Thesis (Ph. D.)--Carleton University, 1988. / Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Michigan, 1954. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 127-130).

Thesis (Ph. D.)--University of Idaho, 2005. / Also available online in PDF format Abstract. "October 2005." Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 185-203).

CAPES / Neste trabalho são estudadas configurações de amplificadores híbridos compostos por amplificador Raman em cascata com EDFA, a serem utilizados na expansão da capacidade de sistemas de comunicações óticas utilizando WDM. Foi realizado, mediante simulação em um pacote comercial, um estudo do desempenho de diferentes esquemas desses amplificadores híbridos Raman+EDFA, em termos do ganho global, ondulação (ripple) e figura de ruído. A flexibilidade do perfil espectral do amplificador Raman pode ser combinada com a alta capacidade de potência de saída do EDFA para obter aplicações de amplificadores híbridos banda larga. Este trabalho aplica uma nova técnica de otimização de amplificador híbrido Raman+EDFA para aplicações WDM. É utilizado o modelo de aproximação analítica com menor tempo de cálculo, para determinar o perfil espectral do estágio de amplificação Raman. A otimização foi realizada para uma configuração de amplificador híbrido Raman+EDFA utilizando uma fibra compensadora de dispersão (DCF) com múltiplos lasers de bombeamento no estágio Raman. A otimização foi focada no ganho global e na ondulação do amplificador híbrido resultante. Os resultados demonstraram que o amplificador híbrido Raman+EDFA com reciclagem de bombeamento residual Raman, combinado com uma seleção apropriada de potências e comprimentos de onda dos lasers de bombeamento Raman, possibilita a obtenção de amplificadores híbridos banda larga com maior eficiência de conversão de potência, ganho alto e plano. Os resultados também mostraram ganhos médios maiores, menor ondulação e largura de banda maior que os encontrados na literatura. Tais resultados podem contribuir para um melhor conhecimento das vantagens e desvantagens de amplificadores híbridos utilizados em enlaces óticos. / In this work different configurations of hybrid amplifiers are studied, made by a Raman amplifier followed by an EDFA. Such amplifiers can be used to increase the transmission capacity in WDM based optical communication systems. The performance of different hybrid EDFA+Raman amplifiers is obtained using commercial software. Their performance is analyzed in terms of the global gain, ripple and noise figure. The design and development of new configurations of fiber amplifiers, such as Raman and erbium-doped fiber amplifiers operating in a combined system that allows recycling pump power, contributes to minimize the energy consumption of the entire transmission system. Raman amplifiers can be used along with the EDFA high output power capacity to add spectral shaping flexibility for broadband applications. This work applies a new technique to optimize Raman+EDFA hybrid amplifiers for WDM applications. It uses an analytical approximated model to determine the spectral shaping of the Raman gain stage avoiding the time-consuming process of spectral profile optimization. The optimization has been carried out on a hybrid Raman+EDFA amplifier configuration, using dispersion compensating fiber with multiple pump lasers in the Raman amplification stage. The optimization has focused on the global gain and its ripple factor for the hybrid amplifier. Results demonstrated that the Raman+EDFA hybrid amplifier under recycling residual Raman pump, allied with the proper selection of pump wavelengths and powers, enables the construction of broadband amplifiers with enhanced power conversion efficiency and high and flat gains. Results also show average high gain, lower ripple, and higher bandwidth than those found in the literature. Such results can contribute to a better knowledge of the advantages and drawbacks of hybrid Raman/EDFA amplifiers in optical links.

O efeito Raman ressonante do complexo (NH4)4Mo2Cl8.NH4Cl.H2O, contendo o íon Mo2Cl84-, foi estudado tanto na temperatura ambiente como na de nitrogênio líquido. Com base nos resultados obtidos mostra-se que a explicação previamente oferecida por outros autores para o aparecimento de ressonância com excitação em 568,2 nm não é correta. É sugerida uma explicação diferente para este comportamento baseada nos espectros Raman e de absorção. A transferência de elétron fotoestimulada no íon complexo (NH3)5RuII-pz-CuII foi comprovada através do estudo do efeito Raman ressonante. Com base nos espectros Raman obtidos em condições de ressonância e também nas medidas de polarização, o estado eletrônico excitado envolvido foi caraterizado. Os perfis de excitação para v1 e 2vl do íon RuO42- em solução aquosa foram obtidos usando diversas radiações excitantes. Os perfis mostraram uma desintensificação das intensidades Raman pré-ressonantes na região da transição interna do íon. O efeito foi interpretado usando o tratamento proposto por Stein e col. para o efeito Raman anti-ressonante. / The Raman resonance effect of the complex (NH4)4Mo2Cl8.NH4Cl.H2O, containing the Mo2Cl84- ion, was investigated at both room and liquid nitrogen temperatures. On basis of the obtained results it is shown that the previous explanation given by others authors for the resonance observed with 568.2 nm excitation is not a correct one. A different explanation for this behaviour is suggested, based on the Raman and absorption spectra. The photostimulated electron transfer in the complex ion (NH3)5RuII-pz-CuII was confirmed trough the investigation of its Raman ressonance effect. The Raman ressonance spectra and the polarization measurements had enabled the characterization of the electronic excited state involved in the transition. The excitation profiles of v1 and 2v1 of the RuO42- ion in aqueous solution were obtained using several exciting radiations. The profiles present a de-enhancement of the pre-resonant Raman intensities in the region of the ion internal transition. This effect was interpreted using the treatment proposed by Stein et al. for the anti-resonance Raman effect.

The need to exploit the large fibre bandwidth and increase the reach has seen the application of the Raman fibre amplifier (RFA) become indispensable in modern light wave systems. The success and resilience of RFAs in optical communication is deeply rooted in their unique optical properties and new technologies which have allowed the amplifier to come of age. However, the full potential of RFAs in optical communication and other applications are yet to be realized. More so are its polarization properties which still remain largely unexploited and have not been fully understood. In this work, fundamental issues regarding distributed RFA have been investigated with the aim of acquiring a better understanding of the amplifier polarization characteristics which have potential applications. In particular the effects of polarization mode dispersion (PMD) and polarization dependent loss (PDL) have been demonstrated both by simulation and experiment. The possibility of Raman polarization pulling in single mode fibres (SMFs) has also been addressed. Polarization sensitivity of RFA has been known for a long time but the clear manifestation of it has become evident in the advent of modern low PMD fibre. Unlike EDFAs which make use of special doped fibre, RFAs require no special fibre for operation. Besides, RFA uses a very long length of fibre and as such the fibre polarization characteristics come into play during amplification. In the demonstrations presented in this thesis a fibre of PMD coefficient < 0.05 pskm-1/2 was regarded as low PMD fibre while one having coefficient ≥ 0.05 pskm-1/2 was categorized to have high PMD unless otherwise stated. Several experiments were performed to evaluate the RFA gain characteristics with respect to fibre PMD and the system performance in the presence of noise emanating from amplified spontaneous emission (ASE). Analysis of Raman gain statistics was done for fibres of low and high PMD coefficients. The statistics of PDG and on-off gain were eventually used to demonstrate the extraction of PMD coefficients of fibres between 0.01- 0.1 pskm-1/2 using a forward pumping configuration. It was found that, at increasing pump power a linear relationship exists between forward and backward signal gain on a dB scale. The interaction of PDL and Raman PDG in the presence of PMD were observed at very fundamental level. It was found the presence of PDL serves to reduce the available on-off gain. It was also established that the presence of PMD mediates the interaction between PDG/PDL. When PMD is high it reduces PDG but the presence of PDL introduces a wavelength dependent gain tilting for WDM channels. Further analysis revealed that signal polarization is influenced by the pump SOP due to the pulling effect which is present even at moderate pump power.

Vibrational imaging approaches including Raman microscopy and IR-absorption micro-spectroscopy can provide rich chemical information about biological samples. This dissertation contributes to improve the capabilities of vibrational microscopy in three aspects each with corresponding biological applications. First, along the line of combining electronic resonant effect with stimulated Raman scattering (SRS), we studied the spectroscopic characteristics for on-resonant SRS case and demonstrated the utility of electronic pre-resonant SRS on super-multiplexed imaging for live cells and tissue sections. Second, we provided a new light-matter interaction as a hybrid technique of Raman and fluorescence, called stimulated Raman excited fluorescence (SREF), bringing the long-sought-after goal of detecting single-molecule Raman scattering without plasmonic enhancement into view. Coupling SREF with vibrational sensing, local electric field and hydrogen-bonding environment can thus be visualized in situ. Third, we brought small vibrational probes into mid-infrared imaging for the goal of rich-information-content, high-throughput metabolic imaging. Chapter 1 introduces some basis of Raman scattering, and provides an overview of state-of-art SRS microscopy. Chapter 2 explores on the rigorous electronic resonant region with SRS (er-SRS) through suppression of electronic background and subsequent retrieval of vibrational peaks. In agreement with theoretical prediction, changing of vibrational band shapes from normal Lorentzian, through dispersive shapes, to inverted Lorentzian is observed when approaching electronic resonance. As large as 10-23 cm2 of resonance Raman cross section is estimated in er-SRS. In Chapter 3, a new light-matter interaction called stimulated Raman excited fluorescence (SREF) is studied. Through stimulated Raman pumping to an intermediate vibrational eigenstate followed by an upconversion to an electronic fluorescent state, SREF encodes vibrational resonance into the excitation spectrum of fluorescence emission. By leveraging superb sensitivity of SREF, we achieved all-far-field single-molecule Raman spectroscopy and imaging without plasmonic enhancement. Chapter 4 details the development of SREF into a novel water-sensing tool, by coupling with vibrational solvatochromism of environment-sensitive Raman mode. This new technique allows direct visualization on spatially-resolved distribution of water states inside single mammalian cells. Interesting intracellular heterogeneity of water states between nucleus and cytoplasm has been revealed. Chapter 5 demonstrates the utility of epr-SRS in super-multiplexed imaging with either commercial fluorophores in lives cells or our MARS probes on tissue sections. Multiplex protein-based tissue imaging is completed with newly-designed functional MARS dye with up to 12 channels simultaneously. Chapter 6 focus on metabolic imaging by mid-infrared (MIR) microscopy with vibrational probes. Raman scattering microscopy has made a major advance in metabolic imaging utilizing vibrational probes, yet is limited to relatively low throughput. As an alternative solution, MIR microscopy provides significantly higher cross section and exhibits as a rich-information-content, high-throughput technique with recent rapid technical advances. We introduced three types of small vibrational probes as azide, 13C and carbon-deuterium for studying dynamic metabolic activities of protein, lipids and carbohydrates in cells, small organisms and mice for the first time. Two MIR microscopy platforms as Fourier transform infrared (FTIR) absorption microscopy and discrete frequency mid-infrared (DFIR) microscopy were utilized to validate the generality of our vibrational probes and applicability for single-cell metabolic profiling and metabolism study on large-scale tissues.