Publicação
Optical fiber sensors based on a hollow square core fiber
| Resumo: | In the current work, the development of optical fiber sensors based on an antiresonant hollow core fiber was aimed. The sensing structures were developed in a transmission configuration enhancing two antiresonance propagations, along with the multimode interference and Mach-Zehnder interference. With the objective of using these interferometric components as sensing elements, the sensor was employed in both liquid and air media. Initially, a numerical analysis was addressed to both internal and external antiresonances. A simulation on the effective refractive index of the fundamental core mode was also carried out, achieving results that are in good agreement with both numerical and theoretical models. Furthemore, a comparison between the expected and experimental transmission spectra was established observing, in an overall view, similar modulations. In a posterior stage, a characterization of the hollow square core fiber sensor was performed in glucose aqueous solutions. The sensor response was studied to variations in the refractive index, and calibrated to the wavelength range of the optical source utilized. Moreover, the influence of the sensor length was studied, observing the existance of an optimum length where the maximum sensitivity is enhanced. A temperature independent refractive index detection was also established. Still in the framework of this theme, and with the objective of monitoring the evaporation profile of volatile organic compounds, the sensor was embedded in ethanol aqueous solutions. The monitoring of the sensor response towards the solutions was carried out, allowing to successfully attain a real time variation of the ethanol concentration. Finally, the sensor was characterized to different physical parameters in an air environment, where two broadbands were used. In the first band, 1530nm - 1610nm, a characterization to the temperature, curvature, and strain was performed for the Mach-Zehnder interference, external resonance, and multimode interference. In the second broadband, 900nm - 1300nm, the external and internal resonances were characterize to both temperature and curvature. In both cases, the simultaneous measurement of the parameters under study was also proposed. The studied inline sensor revealed to be highly promising in the several experiments that were conducted, where, in many cases, stood out from other sensors that were already reported in the literature. Its reduced dimensions, high robustness, and capability to simultaneously measure different parameters, and making a temperature discrimination, without needing a complex design configuration, makes it extremely viable in the implementation on several applications. |
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| Autores principais: | Pereira, Diana Sofia Antunes |
| Assunto: | Hollow square core fiber Optical fiber sensors Antiresonance Mach-Zehnder interference Multimodal interference |
| Ano: | 2021 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | In the current work, the development of optical fiber sensors based on an antiresonant hollow core fiber was aimed. The sensing structures were developed in a transmission configuration enhancing two antiresonance propagations, along with the multimode interference and Mach-Zehnder interference. With the objective of using these interferometric components as sensing elements, the sensor was employed in both liquid and air media. Initially, a numerical analysis was addressed to both internal and external antiresonances. A simulation on the effective refractive index of the fundamental core mode was also carried out, achieving results that are in good agreement with both numerical and theoretical models. Furthemore, a comparison between the expected and experimental transmission spectra was established observing, in an overall view, similar modulations. In a posterior stage, a characterization of the hollow square core fiber sensor was performed in glucose aqueous solutions. The sensor response was studied to variations in the refractive index, and calibrated to the wavelength range of the optical source utilized. Moreover, the influence of the sensor length was studied, observing the existance of an optimum length where the maximum sensitivity is enhanced. A temperature independent refractive index detection was also established. Still in the framework of this theme, and with the objective of monitoring the evaporation profile of volatile organic compounds, the sensor was embedded in ethanol aqueous solutions. The monitoring of the sensor response towards the solutions was carried out, allowing to successfully attain a real time variation of the ethanol concentration. Finally, the sensor was characterized to different physical parameters in an air environment, where two broadbands were used. In the first band, 1530nm - 1610nm, a characterization to the temperature, curvature, and strain was performed for the Mach-Zehnder interference, external resonance, and multimode interference. In the second broadband, 900nm - 1300nm, the external and internal resonances were characterize to both temperature and curvature. In both cases, the simultaneous measurement of the parameters under study was also proposed. The studied inline sensor revealed to be highly promising in the several experiments that were conducted, where, in many cases, stood out from other sensors that were already reported in the literature. Its reduced dimensions, high robustness, and capability to simultaneously measure different parameters, and making a temperature discrimination, without needing a complex design configuration, makes it extremely viable in the implementation on several applications. |
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