The operating principles and design of an optical receiver for a Light Detection and Ranging (LIDAR) remote sensing instrument are addressed. The performance and limitations of a biaxial monostatic LIDAR system utilizing this design are investigated. The complete optical and structural design of the receiver, including specifications of components are outlined. The thermal stabilization of the detector assembly and the integration of control electronics are described. A detailed discussion of alignment procedures and possible improvements are made. A sample observation is presented with suggestions for fully automating the system.

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

Zhou, Shengli. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 133-140). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

The market for higher data rate communication is driving the semiconductor industry to develop new techniques of writing at smaller scales, while continuing to scale bandwidth at low power consumption. The question arises of how to continue to sustain this trend. Silicon photonic (SiPh) devices offer a potential solution to the electronic interconnect bandwidth bottleneck. SiPh leverages the technology commensurate of decades of fabrication development with the unique functionality of next-generation optical interconnects. Finer fabrication techniques have allowed for manufacturing physical characteristics of waveguide structures that can support multiple modes in a single waveguide. By refining modal characteristics in photonic waveguide structures, through mode multiplexing with the asymmetric y-junction and microring resonator, higher aggregate data bandwidth is demonstrated via various combinations of spatial multiplexing, broadening applications supported by the integrated platform. The main contributions of this dissertation are summarized as follows. Experimental demonstrations of new forms of spatial multiplexing combined together exhibit feasibility of data transmission through mode-division multiplexing (MDM), mode-division and wavelength-division multiplexing (MDM-WDM), and mode-division and polarization-division multiplexing (MDM-PDM) through a C-band, Si photonic platform. Error-free operation through mode multiplexers and demultiplexers show how data can be viably scaled on multiple modes and with existing spatial domains simultaneously. This work opens up new avenues for scaling bandwidth capacity through leveraging orthogonal domains available on-chip, beyond what had previously been employed like WDM and time-division multiplexing (TDM). Furthermore, we explore expanding device channel support from two to three arms. Finding that a slight mismatch in the third arm can increase crosstalk contributions considerably, especially when increasing data rate, we explore a methodical way to design the asymmetric y-junction device by considering its angles and multiplexer/demultiplexer arm width. By taking into consideration device fabrication variations, we turn towards optimizing device performance post-fabrication. Through ModePROP simulations, optimizing device performance dynamically post-fabrication is analyzed, through either electro-optical or thermo-optical means. By biasing the arm introducing the slight spectral offset, we can quantifiably improve device performance. Scaling bandwidth is experimentally demonstrated through the device at 3 modes, 2 wavelengths, and 40 Gb/s data rate for 240 Gb/s aggregate bandwidth, with the potential to reduce power penalty per the device optimization process we described. A main motivation for this on-chip spatial multiplexing is the need to reduce costs. As the laser source serves as the greatest power consumer in an optical system, mode-division multiplexing and other forms of spatial multiplexing can be implemented to push its potentially prohibitive cost metrics down. While the device introduces loss, through imperfect mode isolation, as device fabrication improves, tolerance can increase as well. Meanwhile, the rate that laser power consumption increases as supported wavelengths scales is shown to be much faster than the loss introduced by scaling on-chip bandwidth multi-modally. Future generations of ultra-high capacity devices through spatial multiplexing is explored. Already various systems can be implemented multimodally, with the design features serving as useful for other components. Central to photonic network-on-chips, a multimodal switch fabric, composed of microring resonators, is demonstrated to have error-free operation of 1x2 switching of 10 Gb/s data. These contributions aim to scale bandwidth to ultra-high capacity, while ameliorating any imperfect design, through multiple routes conjoined with on-chip spatial multiplexing, and they constitute the bulk of this dissertation. For the latter part, we turn to the issue of integrating a photonic device for dynamic power reallocation in a system. Specifically, we utilize a 4x4 nonblocking switch fabric composed of Mach-Zehnder interferometers that switch both electro-optically and thermo-optically at ns and μs rates respectively. In order to demonstrate an intelligent platform capable of dynamically multicasting data and reallocating power as needed by the system, we must first initialize the switch fabric to control with an electronic interface. A dithering mechanism, whereby exact cross, bar, and sub-percentage states are enforced through the device, is described here. Such a method could be employed for actuating the device table of bias values to states automatically. We then employ a dynamic power reallocation algorithm through a data acquisition unit, showing real-time channel recovery for channels experiencing power loss by diverting power from paths that could tolerate it. The data that is being multicast through the system is experimentally shown to be error-free at 40 Gb/s data rate, when transmitting from one to three clients and going from automatic bar/cross states to equalized power distribution. For the last portion of this topic, the switch fabric was inserted into a high-performance computing system. In order to run benchmarks at 10 Gb/s data ontop of the switch fabric, a newer model of the control plane was implemented to toggle states according to the command issued by the server. Such a programmable mechanism will prove necessary in future implementations of optical subsystems embedded inside larger systems, like data centers. Beyond the specific control plane demonstrated, the idea of an intelligent photonic layer can be applied to alleviate many kinds of optical channel abnormalities or accommodate for switching based on different patterns in data transmission. Besides spatial-multiplexing, expanding on-chip bandwidth can be accomplished by extension of the wavelength detection regime to a longer regime. Experimental demonstration of photodetection at 1.9 μm is shown with Si+-doped Si photodetectors at 1 Gb/s data operation featuring responsivities of .03 AW−1 at 5 V bias. The same way of processing these Si ribbed waveguide photodetectors can garner even longer wavelength operation at 2.2 μm wavelength. Finally, the experimental demonstration of a coherent perfect absorption Si modulator is exhibited, showing a viable extinction ratio of 24.5 dB. Using this coherent perfect absorption mechanism to demodulate signals, there is the added benefit of differential reception. Currently, an automated process for data collection is employed at a faster time scale than instabilities present in fibers in the setup with future implementations eliminating the off-chip phase modulator for greater signal stability. The field of SiPh has developed to a stage where specific application domains can take off and compete according to industrial-level standards. The work in this dissertation contributes to experimental demonstration of a newly developing area of mode-division multiplexing for substantially increasing bandwidth on-chip. While implementing the discussed photonic devices in dynamic systems, various attributes of integrated photonics are leveraged with existing electronic technologies. Future generations of computing systems should then be designed by implementing both system and device level considerations.

Optical detection devices such as optical biosensors and optical spectrometers are widely used in many applications for the functions of measurements, inspections and analysis. Due to the large dimension of prisms and gratings, the traditional optical devices normally occupy a large space with complicated components. Since cheaper and smaller optical devices are always in demand, miniaturization has been kept going for years. Thanks to recent fabrication advances, nanophotonic devices such as semiconductor laser chips have been growing in number and diversity. However, the optical biosensor chips and the optical spectrometer chips are seldom reported in the literature. For the reason of improving system integration, the study of ultra-compact, low-cost, high-performance and easy-alignment optical biosensors and optical spectrometers are imperative. This thesis is an endeavor in these two subjects and will present our research work on studying the optical transmission properties of dielectric aperture arrays and developing new optical biosensors and optical spectrometers. / Subsequently, optical transmission properties through a self-mixing interferometer array are studied and a novel high-resolution cost-effective optical spectrometer is proposed. The miniature interferometer-based spectrometer is made of polymethyl methacrylate (PMMA) with a CCD as the detector. The detected intensity of each CCD pixels contains the spectral information. Since each frequency component in the incoming beam corresponds to a unique phase difference of the two beam portions of each optical interferometer, the total intensity received by each CCD pixel, which is resulted from the addition of the interference signals from all the frequency components in the beam, should also be unique. Therefore, the spectrum calculation is a problem to solve an ill-posed linear system by using Tikhonov regularization method. Simulation results show that the resolution can reach picometer level. Apart from the choice of path difference between the interfering beams, the spectral resolution also depends on the signal-to-noise ratio and analogue-digital conversion resolution (dynamic range) of the CCD chip. In addition, the theory of uniform waveguide scattering is explored to expand the possibility of using such mini-interferometers for performing free-space spectral analysis of waveguide devices. At the same time, the method of least squares is used to correct the pixel non-uniformity of the CCD so as to improve the performance of the spectrometer. / The first half of the thesis demonstrates that the optical phase shift associated with the surface plasmon (SP) assisted extraordinary optical transmission (EOT) in nano-hole arrays fabricated in a metal film has a strong dependence on the material refractive index value in close proximity to the holes. A novel refractive index sensor based on detecting the EOT phase shift is proposed by building a model. This device readily provides a 2-D biosensor array platform for non-labeled real-time detection of a variety of organic and biological molecules in a sensor chip format, which leads to a high packing density, minimal analyte volumes, and a large number of parallel channels while facilitating high resolution imaging and supporting a large space-bandwidth product (SBP). Simulation (FDTD Solutions, Lumerical Solutions Inc) results indicate an achievable sensitivity limit of 4.37x10-9 refractive index units (RIU) and a dynamic range as large as 0.17 RIU. / The sensor chip and spectrometer chip introduced here are based on the interference of light transmitted through dielectric aperture arrays. Their compact feature renders these devices ideal for miniaturization and integration as the systems in microfluidics architectures and lab-on-chip designs. / Yang, Tao. / Adviser: H. P. Ho. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 150-163). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Gong, Yibo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (p. 99-108). / Abstracts in English and Chinese. / Abstract --- p.ii / Acknowledgement --- p.v / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation and Objective --- p.1 / Chapter 1.2 --- Contributions --- p.4 / Chapter 1.2.1 --- Embedded fire detection platform --- p.4 / Chapter 1.2.2 --- Extended CAMSHIFT object detection frame work --- p.5 / Chapter 1.2.3 --- Cooperative multiple camera module --- p.8 / Chapter 1.2.4 --- Aerial maritime survivor detection system --- p.9 / Chapter 1.3 --- Organization of this thesis --- p.9 / Chapter 2 --- Background Study --- p.11 / Chapter 2.1 --- Embedded computer vision --- p.11 / Chapter 2.2 --- Visual Fire detection --- p.12 / Chapter 2.3 --- Color-based object detection and tracking --- p.15 / Chapter 2.4 --- Multiple-camera system cooperation --- p.16 / Chapter 2.5 --- Multiple-camera system calibration --- p.18 / Chapter 3 --- Overview of the embedded fire detection system --- p.22 / Chapter 3.1 --- Functional modules of the detection unit --- p.25 / Chapter 3.2 --- Dataflow within the detection unit --- p.28 / Chapter 4 --- Simulated annealing based MEAN SHIFT framework --- p.31 / Chapter 4.1 --- Simulated annealing framework --- p.33 / Chapter 4.2 --- Combination of simulated annealing with MEAN SHIFT --- p.37 / Chapter 5 --- Extended CAMSHIFT framework for fire detection --- p.42 / Chapter 5.1 --- Bidirectional color histogram training and backprojection --- p.43 / Chapter 5.2 --- Choice of properly sized fire window --- p.48 / Chapter 5.3 --- Alternative optimization based search window resizing --- p.49 / Chapter 5.4 --- Multiple modal particle filter based window size optimization --- p.53 / Chapter 5.4.1 --- Multiple modal particle filter --- p.53 / Chapter 5.4.2 --- Integration of the MMPF with CAMSHIFT framework --- p.57 / Chapter 5.5 --- fire monitoring --- p.63 / Chapter 6 --- The multiple camera module --- p.65 / Chapter 6.1 --- Calibration of the multi-camera system --- p.66 / Chapter 6.2 --- Region mapping and cooperation among the cameras --- p.69 / Chapter 7 --- Implementation and Experiments --- p.71 / Chapter 7.1 --- Implementation --- p.71 / Chapter 7.2 --- Experiments and performance evaluations --- p.74 / Chapter 7.2.1 --- Bidirectional histogram training and backprojection --- p.76 / Chapter 7.2.2 --- Performance of the hybrid Simulated annealing-Mean shift framework --- p.78 / Chapter 7.2.3 --- Alternative optimization based search window resizing for CAMSHIFT --- p.84 / Chapter 7.2.4 --- Multiple modal particle filter based search window resizing for CAMSHIFT --- p.87 / Chapter 7.2.5 --- Real-scenario test on the arm system --- p.94 / Chapter 7.2.6 --- Comparison of the two search window resizing mechanisms --- p.96 / Chapter 7.2.7 --- Accuracy of the multiple camera calibration method --- p.97 / Chapter 8 --- Extension to aerial maritime survivor search --- p.99 / Chapter 8.1 --- Introduction --- p.99 / Chapter 8.2 --- Implementation and experiment results --- p.102 / Chapter 9 --- Conclusion --- p.105 / Chapter 9.1 --- Contribution and summary of the work --- p.105 / Chapter 9.2 --- Future work --- p.107 / Bibliography --- p.109

High quality nanophotonic structures fabricated on silicon nitride substrates and operating in the visible range of the spectrum are investigated. As most biological sensing applications, such as Raman and fluorescence sensing, require visible light pumping and analysis, extending the nanophotonics concepts to the visible range is essential. Traditionally, CMOS compatible processes are used to make compact silicon nanophotonics structures. While the high index contrast of silicon on insulator (SOI) wafers offer a high integration capability, the high absorption loss of silicon renders it unusable in the visible range. In this research high quality factor microdisk and photonic crystal resonators and high resolution arrayed waveguide grating and superprism spectrometers are fabricated and characterized in the visible range and integrated with fluidic structures and their application in biosensing and athermal operations is investigated.

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