 4.2 --- Angle-resolved PL spectroscopy --- p.79 / Chapter 4.2.1 --- Comparison with the angle-resolved reflectivity --- p.79 / Chapter 4.2.2 --- Differentiation of the resonance and off-resonance positions on the PL mapping --- p.81 / Chapter 4.3 --- K-space imaging --- p.83 / Chapter 4.3.1 --- Reflectivity and the comparison with the phase - matching equation --- p.83 / Chapter 4.3.2 --- k-space imaging of the PL emission --- p.85 / Chapter 4.4 --- Directional dependence of the emission factor --- p.86 / Chapter 4.5 --- Directional dependence of the coupling rate of the LDS emission to the SPP mode --- p.94 / Chapter 4.6 --- Near field in k-space from the FDTD method --- p.97 / Chapter Chapter 5 --- Conclusions --- p.113 / Bibliography --- p.115

While silicon has long been utilized for its electronic properties, its use as an optical material has largely been limited due to the poor efficiency of interband transitions. However, discovery of visible photoluminescence (PL) from nanocrystalline silicon in 1990 triggered many ensuing research efforts to optimize PL from nanocrystalline silicon for optical applications. Currently, use of photoluminescent silicon nanoparticles (Si NPs) is commercially limited by: 1) the instability of the energy and intensity of the PL, and 2) the low quantum yield of interband PL from Si NPs. Herein, red-emitting, hydrogen-passivated silicon nanoparticles (H-Si NPs) were synthesized by thermally-induced disproportionation of a HSiCl3-derived (HSiO1.5)n polymer. The H-Si NPs produced by this method were then subjected to various chemical and physical environments to assess the long-term stability of the optical properties as a function of changing surface composition. This dissertation is intended to elucidate correlations between the reported PL instability and the observed changes in the Si NP surface chemistry over time and as a function of environment. First, the stability of the H-Si NP surface at slightly elevated temperatures towards reactivity with a simple alkane was probed. The H-Si NPs were observed by FT-IR spectroscopy to undergo partial hydrosilylation upon heating in refluxing hexane, in addition to varying degrees of surface oxidation. The unexpected reactivity of the Si surface in n-hexane supports the unstable nature of the H-Si NP surface, and furthermore implicates the presence of highly-reactive Si radicals on the surfaces of the Si NPs. We propose that reaction of alkene impurities with the Si surface radicals is largely responsible for the observed surface alkylation. However, we also present an alternate mechanism by which Si surface radicals could react with alkanes to result in alkylation of the surface. Next, the energy and intensity stability of the interband PL from H-Si NPs in the presence of a radical trap was probed. Upon addition of (2,2,6,6,-tetramethyl-piperidin-1-yl)oxyl (TEMPO), the energy and intensity of the interband transition was observed to change over time, dependent on the reaction conditions. First, when the reaction occurred at 4ºC with minimal light exposure, the interband transition exhibited a gradual hypsochromic shift to between 595 nm and 655 nm, versus the λmax of the original low energy emission peak at 700 nm, depending on the amount of TEMPO in the sample. Second, when the reaction proceeded at room temperature with frequent exposure to 360 nm irradiation, the original interband transition at 660 nm was quenched while a new peak at 575 nm developed. Based on all the data collected and analyzed, we assign the 595 -- 655 nm transition as due to interband exciton recombination from Si NPs with reduced diameters relative to the original Si NPs. We furthermore assign the 575 nm transition as due to an oxide-related defect state resulting from rapid oxidation of photo-excited Si NPs.

D.Ing. (Electrical And Electronic Engineering ) / Please refer to full text to view abstract

Metasurfaces are nanostructured interfaces capable of manipulating the phase, amplitude, or polarization of free-space light. ‘Local’ metasurfaces typically control the wavefront shape of spectrally broadband light to generate devices such as flat lenses, holograms, and beam steerers. In contrast, ‘nonlocal’ metasurfaces, such as photonic crystals, support spatially-extended optical modes that govern the transmission or reflection spectrum. Therefore, local metasurfaces typically offer spatial control over incident light but not spectral control, while nonlocal metasurfaces impose spectral but not spatial control. This thesis explores nonlocal dielectric metasurfaces with simultaneous spatial and spectral control such that they shape the wavefront only for spectrally narrowband resonant modes but act like an unpatterned substrate for non-resonant light. These devices are formulated from a rational design scheme based on symmetry arguments. Chapter 1 reviews the theoretical basis for these devices. Chapters 2 and 3 discuss experimental demonstrations of nonlocal wavefront-shaping metasurfaces in the near-infrared and visible wavelength regions, respectively. Our initial experimental demonstrations in the near-infrared in silicon metasurfaces were the first verification of their theoretical proposal. In the visible, experimental results of metasurfaces made of silicon-rich silicon nitride suggest potential applications in transparent displays, augmented reality headsets, and quantum optics. Significantly, our nonlocal metasurfaces form a versatile platform for multifunctional and multicolor meta-optics that shape the wavefront distinctively at several different resonant wavelengths, which we have experimentally demonstrated in both the near-infrared and the visible. Chapters 4 and 5 discuss conceptualization and experimentally demonstration of thermally-tunable nonlocal wavefront-shaping metasurfaces. Reconfigurable photonic devices such as zoom lenses and dynamic holograms have posed a substantial challenge and captured the interest of the optics community. We leverage the enhanced light-matter interaction in our nonlocal wavefront-shaping metasurfaces to realize tunable wavefront-shaping using conventional dielectric materials and standard nanofabrication procedures. The operating principle of these devices is that tuning the refractive index of the device with the thermo-optic effect can align or detune the resonant wavelength of a mode from the wavelength of a narrowband incident light source, and the wavefront is shaped only when the optical resonance is spectrally aligned with the incident light. Experimentally, we have demonstrated nonlocal metasurfaces based on structured germanium thin films whose functionality can be thermally switched between that of two different lenses. The thesis is concluded with a section on future prospects.

Zhao, Lei = 介孔材料的光學應用和表面等離子體-熒光分子之間相互作用 / 趙磊. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Zhao, Lei = Jie kong cai liao de guang xue ying yong he biao mian deng li zi ti - ying guang fen zi zhi jian xiang hu zuo yong / Zhao Lei.