Electronic microchips have now firmly plateaued in switching speed. A promising solution for increasing performance on unparallelizable tasks is to switch digital data purely in the optical domain on a photonic chip, as all-optical switching can reach up to terahertz speeds and beyond. Because ultrafast optical effects are weak phenomena, materials with extremely high nonlinear sensitivity must be developed, and very high optical intensities and coupling efficiencies are required to adequately switch data streams of light. In this thesis, unique all-optical platforms, waveguides, fiber-waveguide grating couplers, and an ultrafast optical switch were experimentally demonstrated as proofs-of-concept for the validity of densely integrated all-optical switches. Two horizontal slot waveguiding structures were designed and fabricated from scratch: a multiple horizontal slot waveguide with polycrystalline silicon sandwiching third-order nonlinear slots and a nonlinear cover-cladding with slot-like behavior over a thin crystalline silicon waveguide. Perfectly vertical grating couplers were then designed from a novel genetic algorithm, fabricated, and experimentally tested for both platforms with two promising nonlinear materials: silicon nanocrystals or a supra-molecular assembly, DDMEBT. Vertical grating couplers in the multiple horizontal slot waveguide achieved a theoretical coupling efficiency of 63% and an experimental coupling efficiency of 60%, which is the highest coupling efficiency into nonlinear slot waveguides to date. Vertical grating couplers for the cover-slot waveguide experimentally demonstrated a coupling efficiency of 38% and an extrapolated 1 dB bandwidth of 66 nm, the largest grating-coupled 1 dB bandwidth obtained for slot waveguides to date. A grating coupler was then designed to be included as one of two grating reflectors in a nonlinear resonator switch. Coupled mode theory and vectorial eigenmode propagation simulations were used to optimally design the grating coupler/resonator device, resulting in a record low footprint of 710 μm² per combined switch and fiber coupler device. The third-order nonlinear molecular material, DDMEBT, was, for the first time, successfully spun onto pre-patterned silicon-on-insulator chips with repeatable, defect-free results. Extremely sensitive experimental autocorrelation of the resonator's impulse response yielded output pulse durations as low as 600 femtoseconds. At high power and low pulse repetition rates, the switch's resonances redshifted by 4 nm with 4 dB of switching contrast, revealing an ultrafast Kerr effect which matched previous works. The resonator switch is therefore capable of modulating a single optical carrier frequency at 1 THz and switching an optical data stream at 500 GHz. These are the fastest switching speeds demonstrated by an integrated all-optical switch and validate the proof-of-concept needed for a future of densely integrated all-optical processing. / text

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Zhao Yang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 87-95). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Objectives of the Thesis --- p.1 / Chapter 1.2 --- Wafer bumping inspection by using Biplanar Disparity approach --- p.2 / Chapter 1.3 --- Thesis Outline --- p.4 / Chapter 2 --- Background --- p.5 / Chapter 2.1 --- What is wafer bump? --- p.5 / Chapter 2.1.1 --- Common defects of wafer bump --- p.6 / Chapter 2.1.2 --- Literature review on exist wafer bump inspection method --- p.11 / Chapter 3 --- Model 1: the one camera model-Homography approach --- p.21 / Chapter 3.1 --- The introduction of the theoretical base of model 1 --- p.21 / Chapter 3.1.1 --- The objective of model 1 --- p.21 / Chapter 3.1.2 --- Desires --- p.22 / Chapter 3.1.3 --- Some background knowledge on Homography --- p.22 / Chapter 3.2 --- "Model 1- ""Pseudo Homography"" Approach" --- p.24 / Chapter 3.2.1 --- The description of the configuration of model 1 --- p.24 / Chapter 3.2.2 --- The condition of pseudo Homography --- p.25 / Chapter 3.2.3 --- The formation of pseudo Homgraphy H --- p.26 / Chapter 3.3 --- Methodology of treatment of the answer set --- p.32 / Chapter 3.3.1 --- Singular Value Decomposition-SVD --- p.32 / Chapter 3.3.2 --- The Robust Estimation --- p.33 / Chapter 3.3.3 --- Some experimental results by using manmade Ping Pang balls to test SVD[31] and Robust Estimation [24] --- p.35 / Chapter 3.3.4 --- the measurement of the Homography matrix answer set --- p.37 / Chapter 3.4 --- Preliminary experiment about model 1 --- p.43 / Chapter 3.5 --- Problems unsolved --- p.47 / Chapter 4 --- Model 2: the two camera model-Biplanar Disparity approach --- p.48 / Chapter 4.1 --- Theoretical Background --- p.48 / Chapter 4.1.1 --- the linearization of Homography matrix changes --- p.49 / Chapter 4.1.2 --- Problem Nature --- p.51 / Chapter 4.1.3 --- Imaging system setup --- p.52 / Chapter 4.1.4 --- Camera Calibration[13] --- p.52 / Chapter 4.2 --- Methodology --- p.54 / Chapter 4.2.1 --- Invariance measure --- p.54 / Chapter 4.2.2 --- The Geometric meaning of the Biplanar Disparity matrix --- p.58 / Chapter 4.3 --- RANSAC-Random Sample Consensus --- p.64 / Chapter 4.3.1 --- finding Homography matrix by using RANSAC[72] [35] --- p.64 / Chapter 4.3.2 --- finding Fundamental matrix by using RANSAC[73] [34] --- p.65 / Chapter 4.4 --- Harris Corner detection --- p.65 / Chapter 5 --- Simulation and experimental results --- p.67 / Chapter 5.1 --- Simulation experiments --- p.67 / Chapter 5.1.1 --- Preliminary experiments --- p.67 / Chapter 5.1.2 --- Specification for the synthetic data system --- p.71 / Chapter 5.1.3 --- Allowed error in the experiment --- p.71 / Chapter 5.2 --- Real images experiments --- p.72 / Chapter 5.2.1 --- Experiment instrument --- p.72 / Chapter 5.2.2 --- The Inspection Procedure --- p.74 / Chapter 5.2.3 --- Images grabbed under above system --- p.75 / Chapter 5.2.4 --- Experimental Results --- p.81 / Chapter 6 --- CONCLUSION AND FUTURE WORKS --- p.83 / Chapter 6.1 --- Summary on the contribution of my work --- p.83 / Chapter 6.2 --- Some Weakness of The Method --- p.84 / Chapter 6.3 --- Future Works and Further Development --- p.84 / Chapter 6.3.1 --- About the synthetic experiment --- p.84 / Chapter 6.3.2 --- About the real image experiment --- p.85 / Bibliography --- p.87

M.S. / Electrical Engineering / The efficient coupling between a semiconductor laser and a single-mode fiber is a key element for fully utilizing the single-mode fiber for the optical communication. In this thesis, the Gaussian beam approach is used for analyzing the coupling of a single-mode laser diode to a single-mode optical fiber by a microlens. Two analytical methods based on both the ABCD law and the diffraction theory are presented. The effect of a microlens on both the phase and amplitude of a Gaussian beam are discussed in detail. The presented analysis specifies the optimum coupling in terms of laser and fiber parameters and the laser to fiber distance. Furthermore, the coupling efficiencies achievable in hemispheric and etched conical microlenses systems are explicitly compared. The present analysis shows that a coupling efficiency as high as 62% is achievable with the optimal choice of laser and fiber parameters. Additionally, theoretically obtained coupling efficiency is compared with the experimental data for both butt and etched fibers.

M.S. / Electrical Engineering / Surface-emitting laser diodes are of interest for various applications such as monolithic two-dimensional arrays and optical interconnects for integrated optics. Therefore, it is essential to characterize these lasers. The farfield radiation pattern is one of the important characteristics of a laser diode. In this thesis the farfield of a surface-emitting laser diode with a turning mirror is modeled and measured. The computer simulation uses a rigorous theoretical expression for the field at the output mirror laser-air interface derived by Davies and Walpole and then using a modified form of the Kirchoff diffraction integral to generate the farfield. The computer modeling is done for both flat 45° and parabolic turning mirrors. Experimental data were also obtained for a surface-emitter with a 45° straight turning mirror. This mirror was fabricated using the focused ion beam micromachining technique developed at OGC. In the case of the parabolic turning mirror, the experimental results published by Liau and Walpole were used. A comparison of theoretical and experimental results for the two shapes of mirrors is also presented.

Thesis (Ph. D.)--Ohio State University, 2002. / Title from first page of PDF file. Document formatted into pages; contains xv, 145 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Betty Lisle Anderson, Dept. of Electrical Engineering. Includes bibliographical references (p. 140-145).

Thesis--PlanB (M.S.)--University of Wisconsin--Stout, 2001. / Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references.

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