Open Access
Ultra-long (290 km) remote interrogation sensor network based on a random distributed feedback fiber laser
(Optical Society of America, 2018) Miguel Soto, Verónica de; Leandro González, Daniel; López-Amo Sáinz, Manuel; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this work, an interferometric sensor has been interrogated 290 km away from the monitoring station, reaching the longest distance in fiber optic sensing up to date. This has been attained by employing a double-pumped random distributed feedback fiber laser as the light source for a fiber optic low-coherence interferometry scheme. Additionally, the capability of the system to achieve coherence multiplexing for ultra-long range measurements (up to 270 km) has been proved, without presenting crosstalk between the sensors. The use of coherence multiplexing together with a random distributed feedback fiber laser addresses two of the main limitations of long-range sensing setups: their limited multiplexing capability and the need to reach the maximum monitoring distance.
Open Access
L-band multiwavelength single-longitudinal mode fiber laser for sensing applications
(IEEE / OSA, 2012) Pérez Herrera, Rosa Ana; Ullán Nieto, Ángel; Leandro González, Daniel; Fernández Vallejo, Montserrat; Quintela, M. A.; Loayssa Lara, Alayn; López Higuera, José Miguel; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, a novel single-longitudinal-mode (SLM) four-wavelength laser configuration for sensing applications in the L-band is proposed and experimentally demonstrated. The sensor system presented here is based on ring resonators, and employs fiber Bragg gratings to select the operation wavelengths. The stable SLM operation is guaranteed when all the lasing channels present similar output powers. It is also experimentally demonstrated that when a SLMbehavior is achieved, lower output power fluctuations are obtained. Characterization of the lasing structure for temperature sensing is also shown.
Open Access
New multiplexing structures for fiber optic sensors
(2016) Leandro González, Daniel; López-Amo Sáinz, Manuel; Díaz Lucas, Silvia; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
El campo de la fibra óptica ha sufrido una rápida evolución durante las últimas décadas debido a sus buenas prestaciones en aplicaciones de telecomunicaciones. Aprovechando este avance científico y técnico en componentes fotónicos, los sensores de fibra óptica han emergido como una solución flexible para solventar algunas de las principales limitaciones sufridas por los sensores convencionales. Por ejemplo, la fibra óptica es químicamente inerte y electromagnéticamente pasiva. Por lo tanto, puede trabajar en entornos explosivos como depósitos de combustible, o con campos eléctricos intensos. Otra cualidad importante de los sensores de fibra óptica es que son compactos, pequeños, ligeros e inducen un bajo ruido de intensidad. Estas propiedades se han aprovechado en diferentes aplicaciones, siendo particularmente exitosos los giróscopos de fibra óptica y las soluciones basadas en redes de difracción de Bragg. Se han presentado hasta la fecha numerosos planteamientos para interrogar sensores de fibra óptica, utilizando diferentes mecanismos de transducción, técnicas de multiplexación o interrogación, etc. Sin embargo, todavía quedan algunos aspectos que mejorar. Posiblemente, el mayor inconveniente de los sensores de fibra, comparados con otras tecnologías asentadas, sea su coste relativamente alto. Teniendo esto en cuenta, las técnicas de multiplexación de sensores son especialmente importantes debido a que supone la reducción del coste por cada sensor. Se pueden utilizar diferentes técnicas de multiplexación dependiendo del tipo de sensor y de los requisitos de la aplicación. Por ejemplo, las redes de difracción de Bragg son especialmente adecuadas para utilizarse en multiplexación por longitud de onda, mientras que los sensores interferométricos normalmente requieren soluciones más complejas. Además de reducir el coste, hay otros factores de los sensores de fibra óptica que pueden mejorarse, como la relación señal-ruido, la resolución, la estabilidad y la interrogación remota a largas distancias entre otros. En este contexto, esta tesis pretende contribuir al desarrollo de nuevas redes de sensores, haciendo especial hincapié en nuevas técnicas y topologías de multiplexación. De esta manera, se han multiplexado sensores interferométricos y redes de difracción Bragg siguiendo nuevos esquemas. Estas redes incluyen diferentes planteamientos, que pueden dividirse en dos grandes grupos: redes pasivas con multiplexación de sensores interferométricos y redes activas basadas en láseres de fibra. Además de las técnicas de multiplexación, también se han explorado otras alternativas, como la operación mono-frecuencia, la interrogación remota a largas distancias o la realización de medidas de alta resolución. Asimismo, se han analizado las capacidades de los láseres de fibra con reflectores distribuidos random para interrogación de sensores.
Open Access
High sensitivity fiber-optic liquid level sensor using biconical tapered fibers
(Optical Society of America, 2018) Júdez Colorado, Aitor; Leandro González, Daniel; Pérez Herrera, Rosa Ana; Galarza Galarza, Marko; López-Amo Sáinz, Manuel; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
A liquid level sensor is presented using a biconical tapered standard single-mode fiber, being its main characteristic an outstanding sensitivity for a low cost transducer. Temperature compensation is enabled with the same interrogation equipment.
Open Access
High resolution polarization-independent highbirefringence fiber loop mirror sensor
(Optical Society of America, 2015) Leandro González, Daniel; Bravo Acha, Mikel; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, two all polarization-maintaining (PM) highbirefringence (Hi-Bi) fiber loop mirrors (FLM) which are immune to external polarization perturbations are validated both theoretically and experimentally. Simplified and stable versions of classical FLMs were attained using a PM-coupler and by fusing the different Hi-Bi fiber sections with an adequate rotation angle between them. Since the polarization states are fixed along the whole fiber loop, no polarization controllers are needed. This simplifies the operation and increases the stability of the systems, which were also validated as ultra-high resolution sensors, experimentally obtaining a resolution of 6.2·10−4 °C without averaging.
Open Access
Interferometric vs wavelength selective optical fiber sensors for cryogenic temperature measurements
(SPIE, 2017) Miguel Soto, Verónica de; Leandro González, Daniel; López Aldaba, Aitor; Beato López, Juan Jesús; Pérez de Landazábal Berganzo, José Ignacio; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; López-Amo Sáinz, Manuel; Ingeniaritza Elektrikoa eta Elektronikoa; Fisika; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería Eléctrica y Electrónica; Física
In this work, a preliminary study of the behavior of two different interferometric fiber optic sensors and two different wavelength selective fiber optic sensors is performed. A photonic cristal fiber Fabry-Pérot interferometer, a Sagnac interferometer, a commercial fiber Bragg grating (FBG) and a π-phase shifted fiber Bragg grating interrogated in a random distributed feedback fiber laser are analyzed. A comparison of their sensitivities and resolutions is carried out to analyze their performance as sensors for cryogenic temperatures, taking into account their advantages and drawbacks.
Open Access
High-resolution transversal load sensor using a random distributed feedback fiber laser
(SPIE, 2016) Miguel Soto, Verónica de; Leandro González, Daniel; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, a new application of random distributed feedback lasers to fiber optic sensing has been presented. The particular properties of these lasers, such as the lack of longitudinal modes and high stability, have been exploited to monitor transversal load using a phase-shifted fiber Bragg grating (PS-FBG), obtaining a resolution of 1g and a sensitivity of 3.95GHz/Kg. Due to the PS-FBG birefringence and the load-interrelated transmission lines generated by the PS-FBG along the orthogonal polarization directions, the beating of the two emission lines generated in the laser can be monitored in the electrical domain. As a result, transversal load applied on the sensor can be measured.
Open Access
Optical fiber sensors for asphalt structures monitoring
(Optica Publishing Group, 2016) Bravo Acha, Mikel; Rota Rodrigo, Sergio; Leandro González, Daniel; Loayssa Lara, Alayn; Urricelqui Polvorinos, Javier; Bravo Acha, A.; Bravo Navas, M.; Mitxelena, J. R.; Martínez Mazo, J. J.; López-Amo Sáinz, Manuel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A novel optical fiber installation method was explored for asphalt monitoring. Glassfiber polymer encapsulated SMF was installed in the intermediate and surface layers in order to study the strain sensitivity with a distributed strain interrogator.
Open Access
Narrow-linewidth multi-wavelength random distributed feedback laser
(IEEE / OSA, 2015) Leandro González, Daniel; Rota Rodrigo, Sergio; Ardanaz, Diego; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, narrow-band emission lines are generated by means of two random distributed feedback fiber laser schemes. Spectral line-widths as narrow as 3.2 pm have been measured, which significantly improves previous reported results. The laser is analyzed with the aim of obtaining a spectral line-width as narrow as possible. Additionally a variation of this setup for multi-wavelength operation is also validated. Both schemes present a simple topology that use a combination of phase-shifted fiber Bragg gratings and regular fiber Bragg gratings as filtering elements.
Open Access
Real-time FFT analysis for interferometric sensors multiplexing
(IEEE / OSA, 2015) Leandro González, Daniel; Bravo Acha, Mikel; Ortigosa Cayetano, Amaia; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, a theoretical and experimental study of two interferometric sensor multiplexing schemes has been carried out by means of the fast Fourier transform (FFT) analysis. This work addresses one of the main drawbacks of photonic crystal fiber (PCF) sensors, that is, its multiplexing capability. Using a commercial optical interrogator combined with a simple FFT measurement technique, the simultaneous real-time monitoring of several PCF sensors is achieved. A theoretical analysis has been performed where simulations matched with the experimental results. For the experimental verification, highly birefringent (HiBi) fiber sections that operated as sensing elements were multiplexed and tested in two configurations. Due to the FFT analysis, both multiplexing schemes can be properly interrogated by monitoring the FFT phase change at the characteristic spatial-frequency of each sensor. For this purpose a commercial interrogator and a custom Matlab program were used for computing the FFT and for monitoring the FFT phase change in real-time (1 Hz).