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A numerical approach into new designs for SPR sensors in D-type optical fibers

Publication . Santos, Diego Filipe De Nóbrega Dos; Baptista, José Manuel Rocha Teixeira; Guerreiro, Ariel Ricardo Negrão Silva

This thesis investigates how to improve the performance of current designs of optical fiber sensors based on Surface Plasmon Resonance, and how to use a better understanding of the physical and sensing principles behind them to propose new sensing concepts and ideas. We adopt a methodology based on numerical simulations because they provide a better insight onto the operation of these sensors and because they allow an easy and quick way of testing new designs and concepts without the need to fabricate the sensors. We also show that these simulations have a good agreement with experimental results. We adopt a systematic approach to investigate the various parameters that influence the sensor performance, and present different sensors designs, where we study the localization, optical properties, shape and size of the metal components, combined with different type of fibers, resulting in the coupling between the plasmon and optical modes. Furthermore, we verify that choosing the optical modes used in sensing in multimode fibers can also have advantages. We investigate the use of modern artificial materials, such as metamaterials, as well as the inclusion of multiple wires in the fiber to enhance the performance of the SPR sensor. At a more fundamental level, we show that the control of the coupling between multiple plasmon modes in metal components and the optical modes in the fiber constitutes a new way to improve the performance of the sensor and can be inclusively used to develop a new type of SPR sensors capable of measuring simultaneously two variables, such as the external refractive index and temperature

2017-07-21Doctoral thesis

Open access