This thesis reports the research and industry-related works carried out from the development of a fibre-optic strain sensor system for Civil Engineering applications. A sensor system consists of a number of core components, including the sensing element, interrogation/demodulation, multiplexing, signal processing and hardware equipment. In the process of development, a number of issues have been identified and investigated, which resulted in the improvement of the system performance, as well as the proposal of new techniques for the sensor system. First, an improved demodulation technique for a type of sensor, namely the fibre Fizeau interferometer (FFI), is presented. The technique is based on the improvement of the Fourier transform peak detection method, which suffers severely from the poor resolution and accuracy of finding the sensor cavity length. The improvement over the original method has been compared and verified through simulations and experiments. Second, a simultaneous demodulation technique for multiplexed FFI and fibre Bragg grating (FBG) sensors using the discrete wavelet transform (DWT) is proposed. Third, a multiplexing technique using amplitude-modulated chirped FBGs and the DWT is proposed. These two proposed techniques have been demonstrated experimentally through strain measurements. The strain resolution, crosstalk and limitations are investigated. In addition, simultaneous quasi-static strain and temperature sensing of different metal plates are performed. Fibre-optic sensors have found numerous applications in different areas. In this thesis, the use of FBG sensors in Civil Engineering applications is demonstrated in four experimental studies, including: (i) long-term measurement of drying shrinkage and creep of structural grade concrete; (ii) simultaneous measurement of shrinkage and temperature of reactive powder concrete (RPC) at early-age; (iii) measurement of coefficients of thermal expansion of cement mortar and RPC; and (iv) field-trial on the strain monitoring of the world?s first RPC road bridge. In addition, the experimental and practical issues of using FBG sensors are considered.

Structural born vibration is the most concern issue for industry. Traditionally, the accelerometer is usually used as the major monitoring device for vibration. As the mechanism getting more and more complexity, more compact, tinier and more lighting, the traditional accelerometers are suffered from the loading effect. Its accuracy of measurement is suspected and cannot match the modern measurement requirement. Hence, the studies of fiber optic vibration sensors become an urgent issue in this era. The reflection wavelength of a fiber Bragg grating¡]FBG¡^is sensitive to the variation of the strain and temperature. Our sensor configuration is made of an interferometer and fiber Bragg grating. The vibration induces a strain of the fiber Bragg grating, and it makes a phase difference between those two light beams in the interferometer. A demodulation circuit is needed to detect the phase difference caused by the vibration. In this project, the aim is focused on the vibration measurement for some complicated rotational machines or structures. A fiber optic accelerometer will be designed and studied as a vibration monitor for the other subprojects. In this the thesis, two kinds of vibration sensor head are designed and studied, the first is a bending loss sensor head and the other is an optic fiber Bragg grating sensor head. The results are narrated as follows¡G¡]1¡^ The dynamic range of the bending loss sensing head is about 50 dB.¡]2¡^The dynamic range of the optic fiber Bragg grating sensing head is 38 dB with test frequency range between 100 ~ 400 Hz, the noise level is around 1.95 ¡Ñ 10-2 rad.

This thesis reports the research and industry-related works carried out from the development of a fibre-optic strain sensor system for Civil Engineering applications. A sensor system consists of a number of core components, including the sensing element, interrogation/demodulation, multiplexing, signal processing and hardware equipment. In the process of development, a number of issues have been identified and investigated, which resulted in the improvement of the system performance, as well as the proposal of new techniques for the sensor system. First, an improved demodulation technique for a type of sensor, namely the fibre Fizeau interferometer (FFI), is presented. The technique is based on the improvement of the Fourier transform peak detection method, which suffers severely from the poor resolution and accuracy of finding the sensor cavity length. The improvement over the original method has been compared and verified through simulations and experiments. Second, a simultaneous demodulation technique for multiplexed FFI and fibre Bragg grating (FBG) sensors using the discrete wavelet transform (DWT) is proposed. Third, a multiplexing technique using amplitude-modulated chirped FBGs and the DWT is proposed. These two proposed techniques have been demonstrated experimentally through strain measurements. The strain resolution, crosstalk and limitations are investigated. In addition, simultaneous quasi-static strain and temperature sensing of different metal plates are performed. Fibre-optic sensors have found numerous applications in different areas. In this thesis, the use of FBG sensors in Civil Engineering applications is demonstrated in four experimental studies, including: (i) long-term measurement of drying shrinkage and creep of structural grade concrete; (ii) simultaneous measurement of shrinkage and temperature of reactive powder concrete (RPC) at early-age; (iii) measurement of coefficients of thermal expansion of cement mortar and RPC; and (iv) field-trial on the strain monitoring of the world?s first RPC road bridge. In addition, the experimental and practical issues of using FBG sensors are considered.

This thesis investigates the generation and radio-over-fibre (RoF) transport of unlicensed 60 GHz millimetre-wave (mm-wave) frequency band. The investigated benefits of transmission schemes applicable for the mm-wave generation include optical carrier suppression (OCS), optical frequency multiplication (OFM) and remote heterodyne detection (RHD). For the in-door cabling of the mm-wave transmission, a low-cost polymer optical fibre (POF) along with bend-insensitive single mode fibre (BI-SMF) has been investigated for short-range networks. Transporting mm-wave generated signals over POF and BI-SMF cables based on OCS scheme showed results with the highest spectral efficiency and least inter-symbol interference over a 2.5 Gbit/s data delivery. Based on this thesis analysis, OCS simulation of POF showed the most reliable power penalty performance and receiver sensitivity at 30-m whilst the BI-SMF fiber produced equal observations at 150-m and more. In observing the free space links of delivering the RoF signal, the attenuation on the received signal power for both POF and BI-SMF was insignificant but expected, as the simulation assumed complete and total collimation of the light beams onto the aperture of the photodetector. OCS scheme for mm-wave generation and transport was explored based on the cost effectiveness of using one external modulator compared to other generation schemes that utilised more than one external modulator. OFM scheme was simulated to transport LTE and Wi-Fi signals along with 60 GHz RF band through both SMF and MMF-POF/BI-SMF cables. OFM transport scheme produced the highest attenuation on LTE, Wi-Fi and mm-wave signals carrying 100 Mbit/s data as simulated POF lengths increased. The best performance POF length was observed at 10-m. The application of offset launch technique at the coupling of SMF and POF showed insignificant improvement on signal bandwidth. The free space OFM transmission also demonstrated negligible change to the received signal power. This reinforces the attributes of deploying OWC system in an in-door environment. In other investigation, the simulated successful delivery of mm-wave signal using RHD scheme modulated and transported 10 Gbit/s data signal over POF and BI-SMF cables. Additional observed unrecorded result also showed BI-SMF cable maintained a 2% reduction of received power for 450-m fiber cable from 150-m. The attributes to RHD includes its low operating power system application and delivery of localised 60 GHz signal for uplink RoF transmission. The conceptualised design of Gigabit data delivery for indoor customer applications either through POF or BI-SMF cable, transporting various wireless channels has been presented in this thesis for the design of a robust next generation Broadband access network to reinforce the fiber-inside-the-home (FiTH) deployment.

[pt] O uso de amplificadores a fibra dopada, principalmente o amplificador a fibra dopada com érbio (EDFA), permitiram um grande avanço no desenvolvimento das comunicações ópticas e, o uso de ferramentas para caracterizar estes dispositivos é de grande importância. A técnica de reflectometria óptica no domínio da freqüência (OFDR), é bastante eficiente por se tratar de uma técnica não destrutiva e possibilitar a caracterização do ganho através de medidas de ganho distribuído em fibras dopadas. Neste trabalho foi construído um sistema OFDR sintonizável permitindo medidas em diferentes comprimentos de onda, para caracterização de EDFA, operando na banda C (1530-1565 nm) e L (1565-1610 nm), e também fibras dopadas com túlio, operando na banda S (1450-1530 nm). Graças a estas medidas, foram feitos estudos de diversos esquemas de bombeamento e diferentes topologias visando um melhor entendimento e desempenho dos dispositivos, sempre de forma não destrutiva. / [en] The use of doped fiber amplifiers, especially erbium doped- fiber amplifier (EDFA), has been permitted a great advance in optical communications development, and the use of some tools to characterize these devices has a great importance. The optical frequency domain reflectometry technique (OFDR) is very efficient because it is a non-destructive technique and allows the characterization of the gain through distributed gain measurements. In this work a tunable OFDR system was built permitting to perform measurements in different wavelengths, for characterization in EDFA working in C (1530-1565 nm) and L (1565-1610 nm) bands, as well as Thulium doped fibers operating in S (1450-1530 nm) band. Thanks to these measurements, some different pump schemes studies have been made and also different amplifier topologies to find a best device performance, always in a non-destructive way.

Orientador: Marco Aurélio Cremasco / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-18T08:24:24Z (GMT). No. of bitstreams: 1 Castilho_GuilhermeJosede_D.pdf: 4727634 bytes, checksum: 262e7551887344a4d33739e6ac52ca97 (MD5) Previous issue date: 2011 / Resumo: Stringer (1989) sugeriu que um leito fluidizado gás-sólido pode ser um sistema caótico no qual seu comportamento irregular, entretanto determinístico, é causado por suas propriedades não-lineares. Desde então, surgiu uma nova forma de analisar flutuações de sinais em sistemas fluidizados: a análise não linear de séries temporais, comumente referida como análise de caos. A análise de caos é uma técnica muito utilizada no processamento de sinais em sistemas fluidizados, porém pouco difundida a nível nacional. Este tipo de análise baseia-se na reconstrução de atratores imersos em um espaço de fase e no estudo das propriedades deste atrator. Nesta Tese de Doutorado, avalia-se o comportamento fluidodinâmico em leito fluidizado circulante (LFC) operando sob condição de transporte pneumático diluído utilizando a análise de caos e também outras análises no domínio do tempo, como a distribuição de frequência e desvio médio absoluto. Os sinais avaliados foram obtidos por uma sonda de fibras ópticas, gerando séries temporais de flutuação de sinais elétricos que representam concentração de sólidos. A análise de caos demonstrou que os sistemas estudados apresentam comportamento caótico, por apresentar entropia de Kolmogorov positiva para todas as situações. A vantagem deste tipo de análise em comparação com as ferramentas usuais no domínio do tempo e no domínio da frequência (espectro de Fourier) é que a mesma considera o comportamento não-linear que existe neste tipo de reator multifásico. A partir de seus resultados, pôde-se descrever detalhadamente a fluidodinâmica do LFC, permitindo relacionar os parâmetros encontrados com fenômenos físicos como formação e repartição de clusters, turbulência do gás, interações partícula-partícula e partícula-parede e má alimentação. Tal análise permitiu, inclusive, a identificação de três regimes distintos: diluído, resultante de um escoamento mais complexo devido à turbulência da fase gasosa; concentrado, onde a presença de clusters diminui o caminho médio das partículas e por conseqüência reduz o grau de complexidade do sistema; e um terceiro regime ainda não publicado em trabalhos anteriores, referente às condições extremamente diluídas, onde o aumento do fluxo de sólidos provocou o aumento da complexidade. Neste regime, a fase gasosa predomina e o escoamento é mais previsível quando há presença de poucas partículas. Pretende-se, com esta Tese de Doutorado, incentivar a utilização deste método para, pelo menos, servir como complementação da técnica usualmente utilizada na análise de sinais nesta área de pesquisa, que são os espectros de potência de Fourier / Abstract: Stringer (1989) was the first to suggest that a gas-solid fluidized bed may be a chaotic system, in which the irregular, yet deterministic, behavior is caused by its nonlinear properties. Since then, another way to analyze signals fluctuations in fluidized systems came to light: the nonlinear time series analysis commonly referred to as chaos analysis. It is a technique widely used in the signal analysis in fluidized systems, but not very common at national level. This type of analysis is based on the reconstruction of attractors embedded in a phase space and the study of the properties of this attractor. This Ph.D. Thesis evaluates the fluid dynamic behavior of circulating fluidized bed (CFB) operating under conditions of dilute pneumatic conveying using chaos analysis of chaos and also further analysis in the time domain. The signals obtained were measured by an optical fiber probe which generated time series of fluctuating electrical signals representing solids concentration. The chaos analysis showed that the systems studied exhibit chaotic behavior, by having positive Kolmogorov entropy for all situations. The advantage of this type of analysis compared with the usual tools in the time domain and frequency domain (Fourier spectrum) is that it considers the nonlinear behavior that exists in this type of multiphase reactor. From their results, it was possible to describe in detail the fluid dynamics of the CFB, allowing correlating the parameters found with physical phenomena such as cluster formation and breakdown, the gas turbulence, particle-particle and particle-wall interactions and feed maldistribution. This analysis has led to the identification of three distinct regimes: diluted, resulted from a more complex flow due to turbulence of the gas phase; concentrated, where the presence of clusters decreases the average path length of particles and consequently reduces the complexity of the system; and a third regime not yet published in previous works, regarding the extremely dilute conditions, where the increased flow of solids caused the increase in complexity. In this condition, the gas phase and the predominant flow is more predictable when there is presence of a few particles. With this Ph.D. Thesis, it is intended to encourage the use of this method for at least as a complement to the technique usually used in signal analysis in this research area, that is, the Fourier power spectra / Doutorado / Engenharia de Processos / Doutor em Engenharia Química

This work aims to implement 3D microstructures that generate light with orbital angular momentum towards applications in Biophotonics. Over the past few decades, 3D printing has established itself as the most versatile technology with effortless adaptability. Parallel to this, the concept of miniaturiza tion has seen tremendous growth irrespective of the field and has become an estab lished trend motivated by the need for compact, portable and multi-function devices. Therefore, when these two concepts get together, i.e., 3D printing of miniaturized objects, it could lead to an exciting path with endless opportunities. When it comes to optics, miniaturized 3D printing offers the potential to create compact optical micro-systems and exhibits a way to manufacture freeform µ-optics. In particular, two-photon lithography (TPL) is a cutting edge 3D printing technology that has re cently demonstrated groundbreaking solutions for optics as it offers high resolution with a great degree of flexibility. With a TPL 3D printer, it is possible to fabricate complex µ-optical elements and employ them for compelling applications. In recent years, light with orbital angular momentum (OAM), or ”twisted” light, has captured the interests of several researchers due to its inspiring applications. Tra ditionally, to generate OAM beams, one would require bulk, table-top optics, restrict ing their applications to over-the-table setup. An alternative approach of OAM beam generation is through µ-structures over the fiber, as they can open up new opportu nities, especially in Bioscience, and facilitate in-vivo operations. In particular, this probe-like setup can be used for processes such as optical trapping, high-resolution microscopy, etc. Hence, I propose the development of a novel approach with un precedented capabilities for generating OAM beams right from single-mode optical fibers, by transforming its Gaussian-like output beam by using complex 3D printed microstructures. In this document, I will showcase designs and results on generating Bessel beams (both zeroth- and high-order) and high-NA converging beams (with and without OAM) for optical trapping from the fiber. Remarkably, I achieved the first-ever fiber-based high-order Bessel beam generation and the first-ever fiber optical tweezers with OAM.

Nanoscale materials have great applications in many areas. One of these applications is for manufacturing ultra-compact and efficient sensors for chemical and biological molecule detection. Noble metals, such as gold (Au) and silver (Ag), because of their distinguished optical property"localized surface plasmon resonances (LSPRs) that exhibit low loss, are ideal materials to fabricate these nanoscale plasmonic particles or structures. This work addresses the synthesis, characterization, and sensing applications of Au and Ag nanoparticles (NPs). The progress on certain subjects related to our work"NP synthesis, surface functionalization, Au sphere-film structure and two-photon fluorescence"are reviewed in Chapter 1. We also show the calculation results of LSPRs of Au nanosphere suspensions using Mie theory. The measured extinction spectra of Au nanosphere suspensions agree with the calculated results very well. Chapter 2 is a chapter describing the chemical synthesis of a variety of NPs, such as Ag prisms and cubes, Au spheres, rods, and bipyramids. These experiments involved different synthetic mechanisms and methods which enabled us to prepare NPs with desired shapes and optical properties. To put these NPs into application, it is desirable and sometimes necessary to functionalize their surfaces. In Chapter 3, we present the functionalization of Ag cubes with poly(allylamine hydrochloride) (PAH) and poly(allylamine hydrochloride)-dithiocarbamate (PAH-DTC), which follows our previous work on Au NPs. The purpose of studying Ag instead of Au is to use the stronger plasmonic enhancement in Ag when applied to two-photon imaging applications. However, we found that PAH-DTC shrank the Ag cubes. We also functionalized the cationic hexadecyltrimethylammonium bromide (CTAB)-stabilized Au NRs with anionic poly(sodium 4-styrenesulfonate) (PSS). Coated with the strong polyelectrolyte PSS, the NRs become more manageable and can be stable for over six months and are easily immobilized onto positively charged substrate. We put PSS-functionalized Au NPs into use and studied their adsorption process onto PAH-coated optical fiber tapers by monitoring the transmission light through the fiber. When the diameter of the fiber taper gets smaller, stronger coupling occurred between transmitted light inside the taper and the Au NPs on the taper surface (cylinder). This coupling resulted in a loss of the guided light at the plasmon resonance wavelength of the NPs. By monitoring this loss, we can study the adsorption rate of Au NPs onto the fiber. In Chapter 4, we used Au nanospheres to study the adsorption rate on substrates with different curvatures. We also established a theoretical model to explain this phenomenon for cylindrical surface as well as planar and spherical surfaces. Our results fit well with the theory, which predicts that particle adsorption rates depend strongly on surface geometry, and can exceed the planar surface deposition rate by over two orders of magnitude when the diffusion length of the particle is large compared to the surface curvature. In Chapter 5, we studied the optical properties of Au nanospheres separated from a thick Au film by a polyelectrolyte multilayer (PEM) film assembled from PAH and PSS under specific pH condition. The PEM film undergoes swelling and shrinking when the environmental pH is changed as a result of charging and discharging of the polyelectrolytes. Therefore, the PEM film provides an efficient means to tune the distance between Au spheres and Au film. The extinction peak blue-shifted as much as 100 nm when the pH of the water changed from pH 10 to pH 3 for 100 nm diameter Au spheres on a PEM film assembled at pH 9.5. Our preliminary estimates that the gap between sphere and surface can be as small as a few nm even though the film itself is tens of nm thick when it is not constrained by Au spheres. We studied two-photon excitation fluorescence (TPEF) from Ag triangles in Chapter 6. The triangles were fabricated by nanosphere lithography, which used convective self-assembly to make the nanosphere mask. The LSPRs of the nanotriangles were tuned to be in the 800--900 nm range to match with the Ti:Sapphire pulse laser at 880 nm. We found that certain spots on the fluorescence images gave rise to larger fluorescence intensity than rest of the area. SEM imaging reveals that the unusually bright spots seen on the surface were related to regions where the triangles transformed to spherical particles. The larger intensity is tentatively ascribed to the plasmon resonance of those spherical particles in ~400 nm range. / Ph. D.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Current ground-based tracking systems at the DoD test and training ranges require transmission of a variety of signals from rotating platform to fixed control and process center. Implementation of commercial off the shelf (COTS) solution for transmitting high-speed, multiple-channel data signals over a rotational platform prompt the development of an advanced electro-optic hybrid rotating-to-fixed information transmission technology. Based on current demand, an Air Force-sponsored Small Business Innovative Research (SBIR) contract has been awarded to Physical Optics Corporation (POC) to modify existing tracking mounts with a unique electro-optic hybrid rotary joint (EOHRJ). The EOHRJ under current development is expected to provide the following features: 1) include a specially designed electrical slip-ring, which is able to accommodate hundreds of transmission channels, including electrical power, control, feedback, and low-speed data signals; 2) include an optical fiber slip-ring which, by incorporating with electrical time division mulitplexing (TDM) and optical wavelength division multiplexing (WDM) technologies, is able to provide multiple channel, high data rate (over gigabits per second), and bi-directional signal transmission; and 3) is designed to be reliable for harsh environmental operation, adaptive to stringent size requirement, and accommodating to existing electrical and mechanical interfaces. Besides the military use, other possible commercial applications include on board monitoring of satellite spinners, surveillance systems, instrumentation and multi spectral vision systems, emergency/medical instruments, remote sensing, and robotics.

Optical imaging techniques have improved much over the last fifty years since the invention of the laser. With a high brightness source many imaging applications which were once inaccessible to researchers have now become a reality. Among these techniques, the most beneficial one is the use of lasers for both wide-field and confocal imaging systems. The aim of this study was to design a laser imaging system based on the concept of laser scanning confocal microscopy. Specifically the optical system was based on optical fibers allowing the user to image remote areas such as the inner surface of rifled gun barrels and/or pipes with a high degree of precision (+/- 0.01 mm). In order to build such a system, initially the theoretical foundation for a confocal as well as a wide-field imaging system was analyzed. Using this basis a free-space optical confocal system was built and analyzed. The measurements support the fact that both the objective numerical aperture and pinhole size play an important role in the radial and axial resolution of the system as well as the quality of the images obtained. To begin construction of a confocal, optical-fiber based imaging system first an all fiber wide-field imaging system was designed and tested at a working wavelength of 1550 nm. Then an all fiber confocal system was designed at a working wavelength of 808 nm. In both cases results showed that while lateral resolution was adequate, axial resolution suffered since it was found that the design of the optical system needs to take into account under-filling of the objective lens, a result common with the use of laser beams whose divergence is not at all like that of a point source. The work done here will aid technology that will be used in the elimination process of faulty rifling fabrication in defense industry. The reason why the confocal technique is preferred to the conventional wide-field one is the need for better resolution in all directions. Theoretical concepts and mathematical background are discussed as well as the experimental results and the practical advantages of such a system.