In addition, this project also investigated schemes that might enhance the phase change in the SPR sensor. The "double-pass" and "multi-pass" approaches through which the SPR phase can be amplified upon hitting the sensor surface more than once, have been experimentally studied and successfully demonstrated. A double-pass method can immediately offer two times of phase change as compared to the singlepass one. Accordingly the multi-pass scheme offers a higher then two times phase enhancement. Such improvement in phase detection is extremely important for biosensing applications involving small molecules, small proteins, DNA and etc. Another approach for detection performance improvement is to incorporate a multilayer configuration for the biosensing surface. In order to improve the dynamic measurement response, we proposed to use a multiple resonant angle measurement approach in conjunction with the single-beam self-referenced phase-sensitive SPR configuration. With the use of many multiple incident angles, the system provided sensing capability that covers a refractive index (RI) 1.33 to over 1.38. A 128-element array detector was employed to measure the resonance phase change over the range of the incident angles to ensure a reasonably continuous phase response curves achievable from the system. / This project is concerned with the development and optimization of optical sensors based on measuring the phase change of surface plasmon resonance (SPR) effect. The phase sensitive SPR technique provides very high sensitivity performance due to the fact that an abrupt phase jump occurs near the resonance dip, thus resulting in large phase shift with very small change in the sensing medium. A range of different measurement techniques for enhancing system sensitivity have been investigated. Moreover we also studied the phase change characteristics around the SPR dip region by means of simulation in order to explore various approaches for achieving further improvement in sensitivity and as well as wide dynamic range. Since SPR is caused by electron charge density oscillations in metal surface in which the wave momentum required for plasmon wave excitation is always larger than that for free space, an inverted prism-coupling scheme (prism-metal-dielectric) is commonly used and this configuration was also employed in our experimental setup, particularly for the SPR biosensor based on differential phase Mach-Zehnder interferometer configuration. This design primarily operates by taking advantage of the fact that SPR only affects the p-polarization while leaving the s-polarization unchanged. This means that differential phase measurement between the p- and s- polarizations will result in SPR signals that are completely free from any disturbances that are common to both channels. Experimental results obtained from glycerin/water mixtures indicate that the sensitivity limit of our scheme is 5.48 x 10 -8 refractive index unit per 0.01° phase change. To our knowledge, this is a significant improvement over previously obtained results when gold is used as the sensor surface. While acknowledging that accurate optical alignment is a crucial requirement for the Mach-Zehnder interferometer and it is often not easy to maintain high degree alignment accuracies in practical situations, we have developed a versatile and low cost single-beam self-referenced phase-sensitive surface SPR sensing system. The system exhibits a root-mean-square phase fluctuation of +/-0.0028° over a period of 45 minutes, i.e. a resolution of +/-5.2x10 -9 refractive index units. The enhanced performance has been achieved through the incorporation of three design elements: (i) a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected; (ii) a differential measurement scheme to eliminate spurious signals not related to the sensor response; (iii) elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulator. Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional florescence-based techniques. / Wu, Shu Yuen. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 132-147). / 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, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

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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.

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.

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Polarimetry, as applied to chemical analysis, deals with the determination of the extent and direction that an optically active chemical species will rotate incident linearly polarized light. Although well developed for physical sensing, the technique of fiber optic polarimetry for chemical sensing remains in its infancy. This thesis is concerned with the design and development of an optical fiber polarimeter which measures the optical rotation of linearly polarized light that occurs in a sensing region between two multi-mode optical fibers. Over short distances, the polarization preserving capabilities of large-core multi-mode optical fibers were investigated. Polarimetric analyses were performed using sucrose and quinine hydrochloride. The instrument has a resolution of 0.08·, and is an excellent platform for an LC or FIA detector. Its more intriguing future lies in evanescent field sensor applications and studies of chiroptical surface interactions. / Master of Science

Trends toward increased integration and miniaturization of optical system components have created pressure to consolidate widely disparate analog and digital functions onto fewer and fewer chips with a goal of eventually built into a single mixed-signal chip. Yet, because of those performance requirements, the frontend circuit has traditionally used III-V compound semiconductor technologies, but the low-level of integration with other digital ICs limits the sustainability of such end products for short-distance applications. On the other hand, their CMOS counter parts, despite having such advantages as low power consumption, high yield that lowers the cost of fabrication, and a higher degree of integration, have not performed well enough to survive in such a noisy environment without sacrificing other important attributes. In this research, a high-speed CMOS preamplifier was designed and fabricated through TSMC 0.18/spl mu/m mixed-signal non-epi CMOS technology, and a 20/spl mu/m diameter InGaAs thin-film Inverted-MSM photodetector with a responsivity of 0.15A/W at a wavelength of 1550/spl mu/m was post-integrated onto the circuit. The circuit has a overall transimpedance gain of 60dB/spl Omega/, and bit-error-rate data and eye-diagram measurement results taken as high as 10Gbit/s are reported in this dissertation.