This thesis is mainly a survey of optical devices used in optical logic and optical space, time and frequency division switching. These are mainly optical logic devices, optical switches, optical switching matrices, optical memories and optical wavelength multiplexers and demultiplexers and optical wavelength shifters. The devices are based on a variety of operating principles and are implemented with a variety of technologies. The basic principles and technologies are described together with typical performance parameters. The different devices and technologies are compared, and areas of possible improvements indicated. As an application of this survey, the possibility of implementing optical logic circuits and an optical time-division switch for Sonet based transmission systems is discussed. / Master of Science

The extended describing function method is proposed as a systematic small-signal modeling approach to nonlinear switching circuits. This method offers significant simplification upon the previous work on using the multi-variable describing functions to treat the circuit nonlinearities. As an extension to the statespace averaging method, this modeling technique can incorporate any Fourier components for good model accuracy and provides continuous-time small-signal models for PWM topologies and various soft-switching resonant topologies. The proposed method is demonstrated using four resonant topologies and two multi-resonant topologies. These circuits are strongly oscillatory, and thus they cannot be modeled by means of traditional averaging techniques. By employing the proposed modeling method, the dynamics of the resonant converters are analyzed with emphasis on the nonlinear interaction between the switching frequency and the circuit natural resonant frequency. Equivalent circuit models are provided for more convenience of practical designs. Small-signal analysis is also performed for two challenging multi-resonant topologies with complex structure and operation. All of the theoretical models are verified experimentally and the predictions are well supported by the measurement data up to the Nyquist frequency. / Ph. D.

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全光信息處理被認為是其中一種改善當今計算機網絡性能的方法。而高效率的全光信息處理需要使用可用低強度的控制激光來控制的全光學開關。最近有人提出利用橫向光學圖案製造低強度全光學開關，並已通過原子蒸氣系統的實驗證明這個計劃的可行性。此外，相關的研究正在半導體量子阱微腔中進行。 / 這篇論文以微觀多體理論研究被激光正向入射的半導體量子阱微腔系統中產生的自發性橫向光學圖案。入射光會在一定條件下於半導體量子阱微腔中發生極化子場之間的自發四波混頻，並產生橫向光學圖案。我們分別以半分析和數值模擬的方法研究這些圖案的形成和選擇方式。本論文亦研究了如何用離軸激光和腔的各向異性來控制這些圖案。 / 我們分別用「多- / Processing information all-optically is thought to be one way to improve the performance of present-day computational network. Low intensity all-optical switches are desirable for effective all-optical information processing. Recently, low intensity all-optical switching schemes utilizing transverse optical patterns have been proposed. One such scheme was successfully demonstrated experimentally in an atomic vapour system, and a similar scheme is being studied both theoretically and experimentally in semiconductor quantum well micro-cavities. / In this thesis, we present our theoretical studies on the spontaneous transverse optical patterns produced by a semiconductor quantum well microcavity, pumped by a normally incident laser, using a microscopic many-body theory. Far field transverse optical patterns are formed under certain conditions by spontaneous four-wave mixing of the exciton-photon polariton field. The formation and the selection of these patterns are studied by both semi-analytical calculations and numerical simulations. The controls of transverse patterns using anisotropy in the microcavity and an o-axis control beam are also being studied in this thesis. / Two reduced models, the ‘multi- / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Luk, Ming Ho = 對半導體量子阱微腔中橫向光學圖案的控制 / 陸名浩. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 136-141). / Abstracts also in Chinese. / Luk, Ming Ho = Dui ban dao ti liang zi jing wei qiang zhong heng xiang guang xue tu an de kong zhi / Lu Minghao. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Pattern formation and nonlinear optics --- p.5 / Chapter 1.2 --- All-optical switching --- p.8 / Chapter 1.3 --- Semiconductor quantum well microcavity --- p.9 / Chapter 2 --- Semiconductor quantum well microcavity --- p.13 / Chapter 2.1 --- The structure of semiconductor quantum well microcavity --- p.14 / Chapter 2.2 --- Coupling between the cavity mode and external fields --- p.18 / Chapter 2.3 --- Microscopic theory in the microcavity --- p.22 / Chapter 3 --- Linear stability analysis and reduced models --- p.32 / Chapter 3.1 --- Pump only system - steady state solution --- p.32 / Chapter 3.2 --- Pump only system - stability analysis --- p.37 / Chapter 3.3 --- Off-axis stability studies --- p.39 / Chapter 3.3.1 --- Stability analysis without phase-space filling --- p.40 / Chapter 3.3.2 --- Linear stability analysis with phase-space filling --- p.54 / Chapter 3.4 --- Reduced models --- p.59 / Chapter 3.4.1 --- The multi- --- p.63 / Chapter 3.4.2 --- The ring model --- p.68 / Chapter 3.5 --- Effects of system parameters --- p.71 / Chapter 3.5.1 --- Radiative loss --- p.72 / Chapter 3.5.2 --- Incident laser field/intensity --- p.73 / Chapter 3.5.3 --- Fluctuations/weak constant sources --- p.78 / Chapter 4 --- Single-hexagon model --- p.82 / Chapter 4.1 --- Numerical results of single-hexagon model --- p.82 / Chapter 4.2 --- Pattern and time scale variations with parameters --- p.86 / Chapter 4.2.1 --- Anisotropy in the cavity mode energy --- p.87 / Chapter 4.2.2 --- Control beam intensity --- p.90 / Chapter 5 --- Dynamical analysis and interplay of wave-mixing processes --- p.93 / Chapter 5.1 --- Dynamical analysis --- p.93 / Chapter 5.2 --- Interplay of wave mixing processes --- p.99 / Chapter 5.3 --- Switching between hexagons --- p.103 / Chapter 6 --- Full two-dimensional simulation --- p.111 / Chapter 6.1 --- Convolution theorem and Fast Fourier Transform --- p.112 / Chapter 6.2 --- Simulation result and difficulties --- p.114 / Chapter 7 --- Other approaches --- p.119 / Chapter 7.1 --- Real Space Simulation --- p.119 / Chapter 7.2 --- Mode competition model --- p.121 / Chapter 7.3 --- Transfer Matrix --- p.123 / Chapter 8 --- Conclusion and outlook --- p.125 / Chapter 8.1 --- Future work --- p.128 / Chapter 8.1.1 --- Double Cavities --- p.128 / Chapter 8.1.2 --- The Gross-Pitaevskii Equation and Bose-Einstein Condensation --- p.131 / Bibliography --- p.136 / Chapter A --- Dispersion of cavity photon --- p.142

Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERONAUTICS. / Bibliography: leaf 86. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Charles Edward Harm. / M.S.

by Soung-yue Liew. / "June 1999." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (p. 159-169). / 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.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Thomas Raymond Zaloum. / M.S.

The use of switched linear networks is prevalent in power processing systems such as dc-to-dc power converters. These converters provide regulated dc output power and are widely used in the power supplies for computers and peripherals. As with most systems where high performance is a criterion, the power converter is usually enclosed in a feedback loop. Feedback design usually entails the use of small signal (linear) models with linear feedback design techniques. There exists a large number of small signal models, but most of them are ad hoc. A describing function approach has previously been presented which determines the exact small signal frequency response of the converters. This method is now used to systematically derive circuit models for power converters. The aim of the work presented in this thesis is to model the nonlinear part of the switching converters which are simply the switches. This study is focused on the Pulse Width Modulation (PWM) class of converters. Majority of available models are not very accurate because they are averaged models. The aim of the new approach is to obtain accurate and simple model. A partial realization of this aim has been achieved; the new model is accurate over a very wide frequency range, but presently the parameters are rather complicated.