A fibra óptica apresenta características que favorecem a propagação de sinais eletromagnéticos de um ponto a outro, quando comparada a outros guias de onda. Além disso, pode ser empregada para comunicações de pequena, média e grandes distâncias. Para cada tipo de situação, diferentes tipos de fibras podem ser utilizadas. Em termos de fabricação, o controle do diâmetro absoluto da fibra nas suas duas etapas de fabricação (obtenção da pré-forma e puxamento) é de suma importância para garantir os padrões e a capacidade de transmissão em um sistema de comunicações ópticas. Para esse controle, os métodos ópticos estão entre os mais utilizados, entre os quais destaca-se o método por difração. Esse processo consiste na identificação dos mínimos ou máximos do padrão de difração quando luz interage transversalmente com a fibra. Neste sentido, parâmetros geométricos tais como a distância entre a fibra e o anteparo de observação (detector), a quantidade de máximos/mínimos de luz e o comprimento de onda da fonte de luz laser, devem ser otimizados afim de aumentar a sensibilidade às mudanças do diâmetro da fibra fabricada. Alguns métodos usuais na etapa do puxamento para a captação e registro do padrão utilizam uma matriz de fotodiodos ou CCD (charge-coupled device). Além disso, o processamento dos dados é realizado através de blocos de circuitos eletrônicos ou então através de um algoritmo para o cálculo da FFT (Fast Fourier Transform), que inserem custos e capacidade de processamento aos métodos. Neste contexto, este trabalho apresenta um estudo para a otimização dos parâmetros geométricos supracitados, utilizando padrões de difração e processamento de imagens. Os padrões de difração foram coletados para o caso de uma fibra estacionária utilizando uma câmera digital e o processamento de imagens foi realizado em MATLAB, de forma a verificar a sensibilidade desse sistema de baixo custo.

O presente trabalho propõe uma estratégia para acessar nós sensores de uma rede de sensores sem fio (RSSF) aglutinados em clusters que se unem em células através de uma topologia híbrida de rádio e/ou fibra. Nesta topologia, a comunicação entre as redes de sensores sem fio e o repetidor será via rádio, enquanto o backhaul de comunicação entre a base e os repetidores será híbrido, podendo utilizar rádio ou fibra. Portanto, a proposta abrange uma topologia flexível, utilizando tanto rádio quanto fibra no backhaul e acesso aos nós sensores via uma rede de sensores sem fio. Para demonstrar a proposta foram feitos testes em uma bancada de emulação de canal utilizando backhaul de fibra entre a base e um elemento repetidor. Estes testes foram realizados na faixa de 915 MHZ, na modulação FSK variando a sua taxa de transmissão, para avaliar a área de cobertura para cada taxa. Como resultados foram obtidas curvas que mostram que para uma RSSI fixa, quanto maior a taxa de transmissão pior será a taxa de erros de bits (BER). E quanto maior o fator de atenuação do ambiente menor será a área de cobertura da rede em todas as taxas testadas. Logo quanto menor a potência recepção, maior a distância entre os nós sensores. Também foram realizados testes em um ambiente real para avaliar os protocolos implementados. Estes testes consistiam no acesso dos nós sensores dos clusters através de múltiplos saltos e medição dos valores de potência de recepção de cada nó sensor e sua taxa de perda de pacotes (PER). Através dos testes realizados foi comprovado o funcionamento da proposta implementada e a topologia flexível proposta.

A fibra óptica apresenta características que favorecem a propagação de sinais eletromagnéticos de um ponto a outro, quando comparada a outros guias de onda. O desempenho máximo da fibra óptica enquanto guia de onda depende da escolha apropriada da topologia de rede, tanto em seu aspecto físico quanto lógico. Na medida em que topologias de rede mais eficientes são apresentadas, abrem-se possibilidades de melhorias para os enlaces já instalados. Após estudo e avaliação técnica criteriosa das características de tráfego da rede, é possível verificar se a topologia física utilizada é a mais indicada e propor alterações que conduzirão à melhoria do desempenho de comunicação. Neste contexto, este trabalho apresenta importantes avanços técnicos para a interconexão dos diversos campi da Universidade Federal do Pampa (UNIPAMPA). Estes avanços podem ser alcançados através da adoção da topologia física mais apropriada a interligar os dez campi da instituição, situados ao longo da fronteira oeste do Rio Grande do Sul, além da reitoria, distribuída em dois endereços na cidade de Bagé. A topologia proposta é do tipo malha e é avaliada em termos orçamento de potência (alcance do sinal), orçamento de tempo (sensibilidade à dispersão) e de custo. Os custos referentes aos componentes da camada física são examinados para três diferentes propostas. A rede proposta ostenta vantagens como uma maior robustez a falhas devido a rompimentos ou ao congestionamento da rede, também permite oferecer uma maior qualidade de serviço em função da redução da latência na rede, ou seja, da redução do tempo necessário à comunicação. Este trabalho poderá ser utilizado para o embasamento técnico, auxiliando em decisões para futuras evoluções na infraestrutura óptica da UNIPAMPA.

Optical communications are becoming even more present in the present world. The constant search for higher bitrates and higher bandwidth is needed since the users’ number is constantly growing. This dissertation approaches the technology for Passive Optical Network NG-PON2. This technology allows the communication in different channels in both downlink and uplink. In my dissertation, it is tested and characterized an optical component that sends and receives data at an extended reach. The data rate used is 10 Gbps in downlink and uplink. So, a prototype of an OLT produced by PICadvanced S.A. was tested in different scenarios. Two OLT are tested in the downlink: a commercial and a non-commercial. Both have an Externally Modulated Laser (EML), allowing a comparison of the performance. Considering the test conditions and the setup don’t change, the differences registered are related to the components used: laser, modulator and SOA. Regarding the upstream, the transmission of information is realized by an ONU, which has a Directly Modulated Laser (DML). Considering that, the test conditions remain the same for both XFP, the differences registered are related to the receiver, which is an APD in both cases. The performance tests realized include the impact of fiber dispersion in downstream for distances up to 40 km and upstream for distances up to 20 km. The fiber dispersion impacts more in transmitters that have a directly modulated laser. The impact of the temperature in both scenarios was analyzed yet considering that the transmitter has a TEC to control the temperature and the receiver does not. Considering an ONU emits data in bursts, the uplink communication was tested with 2 ONU emitting information that an OLT receives and it was possible to conclude that the time slot variance does not impact in the performance. In addition, a simulation tool in VPIPhotonics was developed to allow the optimization of different scenarios tested in the downlink considering the results of the non-commercial OLT.

The need to develop highly sensitive sensors for the detection of bioanalytes is an area that has attracted a great deal of interest in the scientific community. Among these sensors, glucose sensors stand out as the most commercialized on the market. However, there is a diversity of other analytes that can enable physiological monitoring and support clinical decisions or enable early diagnosis of disease. The development of biosensors for detecting cancer biomarkers is one of the fastest growing areas. Regarding breast cancer, conventional diagnostic methods such as mammography currently have high costs and low sensitivity, among other limitations. An alternative are diagnostic methods based on the detection of specific cancer biomarkers that can enable early diagnosis and consequently save millions of patients from premature death. A characteristic of cancer cells is their ability to reprogram their metabolism, which leads to an excessive consumption of glucose. Thus, monitoring the levels of this bioanalyte can help diagnose this disease. This work describes a new optical fiber sensor based on a Fabry-Perot interferometer in which the use of carbon dots (CDs) is investigated and the optical vernier effect (OVE) is exploited as strategies to improve the sensor's performance. The proof of concept of this detection system was carried out using glucose, which proved to be promising for application in the detection of specific cancer biomarkers. By fusing single mode fibers with lateral displacement, a Fabry-Perot cavity was obtained. The sensitivity of the sensor based on this structure was obtained by analyzing its response to different concentrations of glucose, on the presence or absence of CDs. The CDs synthesized in this work were called CAU@CDs, Au@CDs, Pt@CDs and their influence was assessed using two methods: in solution and immobilized on the surface of the optical fiber. In the first method, the sensitivity of the sensor in glucose was 0.183 nm/(mg/mL) and with CAU@CDs and Au@CDs it was 0.175 and 0.204 nm/(mg/mL), respectively. These results indicate a moderate contribution by Au@CDs to greater sensitivity in glucose detection. The results with Pt@CDs were not promising and no detection sensitivity was achieved. In the second method, for the optical fiber sensor functionalized directly with CAU@CDs, it was found that the sensitivity remained in the same order of magnitude but the same was not verified for Au@CDs. Finally, the implementation of the Vernier effect was carried out for the sensor with Au@CDs in solution and led to a magnification of 14.2 in sensitivity and for the sensor with CAU@CDs immobilized on the surface of the optical fiber, a magnification of 15.5 was obtained. The use of the Vernier effect and CDs represent two promising strategies for enhancing biomarker detection.

The developed work was focused on the creation of a data acquisition and processing system capable of extracting information related to an individual's blood pulse wave, using optical systems allied to an electronic support. For that, a fibre optic-based sensor was designed, which uses the variations in the intensity of reflected light, that will be modulated by the movement of the skin as a result of changes in the volume of blood inside the arteries. The signal from the optical sensor is acquired and processed by an electronic system also developed within the scope of this dissertation. It was subsequently developed, a MATLAB® application, which will be responsible for most of the signal processing, including: pulse wave acquisition, extraction and analysis of blood pressure parameters, real time data sampling, serial port or Bluetooth communication and a simple and interactive interface capable of adapting to various types of sensors. In a first phase, a literature review was carried out on various methods of waveform acquisition for obtaining key parameters related to blood pressure using intensity-based sensors. After the literature review, the main system was implemented, which consists of an optical sensor based on optical intensity modulations and a data acquisition, processing, and transmission system. Afterwards, the application is developed where the studied algorithms, the sensor-computer communication via serial port and Bluetooth and the interface for user interaction are implemented. The acquisition system and sensor developed were pre-validated in a hospital environment in comparison with a commercial and commonly used system. The project described throughout the dissertation was carried out in partnership with the company Brightstuff.

The usual exponential approximation for ultraviolet UV absorption in optical fibers could not fit the attenuation coefficient over a broad spectral range. As the UV absorption spectrum is a result of electronic transitions, we propose a Lorentzian function to model this contribution. Experimental results show a good agreement.

We propose a refractive index optical fiber sensor based on the micro cavities generated through the fiber catastrophic fuse effect. This sensor was tested in the measurement of solutions with refractive indices ranging from 1.3320 to 1.4280. The linear dependence of the reflection spectra modulation period as function of the surrounding environment refractive index leads to a resolution of 3 10 4 RIU. The proposed sensor is an innovative solution based on optical fiber damaged by the fuse effect, resulting in a cost effective solution.

In this paper, we report the monitoring of an adobe structure with optical fiber sensors. Static and dynamic measurements were made during a destructive test on a full-scale wall, in which an in-plane cyclic force was imposed, by a hydraulic jack, until the wall collapse. An optical fiber accelerometer and a network of thirteen multiplexed displacement sensors were used to monitor the wall under test. The obtained results demonstrate that the optical fiber sensors had the capacity to monitor this large scale test, showing results similar, with a maximum relative error of 2.08 %, to the results obtained with electronic reference sensors.

The continuous growth of maritime transportation has driven the demand for more sustainable and efficient solutions for supplying energy to ships while docked at port. Conventional shore-to-ship power systems rely on heavy cable connections that are complex to handle, prone towear, and require frequent maintenance. Thiswork presents the development and implementation of a wireless power transfer (WPT) system for shore-to-ship applications, with the goal of increasing safety, flexibility, and reliability in port electrification. The proposed system integrates a power electronic converter composed of a three-level neutral point clamped (3LNPC) rectifier, a three-level inverter connected to the wired interface, and a high-frequency H-bridge inverter associated with the inductive power transfer (IPT) link. The design focuses on scalability, efficiency, and galvanic isolation between the shore grid and the ship, ensuring compliance with maritime safety standards. Communication between the control platform and the power stage is achieved through optical fiber, providing robust, low-latency signal transmission immune to electromagnetic interference. Experimental validation was carried out on a laboratory-scale prototype, demonstrating both the wired connection and wireless power transfer. The results confirm the feasibility of applying IPT technology in maritime environments, paving the way for cleaner, safer, and more convenient shore connection systems.