BUSCADOR RECOLECTA

In this work, optical fiber Bragg grating sensors were used to measure water velocity and examine how it was distributed in open channels. Several types of coatings were incorporated into the design of the sensors to examine their effects on the strain that the fibers experienced as a result of the water flow. Due to their low elastic coefficient, which reduced the hysteresis, the results indicated that the aluminum- and acrylate-coated fibers had the best performance. ANSYS-CFX V2020 R2 software was used to model the strain encountered by the fibers under various flow rates to assess the performance of the FBG sensors. The calculations and actual data exhibited good convergence, demonstrating the accuracy of the FBG sensors in determining water velocity. The study illustrated the usability of the proposal in both scenarios by contrasting its application in rivers and channels., This work was supported in part by projects PID2022-137269OB-C21, funded by MCIN/AEI/https://doi.org/10.13039/501100011033 and FEDER 'A way to make Europe', and TED2021-130378B-C22 funded by MCIN/AEI/https://doi.org/10.13039/501100011033 and European Union 'Next generation EU'/PTR

We demonstrate a new optical fiber liquid level sensor based on two sections of capillary optical fibers spliced between single-mode fibers. Last section without coating is in contact with the liquid. A measurement range of 60 mm is obtained when the structure is monitored in reflection by using a FBGs interrogator., This work was supported in part by projects PID2019-107270RB-C02 and PID2022-137269OB-C21 funded by MCIN/AEI/10.13039/501100011033 and FEDER 'A way to make Europe', and TED2021-130378B-C22 funded by MCIN/AEI/10.13039/501100011033 and European Union 'Next generation EU'/PTR.

This paper presents a novel capillary structure for liquid level measurement. The multifiber interferometric structure, which employs two capillary sections, is well-suited to the measurement of liquid levels in both short distances and with high resolution. The measurement range extends up to 60 mm with a resolution of 0.70 mm., This work was supported in part by the MCIN/AEI/10.13039/501100011033 and FEDER "A way to make Europe" under Grant PID2022-137269OB-C21 and in part by the MCIN/AEI/10.13039/501100011033 and European Union "Next generation EU"/PRTR under Grant TED2021-130378B-C22. Open access funding provided by Universidad Pública de Navarra.

In this article, the design and implementation of a bidirectional curvature sensor based on a fiber-optic interferometer are presented. The sensor structure was fabricated by fusing a capillary fiber fragment between single-mode fibers (SMFs), with the addition of a long end capillary to promote a long interferometric section, forming a Fabry-Perot (FP) cavity. Detailed analysis of the curvature data was carried out using machine learning techniques, allowing accurate classification of curvature in both directions of rotation. The experimental results showed excellent agreement (R2: 0.9998) with the predicted values. The sensor exhibits a maximum error of 1.9485°. This approach presents significant potential for applications requiring accurate real-time curvature measurements., This work was supported in part by CIN/AEI/10.13039/501100011033 and FEDER "AWay to Make Europe" under Project PID2022-137269OB and in part by MCIN/AEI/10.13039/501100011033 and European Union "Next Generation EU"/PRTR under Project TED2021-130378B. Open access funding provided by Universidad Publica de Navarra.

We present an interferometric vibration sensor that uses three-core fibers. The transducer is constructed by splicing a segment 20 mm long of a multicore optical fiber (MCF) to a single-mode optical fiber (SMF). The end of the MCF segment is cut off and painted using silver metallic paint. The sensor head is operated in reflection mode. The structure is placed on a polyvinyl chloride (PVC) plate, which is excited with a wide range of frequency signals. The vibrations induce cyclic bending in the MCF segment, resulting in periodic oscillations of the reflected interference spectrum. This device is demonstrated to be suitable to measure vibrations in a frequency range of the order of 300 kHz detecting deformations as small as 0.40μm ., This work was
supported in part by projects PID2019-107270RB-C02 and PID2022-
137269OB-C21, funded by MCIN/AEI/10.13039/501100011033 and
FEDER “A way to make Europe,” and TED2021-130378B-C22 funded
by MCIN/AEI/10.13039/501100011033 and European Union “Next generation EU”/PRTR.

This research explores the impact of cyclic uniaxial transverse deformation on an in-line hollow-core fiber etalon. The structure consists of a 6 mm long section of capillary fiber spliced between two standard single-mode fibers. The optical response of the structure is theoretically analyzed in spectral and transformed domains, evidencing Fabry-Perot and antiresonant interferometric mechanisms. A validation of the theoretical behavior is carried out both through simulation and experimentation. The performance of the structure for uniaxial transverse deformation is subsequently evaluated by tracking the phase of the main component in the transformed domain. The relevance of measuring in the time domain is discussed, demonstrating improved accuracy over wavelength shift and inverse spatial domain methods. Several sensors with different internal diameters underwent cycles of transverse deformation, revealing robust linear trends in every case. On average, the structure demonstrated elastic behavior under deformations up to 42 μm, with a mean sensitivity of 0.174 rad/μm, and mechanical breakage taking place at 58 μm. The results confirmed the suitability of the sensor to withstand uniaxial micro-displacements or pressures, with smaller inner diameter capillary fibers showing the best performance., This work was supported in part by
MCIN/AEI/10.13039/501100011033 and FEDER "A way to make Europe"
under Project PID2019-107270RB-C22 and Project PID2022-137269OB-C21,
in part by MCIN/AEI/10.13039/501100011033 and European Union "Next generation
EU"/PRTR under Project PDC2021-121172-C21 and Project TED2021-
130378B-C22, and in part by the Public University of Navarre under Project
PJUPNA06-2022. Open access funding provided by Public University of
Navarre.

This paper presents a Power-over-Fiber based remote electronic and optical fiber sensors multiplexing scheme. The system architecture consists of a 50-km linear cavity Raman-fiber laser that is used for interrogation of FBG optical fiber sensors. Simultaneously, electronic sensors information is modulated in amplitude while the optical sensors' data are encoded in the spectral information. In order to bias the electronic sensors, the residual power of the Raman pump laser is collected in an energy harvesting unit. This electric power is used for biasing an ATTiny85 control unit and two electro-optical modulators. A proof-of-concept is presented where a couple of optical fiber-Bragg-gratings sensors collect strain information that is self-compensated in temperature according to the digital data achieved from the electronic sensors. A 9.6 kbit/s data rate was achieved using Mach-Zehnder amplitude modulators and a maximum 35 ksample/s was retrieved using a high-speed C-band spectrometer and performing spectral analysis via a software developed in Python. Authors, This work was supported in part by MCIN/AEI/10.13039/501100011033 and FEDER "A way to make Europe", under Project PID2022-137269OB-C21, in part by
MCIN/AEI/10.13039/501100011033 and European Union "Next generation EU"/PRTR under Project TED2021-130378B-C22, and in part by MICINN
under the Beatriz Galindo BEAGAL18/00116 Grant. Open access funding provided by Universidad Publica de Navarra.

Fecha de publicación: 2024-06-21, This study presents a new quasi-distributed vibration sensing approach with a 3-cm spatial resolution, capable of performing multiparameter measurements. In-line interferometers are employed simultaneously as strain point sensors and reflectors for vibration monitoring due to the Doppler effect. The interferometers consist of capillary fiber segments spliced between single-mode fibers, forming a sensing etalon. A study of the characteristics required for the fiber array fabrication is carried out. A 60 cm array comprising 20 sensing sections is used for the proof-of-concept of the technique for strain and vibration sensing. An analysis of the behavior for static strain and vibrations is performed, both individually and simultaneously, using a free-end cantilever experiment., This work was supported in part by MCIN/AEI/10.13039/501100011033 and FEDER "A way to make Europe", under Project PID2022-137269OB-C21, in part by MCIN/AEI/10.13039/501100011033 and European Union "Next generation EU"/PRTR, under Project TED2021-130378B-C22, and in part by the Science and Technology Commission of Shanghai Municipality, China under Grant 23002400300. Open access funding provided by Public University of Navarre.

La tecnología de fibra óptica ha avanzado significativamente en las últimas décadas debido a su rendimiento superior en aplicaciones de comunicación. Basándose en estas innovaciones científicas y tecnológicas, los sensores de fibra óptica (FOS) han surgido como soluciones versátiles a muchas limitaciones de las tecnologías de detección tradicionales. Por ejemplo, los sensores de fibra óptica son químicamente inertes y resistentes a la interferencia electromagnética, lo que los hace ideales para su uso en entornos peligrosos. Además de estos beneficios, los sensores de fibra óptica tienen otras características deseables, como bajo ruido de señal, diseño ligero y compacidad. Estas cualidades únicas han hecho posible su implementación en varias aplicaciones, siendo las que han mostrado mayor éxito, las tecnologías basadas en mecanismos interferométricos, de retrodispersión y de redes de difracción de Bragg (FBGs).
Las estrategias de detección por fibra óptica utilizan diversos mecanismos de transductores y métodos de multiplexación. Sin embargo, se necesitan mejoras, principalmente debido al alto coste de los sensores de fibra en comparación con las tecnologías establecidas. Por lo tanto, las técnicas de multiplexación son esenciales para reducir los costes por sensor. Elegir un enfoque de multiplexación depende del tipo específico de sensor y de los requisitos de la aplicación. Por ejemplo, las redes de difracción de Bragg funcionan bien con la multiplexación por división de longitud de onda, mientras que los sensores interferométricos requieren métodos más complejos.
Aunque el coste es una preocupación principal, el rendimiento y la versatilidad también deben ser considerados para una solución óptima.
El progreso de las Ciudades Inteligentes requiere tecnologías de sensores innovadoras que puedan abordar las complejidades de los sistemas urbanos modernos con precisión, eficiencia y escalabilidad. En este sentido, esta tesis pretende contribuir con nuevas soluciones de sensores de fibra óptica puntuales. Incluye la incorporación de redes de difracción de Bragg y fibras ópticas microestructuradas, desplegando métodos de multiplexación híbridos para redes de sensores escalables, e implementando la tecnología Power over Fiber para facilitar el suministro remoto de energía y la interrogación eficiente de redes de sensores heterogéneas. Estas estructuras pueden adaptarse para aplicaciones tales como la medición de parámetros ambientales y el monitoreo de la calidad del agua y la salud estructural.
El trabajo desarrollado durante esta tesis ha sido realizado en el grupo de investigación de Comunicaciones Ópticas y Aplicaciones Electrónicas de la Universidad Pública de Navarra (UPNA) bajo el Programa de Doctorado en “Tecnologías de la Comunicación, Bioingeniería y Energías Renovables” para el Grado de Doctor en Ingeniería de Telecomunicación. Además, este trabajo se ha desarrollado en parte durante una estancia de investigación en la Universidade de Aveiro (Portugal) bajo la supervisión del Prof. Dr. Carlos Marques., Fiber optic technology has advanced significantly in recent decades due to its superior performance in communication applications. Building on these scientific and technological innovations, fiber optic sensors (FOS) have emerged as versatile solutions to many limitations of traditional sensing technologies. For instance, fiber optic sensors are chemically inert and resistant to electromagnetic interference, making them ideal for use in hazardous environments. In addition to these benefits, fiber optic sensors have other desirable features, including low signal noise, a lightweight design, and compactness. These unique qualities have enabled their deployment in several applications, with technologies based on interferometric mechanisms, backscattering, and Fiber Bragg Gratings (FBGs) showing the most success.
Several fiber optic sensing strategies use various transducer mechanisms and multiplexing methods. However, improvements are needed, primarily due to the high cost of fiber sensors compared to established technologies. Thus, multiplexing techniques are essential for reducing the cost per sensor. Choosing a multiplexing approach depends on the specific sensor type and application requirements. For example, fiber Bragg gratings work well with wavelength division multiplexing, while interferometric sensors require more complex methods. Although cost is a primary concern, performance and versatility must also be considered for an optimal solution.
The progress of Smart Cities requires innovative sensing technologies that can address the complexities of modern urban systems with precision, efficiency, and scalability. In this regard, this thesis aims to contribute to the development of new point optical fiber sensing solutions. It includes the incorporation of fiber Bragg gratings and microstructured optical fibers, deploying hybrid multiplexing methods for scalable sensor networks, and implementing Power over Fiber technology to facilitate remote power provision and efficient interrogation of heterogeneous sensor networks. These structures can be adapted for various applications, including measuring environmental parameters and monitoring water quality and structural integrity.
The work developed during this thesis was conducted in the Optical Communication and Electronic Applications research group at Universidad Pública de Navarra (UPNA) under the Doctorate Program in “Communications Technologies, Bioengineering, and Renewable Energies” for the degree of Doctor of Philosophy (Ph.D.) in Telecommunication Engineering. Additionally, this work was developed in part during a research stay at the Department of Physics and I3N, Universidade de Aveiro, Aveiro, Portugal, under the supervision of Prof. Dr. Carlos Marques., Financial support received: Universidad Pública de Navarra (UPNA) through the pre-doctoral research grants, mobility grants, and complementary grants for doctoral theses; Research project PID2019-107270RB-C02 funded by the Spanish Government Ministerio de Ciencia e Innovación (MCIN)/Agencia Estatal de Investigación (AEI) and FEDER “A way to make Europe”; Research project PDC2021-121172-C01 funded by the Spanish Government MCIN/AEI and the European Union “Next generation EU” / Plan de Recuperación, Transformación y Resilencia (PRTR); Research project TED2021-130378B-C22 funded by the Spanish Government MCIN/AEI and the European Union “Next Generation EU” / PRTR and Research project PID2022-137269OB funded by the Spanish Government CIN/AEI and FEDER “A way to make Europe”., Programa de Doctorado en Tecnologías de las Comunicaciones, Bioingeniería y de las Energías Renovables (RD 99/2011), Bioingeniaritzako eta Komunikazioen eta Energia Berriztagarrien Teknologietako Doktoretza Programa Ofiziala (ED 99/2011)