Os objetivos desta tese são: o estudo e aprimoramento dos diferentes parâmetros geométricos e de processo de fabricação de guias de onda ARROW (Anti-Resonant Reflecting Optical Waveguides), visando reduzir as perdas por propagação; e o projeto, fabricação e caracterização de sensores óptico integrados utilizando os processos aprimorados. Os parâmetros estudados foram: os materiais utilizados nas camadas antirresonantes, as espessuras destas camadas, a profundidade de corrosão para definição do rib e a rugosidade nas paredes laterais, que considera-se o parâmetro mais crítico no que diz respeito às perdas por propagação obtidas com o processo de fabricação utilizado neste trabalho. Os materiais utilizados na fabricação dos guias de onda ARROW sobre substrato de silício foram filmes de oxinitreto de silício (SiOxNy) depositados por PECVD à temperatura de 320°C, filmes de SiO2 crescidos em forno de oxidação em ambiente úmido a 1200°C e filmes de TiOxNy depositados pela técnica de Magnetron Sputtering Reativo. A definição das paredes laterais dessas estruturas foi feita através da Corrosão por Plasma Reativo (RIE) e técnicas fotolitográficas convencionais. Para o aprimoramento dos processos, as técnicas de caracterização utilizadas foram: medidas de perdas por propagação, utilizando a técnica de vista superior e a análise modal dos guias de onda. A principal contribuição deste trabalho foi a proposição de um processo de fabricação alternativo, onde pedestais são utilizados para a definição das paredes laterais antes da deposição do núcleo dos guias de onda. Este processo permitiu a redução significativa das perdas e o corte dos modos superiores para guias com larguras menores ou iguais a 6 µm. Finalmente, com os guias e os processos aperfeiçoados foram fabricados dois diferentes tipos de sensores ópticos: sensores refratométricos baseados em interferômetro de Mach-Zehnder (IMZ) e sensores de umidade baseados em absorção utilizando o polímero polipirrol (PPy). A caracterização dos sensores baseados em IMZ permitiu concluir que, embora se tenha observado uma resposta do sensor em termos de variação da potência na saída do dispositivo com a variação do índice de refração, esta variação possivelmente está sendo influenciada pela interferência multimodo resultante de limitações do processo de fabricação, o que reduz significativamente a sensibilidade com relação a valores projetados. Os sensores de umidade apresentaram uma variação significativa da potência de saída para umidades relativas ao redor de 70%, permitindo sua utilização em diferentes aplicações, como na indústria alimentícia e no monitoramento da qualidade do ar. / The main goals of this thesis are: the study and improvement of different geometrical and fabrication process parameters of Anti-Resonant Reflecting Optical Waveguides (ARROWs), aiming at reducing the propagation losses; and the design, fabrication and characterization of integrated optics sensors using the improved processes. The studied parameters were: the materials used as anti-resonant layers, the thickness of these layers, the rib height and the sidewall roughness (SWR), which is considered the most critical parameter with respect to propagation losses in the fabrication process used in this work. The materials used in the fabrication of ARROW waveguides over silicon substrate were silicon oxynitride (SiOxNy) films deposited by PECVD at 320°C, SiO2 films, thermally grown at 1200°C and TiOxNy films deposited by the reactive magnetron sputtering technique. The definition of the sidewalls of these waveguides was performed by Reactive Ion Etching (RIE) and conventional photolithographic techniques. The characterization techniques used were: propagation loss measurements, using the top view technique and modal analysis. The main contribution of this work was the proposition of an alternative fabrication process where pedestals are used in order to define the sidewalls before deposition of the core of the ARROW waveguides. This process allowed significant reduction of losses and cutoff of higher modes at widths of 6 µm. Finally, with the waveguides and improved processes two different types of optical sensors were fabricated: refractometric sensors based on Mach-Zehnder interferometer (IMZ) and humidity sensors based on evanescent field absorption using polypyrrole polymer (PPy). The characterization results of IMZ based sensors showed that, although a sensor response has been observed in terms of change of output power with variation of the external medium\'s refractive index, this variation is possibly being influenced by multimode interference resulting from limitations in the fabrication process. This significantly reduces the sensitivity with respect to designed values. The humidity sensors show a significant variation in output power for relative humidity values around 70%, allowing its use in different applications, such as in food industry and in air quality monitoring.

O presente trabalho apresenta a produção e a investigação das propriedades ópticas de guias de onda vítreos baseados no sistema PbO-GeO2, codopados com íons de érbio de itérbio e contendo nanopartículas metálicas de ouro e prata, para aplicações como dispositivos fotônicos na terceira janela de telecomunicações (1530 nm). Os guias de onda foram obtidos por meio de processos convencionais utilizados em microeletrônica usando a técnica RF Magnetron Sputtering para deposição do material sobre uma estrutura do tipo PEDESTAL. Os primeiros guias produzidos apresentaram irregularidades laterais próximas ao núcleo que contribuíram para o aumento das perdas. Mudanças no processo de fabricação como a diminuição da espessura da máscara de cromo usada para a corrosão do SiO2, etapa adicional para a corrosão e a diminuição da espessura do guia de onda proporcionaram redução das perdas por propagação e aumento do ganho óptico em ~50% estimado em 6,0 dB/cm, em 1530 nm, para um guia de onda de 80 µm de largura. Entretanto, as dificuldades para medir guias com menores larguras levaram-nos a produzir guia de onda PEDESTAL utilizando SiO2 como máscara de corrosão do silício que permitiram redução significativa das irregularidades lateral; neste caso foi possível medir a perda e o ganho em guias com largura de até 1 µm. Acrescenta-se que guias de 6 µm tiveram aumento do ganho em 50% na presença de nanopartículas de ouro, atingindo 7,5 dB/cm para potência de bombeamento de 60 mW, portanto inferior à utilizada para o caso do guia sem nanopartículas de ouro, cuja saturação do ganho ocorreu em 100 mW. Guias com nanopartículas de prata foram também produzidos, obtendo-se ganho máximo de 4,0 dB/cm para um guia de 80 µm. Os resultados obtidos nos guias de onda PbO-GeO2 codopados com Er3+ e Yb3+ são promissores e mostram possibilidade de aplicação dos guias de onda como amplificadores ópticos na terceira janela de telecomunicações. / This work presents the production and investigation of optical properties of erbium and ytterbium ions codoped PbO-GeO2 waveguides, containing metallic nanoparticles (NPs), for applications as photonic devices in the third window Telecommunications (1530 nm). The waveguides were obtained by microelectronics conventional processes and by RF Magnetron Sputtering technique using a pedestal type structure. The first pedestal waveguides presented irregulaties, in the lateral region, that contributed to the propagations losses enhancement. Changes in the fabrication process, as the decrease of the chromium used for SiO2 corrosion, additional step for the etching and decrease of the waveguide thickness provided reduction of the propagation losses and enhancement of the optical gain of about 50%; so we obtained 6.0 dB/ cm, at 1530 nm, for 80 µm waveguide width. The difficulty to measure waveguides with smaller width lead us to develop PEDESTAL waveguides using SiO2 as silicon mask for corrosion enabled the decrease of the roughness nearby the core. In this case it was possible to measure propagation losses and gain for waveguides width of 1 µm. It was obtained enhancement of 50 % for the waveguides with 6 µm width in the presence of gold NPs and the result was 7.5 dB/cm at 60 mW pumping power; for the case of the waveguide without gold NPs gain saturation occurred at 100 mW. Waveguides with silver NPs were also produced and the maximum gain was of 4.0 dB/cm for 80 µm. These results show the possibility of using Er3+and Yb3+ codoped PbO-GeO2 pedestal type waveguides as optical amplifiers in the third telecommunications window.

Orientador: Hugo Enrique Hernández Figueroa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-19T00:51:23Z (GMT). No. of bitstreams: 1 Pasetto_TadeuPires_M.pdf: 7097480 bytes, checksum: a432943fd52e29cfe68bd7e99f0b14f7 (MD5) Previous issue date: 2011 / Resumo: Este trabalho apresenta o estudo, o projeto e a caracterização de estruturas de cristal fotônico bidimensionais na faixa de micro-ondas para arranjos cilíndricos dielétricos em simetria triangular e quadrada, com e sem curvas, na faixa de 2 a 4 GHz. A escolha dos arranjos foi feita baseando-se no cálculo do diagrama de bandas e dos modos guiados no cristal após ser removida uma linha de elementos. Foram projetadas estruturas casadoras que tornaram possível caracterizar esses guias de onda com o auxílio de um analisador de rede. As montagens das estruturas de cilindros dielétricos com as placas metálicas e as estruturas casadoras, foram simulada no programa comercial CST Microwave Studio 2010®. Uma vez construída e caracterizada as estruturas, os resultados foram analisados e comparados. A banda passante apresentou um deslocamento em frequência, coerente com os erros da montagem construída / Abstract: This work presents the study, design and measurements of microwave twodimensional photonic crystal waveguides, for square and triangular arrays of dielectric roads, with and without bend, in the 2-4 GHz band. The choice of the arrays was based on the calculated band diagrams of the crystals and guided modes for the waveguide which arises when a line of roads is removed from the crystal structure. Matching structures were projected to enable the corresponding measurements using a network analyzer. The entire structure: dielectric roads, metallic plates and matching structures, was simulated using the CST Microwave Studio 2010®, constructed and measured, and the results were analyzed and compared. The measured guided band frequency exhibits a shift when compared with the simulated one, consistent with the imprecision of the setup / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Orientador: Hugo Enrique Hernandez Figueroa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-19T08:38:08Z (GMT). No. of bitstreams: 1 Silva_AlexandreManoelPereiraAlvesda_D.pdf: 7013947 bytes, checksum: c23d3c786fbf204c86a3e94bd5da9bd2 (MD5) Previous issue date: 2011 / Resumo: O projeto e o estudo de lentes plasmônicas operando nos comprimentos de onda de 650nm e 1550nm são, aqui, apresentados. Uma lente desse tipo permite que a luz proveniente de um guia de ondas micrométrico, por exemplo, uma fibra óptica, seja acoplada em estruturas como guias de ondas nanométricos ou nanocavidades ressonantes, a distâncias curtas, reduzindo, sobremaneira, a área necessária somente para acoplamento. São analisadas, também, as condições do foco para que haja um acoplamento eficiente de luz aos guias de ondas nanométricos. O foco conformado por essa lente localiza-se a distâncias da ordem de um comprimento de onda. A lente plasmônica recebe essa denominação por utilizar os polaritons de plasmons de superfície como meio de transportar a luz pela lente. Os polaritons de plasmons de superfície são ondas eletromagnéticas superficiais que se propagam na interface entre um meio dielétrico e um meio condutor. Eles permitem que haja modos propagantes em guias de ondas com dimensões muito inferiores ao limite da difração, como em fendas nanométricas recortadas em um filme metálico. é possível controlar a constante de propagação e, por conseguinte, a variação de fase dentro de uma fenda desse tipo, controlando a espessura da mesma. Dispondo várias fendas ao longo de um filme metálico, é possível projetar uma lente plana pelo controle da modulação da fase de saída dessas diversas fendas. Esse comportamento é semelhante ao de um arranjo de antenas, porém, o foco é formado na região de campo próximo. Após uma varredura dos parâmetros construtivos da lente, foi possível obter uma lente de perfil plano que permita o acoplamento eficiente entre guias de ondas com diferenças de dimensão de mais de uma ordem de grandeza dentro de distâncias da ordem de um comprimento de onda. Uma proposta de lente posicionada na ponta de uma fibra óptica é sugerida, a qual permite o acoplamento ou excitação de uma ou mais estruturas ópticas ao mesmo tempo / Abstract: The project and the study of plasmonic lenses operating in the wavelengths of 650nm and 1550nm are presented. Such a lens allows the light coupling from a microsized waveguide, for instance, an optical fiber, to nanosized structures such as nano-waveguides or nano-cavities, within short distances, reducing the amount of area used just for coupling. It is also analyzed the focus conditions for efficient coupling to dielectric nano-waveguides. The lens focus is placed at distances about one wavelength apart. This lens is called plasmonic lens because the excitation of surface plasmon polaritons allows the propagation of light through it. Surface plasmon polaritons are electromagnetic surface waves that propagate along the interface of a dielectric media and a conductor. They allow the formation of propagating modes within waveguides bellow the diffraction limit, such as nano-slits cut into a metallic film. The propagation constant therefore, the phase variation inside such a slit, is controlled by its width. Then, placing several slits along the metallic film, it is possible to design a plane lens by designing the phase modulation of several slits cut into a metallic film. This behavior is similar to an antenna array, however, the focus is formed within the nearfield zone. After some variations on the design parameters, it is obtained a plane lens showing an efficient coupling between different dimensions dielectric waveguides within one wavelength distance from the lens. A lens configuration positioned on a optical fiber is proposed. This configuration allows coupling or excitation of one or more optical structures at the same time / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

[pt] Neste trabalho são analisados os campos modais em guias circulares contendo em seu eixo um carregamento cilíndrico dielétrico uniforme ou corrugado, identificando propriedades destes campos úteis a aplicações no projeto de ressoadores, filtros e alimentadores. Com o objetivo de apresentar uma aplicação da análise dos guias circulares com carregamento dielétrico, é feita a análise de um ressoador dielétrico cilíndrico apresentando- se sua carta modal relacionando suas freqüências de ressonância com o carregamento dielétrico. / [en] In this work the modal fields for circular waveguides with uniform or corrugated dieletric loads are analysed, and useful properties of these fields to applications such as ressonators, filters and antenna feeders are ecamined. As an application of the analysis of dieletric loaded circular waveguides, an algorithm is developed for the determination of ressonant frequencies of dieletric loaded ressonators, and the modal chart, relating ressonant frequencies to ressonator dimensions, is evaluated.

[pt] No presente trabalho, diversos métodos de análise são aplicados ao problema de íris em guias de onda. É feita, inicialmente, uma análise da teoria de pequenas aberturas. Uma verificação, através de comparação de resultados teóricos com experimentais, determina a faixa de validade e precisão da teoria. A seguir, aplica-se o método dos momentos, em particular para íris circulares em guias circulares e íris retangulares em guias retangulares. Para o caso da íris retangular em guia retangular, problemas de convergência relativa e séries lentas, típicos do método dos momentos, são contornados pela escolha adequada das funções de base e pela transformação de séries auxiliares de correção. Resultados experimentais mostram boa concordância com valores teóricos, para diversos valores de freqüência e dimensões de íris considerados. / [en] In this work, different methods are applied to iris - type discontinuity problems in waveguides. At first, the diffraction theory by small holes is considered. Theoretical results are compared with experimental ones and the accuracy and application range of the theory are verified. Further, the moment method is applied particularly to circular irises in circular waveguides and retangular irises in retangular waveguides. In the case of retangular irises in retangular waveguides, an acceleration procedure besides an special kind of basis functions is used to circumvent problems associated with relative convergence problem and slow convergent series. Experimental results are compared with theoretical ones and good accuracy is achieved for different frequencies and irises dimensions.

The varied properties of Silicon Carbide (SiC) are helping to launch the material into many new applications, particularly in the field of novel semiconductor devices. In this work, the cubic form of SiC is of interest as a basis for developing integrated optical components. Here, the formation of a suitable SiO2 buried cladding layer has been achieved by high dose oxygen ion implantation. This layer is necessary for the optical confinement of propagating light, and hence optical waveguide fabrication. Results have shown that optical propagation losses of the order of 20 dB/cm are obtainable. Much of this loss can be attributed to mode leakage and volume scattering. Mode leakage is a function of the effective oxide thickness, and volume scattering related to the surface layer damage. These parameters have been shown to be controllable and so suggests that further reduction in the waveguide loss is feasible. Analysis of the layer growth mechanism by RBS, XTEM and XPS proves that SiO2 is formed, and that the extent of formation depends on implant dose and temperature. The excess carbon generated is believed to exit the oxide layer by a number of varying mechanisms. The result of this appears to be a number of stable Si-C-O intermediaries that form regions to either depth extreme of the SiO2 layer. Early furnace tests suggest a need to anneal at temperatures approaching the melting point of the silicon substrate, and that the quality of the virgin material is crutial in controlling the resulting oxide growth.

Advances in photonic materials are critical to the progress of photonic devices and optical systems. Even though a variety of materials, e.g. semiconductors, oxide based glasses, and polymers exist which are being used for numerous applications, there is a growing need to develop and find new materials in order to push the limits we are bound by with conventional materials, in pursuit of higher performance, higher levels of integration and lower cost. In this realm, new material development has had a considerable impact, as it is the material properties (optical, thermal, mechanical, electrical, ...) in addition to their processing and compatibilities with standard processes that enable us the creation of entirely new devices or improve the performance of currently available optical devices. In this dissertation, I will demonstrate the application of two new materials for novel photonic components. In the first part of the dissertation, I discuss how a hybrid approach to the silicon photonics platform can reduce thermal sensitivity using sol-gel based inorganic-organic hybrid materials. The approach is to design the optical waveguide so that it maintains its performance in a passive manner in response to environmental temperature variations and, thus, does not need external temperature control resulting in reduced electrical power consumption. Sol-gel materials are well-known, but they haven’t been exploited like polymers and titanium dioxide to be cladding layers to enable athermal silicon waveguides. In this work I show their advantages with respect to previous materials that were employed for athermal microring resonators. I studied the thermal curing parameters of the sol-gel and its effect on thermal wavelength shift of the microring resonance. With this method, I was able to achieve a thermal shift down to -6.8 pm/°C for transverse electric (TE) polarization, as well as thermal shifts below 1 pm/°C for transverse magnetic (TM) polarization in the C band under different curing conditions, all while preserving high Q resonator performance. The results and methodology described opens a new and more manufacturable approach to attain athermal silicon photonic devices. In the second part of the dissertation, I introduced a new, sulfur rich, low cost copolymer material developed by our colleagues in the chemistry department. This copolymer has unique properties that conventional optical polymers, such as polymethylmethacrylate and polycarbonate, lack, while also having low cost. I demonstrated that these polymers have very good processing capabilities, being easily moldable to make free space optical elements and solution processable for use in integrated optics. I studied their linear and nonlinear optical properties, finding them to possess high refractive indices and transparencies over a wide range from 550 nm to 6 µm, except for a small region of absorption from 3-3.3 µm. Finally, I demonstrated that these new copolymers are suitable and economical alternative for shortwave and midwave infrared optics (SWIR and MWIR, respectively).

Chalcogenide glasses are highly nonlinear optical materials which can be used for fabricating active and passive photonic devices. This thesis work deals with the fabrication of buried, three dimensional, channel waveguides in chalcogenide glasses, using ultrafast laser inscription technique. The femtosecond laser pulses are focused into rare earth ions doped and undoped chalcogenide glasses, few hundred microns below from the surface to modify the physical properties such as refractive index, density, etc. These changes are made use in the fabrication of active and passive photonic waveguides which have applications in integrated optics. The first chapter provides an introduction to the fundamental aspects of femtosecond laser inscription, laser interaction with matter and chalcogenide glasses for photonic applications. The advantages and applications of chalcogenide glasses are also described. Motivation and overview of the present thesis work have been discussed at the end. The methods of chalcogenide glass preparation, waveguide fabrication and characterization of the glasses investigated are described in the second chapter. Also, the details of the experiments undertaken, namely, loss (passive insertion loss) and gain measurements (active) and nanoindentation studies are outlined. Chapter three presents a study on the effect of net fluence on waveguide formation. A heat diffusion model has been used to solve the waveguide cross-section. The waveguide formation in GeGaS chalcogenide glasses using the ultrafast laser, has been analyzed in the light of a finite element thermal diffusion model. The relation between the net fluence and waveguide cross section diameter has been verified using the experimentally measured properties and theoretically predicted values. Chapter four presents a study on waveguide fabrication on Er doped Chalcogenide glass. The active and passive characterization is done and the optimal waveguide fabrication parameters are given, along with gain properties for Er doped GeGaS glass. A C-band waveguide amplifier has been demonstrated on Chalcogenide glasses using ultrafast laser inscription technique. A study on the mechanical properties of the waveguide, undertaken using the nanoindentation technique, is presented in the fifth chapter. This work brings out the close relation between the change in mechanical properties such as elastic modulus and hardness of the material under the irradiation of ultrafast laser after the waveguide formation. Also, a threshold value of the modulus and hardness for characterizing the modes of the waveguide is suggested. Finally, the chapter six provides a summary of work undertaken and also discusses the future work to be carried out.

We explore a new laboratory technique in the field of urinalysis promising a combination of speed and selectivity in support of urinary tract infection diagnosis. Laboratory experimentation demonstrates long range surface plasmon polaritons (LRSPP) waveguides as a useful biosensor to selectively detect gram negative bacteria or gram positive bacteria in human urine. The biosensor can detect bacteria at concentration of 105 CFU/ml, the internationally recommended threshold for diagnostic of urinary tract infection (UTI). Using a negative control solution at bacterial concentration 1000x higher than the targeted bacteria in urine with a weak concentration of constituents, the power ratio between the negative control signals to the target bacteria signal is measured to be 5.4. Thus we report a conclusive demonstration of the LRSPP waveguide biosensor selectivity to the gram of bacteria in human urine. In addition, the biosensor may prove useful as an alternative urinalysis test method to determine the urine specific gravity, to estimate proteinuria, and to detect biofilm formation on surfaces.