Diseño, fabricación y caracterización de FBGs e interferómetros en fibra óptica para la monitorización en ambientes adversos

En esta tesis doctoral se presenta el diseño, la implementación y la caracterización de sensores en fibra óptica para la monitorización de diversas magnitudes en ambientes adversos. Se entiende como ambientes adversos aquellas condiciones ambientales externas a los sensores que por su naturaleza dificultan el uso y la fiabilidad a largo plazo de los sistemas de monitorización. Existe una gran variedad de ambientes adversos tales como temperaturas extremas, altas presiones, ambientes químicos o ionizantes, vibraciones o impactos mecánicos, entre otros. Este trabajo de tesis, realizado en el Grupo de Comunicaciones Ópticas y Cuánticas (GCOC) del Instituto de Telecomunicaciones y Aplicaciones Multimedia (ITEAM) de la Universitat Politècnica de València así como el trabajo realizado durante la estancia en la School of Engineering and Applied Science de la Aston University, contempla algunos de estos escenarios, por lo que en el diseño e implementación de los sensores ópticos se han empleado distintas tecnologías ópticas, como las redes de difracción de Bragg (FBGs) o los interferómetros ópticos, con el fin de optimizar las prestaciones de los sensores. En primer lugar, se ha realizado un estudio exhaustivo de las redes de difracción de Bragg regeneradas (RFBGs) para la medida de temperaturas extremas, cercanas a los 1300ºC en algunos casos. Este estudio comprende desde el proceso de fabricación de estos dispositivos fotónicos hasta la caracterización como sensores de temperatura y el estudio de la estabilidad térmica a largo plazo. Se ha realizado también un estudio teórico y experimental sobre la multiplexación de interferómetros modales que, por su sensibilidad y robustez, son muy apropiados para su uso en condiciones ambientales adversas. La técnica de multiplexación desarrollada permite multiplexar los interferómetros modales en distintas configuraciones minimizando la interferencia entre ellos. Por último, se muestra la implementación de un sistema de inscripción de FBGs en fibras ópticas de polímeros y el uso de los dispositivos obtenidos para el diseño, la implementación y la caracterización de sensores ópticos para la medida de curvaturas, grandes deformaciones y deformaciones dinámicas.Barrera Vilar, D. (2013). Diseño, fabricación y caracterización de FBGs e interferómetros en fibra óptica para la monitorización en ambientes adversos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/33399TESISPremios Extraordinarios de tesis doctorale

Tilted fiber Bragg gratings in multicore optical fibers for optical sensing

[EN] We have inscribed a tilted fiber Bragg grating (TFBG) in selected cores of a multicore optical fiber. The presence of the TFBG permits to couple light from the incident guided mode to the cladding modes and to the neighbor cores and this interaction can be used for optical sensing. We have considered to measure different magnitudes: strain, curvature magnitude and direction and external refractive index. The curvature results show a linear dependence of the maximum crosstalk with the curvature magnitude with a sensitivity of 2.5dB/m-1 as the curvature magnitude increases and at the same time a wavelength shift of 70pm/m-1. Changes in the external refractive index gradually vanishes the cladding modes resonances and the crosstalk between the different cores obtaining a reduction of the 90% of the optical spectra integral area for refractive indexes between 1.398 to 1.474.Generalitat Valenciana (APOSTD/2016/015, GVA PROMETEO 2013/012); Ministerio de Economia y Competitividad (MINECO) (TEC2014-60378-C2-1-R).Barrera Vilar, D.; Madrigal-Madrigal, J.; Sales Maicas, S. (2017). Tilted fiber Bragg gratings in multicore optical fibers for optical sensing. Optics Letters. 42(7):1460-1463. doi:10.1364/OL.42.001460S14601463427Flockhart, G. M. H., MacPherson, W. N., Barton, J. S., Jones, J. D. C., Zhang, L., & Bennion, I. (2003). Two-axis bend measurement with Bragg gratings in multicore optical fiber. Optics Letters, 28(6), 387. doi:10.1364/ol.28.000387Fender, A., MacPherson, W. N., Maier, R. R. J., Barton, J. S., George, D. S., Howden, R. I., … Bennion, I. (2008). Two-Axis Temperature-Insensitive Accelerometer Based on Multicore Fiber Bragg Gratings. IEEE Sensors Journal, 8(7), 1292-1298. doi:10.1109/jsen.2008.926878Barrera, D., Gasulla, I., & Sales, S. (2015). Multipoint Two-Dimensional Curvature Optical Fiber Sensor Based on a Nontwisted Homogeneous Four-Core Fiber. Journal of Lightwave Technology, 33(12), 2445-2450. doi:10.1109/jlt.2014.2366556Corres, J. M., Arregui, F. J., & Matías, I. R. (2007). Sensitivity optimization of tapered optical fiber humidity sensors by means of tuning the thickness of nanostructured sensitive coatings. Sensors and Actuators B: Chemical, 122(2), 442-449. doi:10.1016/j.snb.2006.06.008Barrera, D., Villatoro, J., Finazzi, V. P., Cárdenas-Sevilla, G. A., Minkovich, V. P., Sales, S., & Pruneri, V. (2010). Low-Loss Photonic Crystal Fiber Interferometers for Sensor Networks. Journal of Lightwave Technology, 28(24), 3542-3547. doi:10.1109/jlt.2010.2090861Kisała, P., Harasim, D., & Mroczka, J. (2016). Temperature-insensitive simultaneous rotation and displacement (bending) sensor based on tilted fiber Bragg grating. Optics Express, 24(26), 29922. doi:10.1364/oe.24.029922Albert, J., Shao, L.-Y., & Caucheteur, C. (2012). Tilted fiber Bragg grating sensors. Laser & Photonics Reviews, 7(1), 83-108. doi:10.1002/lpor.201100039Chen, C., Caucheteur, C., Mégret, P., & Albert, J. (2007). The sensitivity characteristics of tilted fibre Bragg grating sensors with different cladding thicknesses. Measurement Science and Technology, 18(10), 3117-3122. doi:10.1088/0957-0233/18/10/s11Dong, X., Zhang, H., Liu, B., & Miao, Y. (2010). Tilted fiber Bragg gratings: Principle and sensing applications. Photonic Sensors, 1(1), 6-30. doi:10.1007/s13320-010-0016-xGuo, T., Liu, F., Guan, B.-O., & Albert, J. (2016). [INVITED] Tilted fiber grating mechanical and biochemical sensors. Optics & Laser Technology, 78, 19-33. doi:10.1016/j.optlastec.2015.10.007Cai, Z., Liu, F., Guo, T., Guan, B.-O., Peng, G.-D., & Albert, J. (2015). Evanescently coupled optical fiber refractometer based a tilted fiber Bragg grating and a D-shaped fiber. Optics Express, 23(16), 20971. doi:10.1364/oe.23.020971Gasulla, I., Barrera, D., Hervás, J., & Sales, S. (2017). Spatial Division Multiplexed Microwave Signal processing by selective grating inscription in homogeneous multicore fibers. Scientific Reports, 7(1). doi:10.1038/srep41727Gallagher, M., & Österberg, U. (1993). Time resolved 3.10 eV luminescence in germanium‐doped silica glass. Applied Physics Letters, 63(22), 2987-2989. doi:10.1063/1.110290Komukai, T., & Nakazawa, M. (1996). Fabrication of high-quality long-fiber Bragg grating by monitoring 3.1-eV radiation (400 nm) from GeO defects. IEEE Photonics Technology Letters, 8(11), 1495-1497. doi:10.1109/68.54156

Multipoint two-dimensional curvature optical fiber sensor based on a non-twisted homogeneous four-core fiber

We have implemented a multipoint two-dimensional curvature optical fiber sensor based on a non-twisted homogeneous four-core fiber. A theoretical approach to model the mechanical behavior of these fibers under curvature conditions has been developed. Two shape sensors composed of an array of FBGs inscribed in the four-core fiber have been implemented to corroborate the theoretical analysis with the experimental results. The characterization of the proposed shape sensors showed their ability to measure the curvature radius, the curvature direction and any external applied force relate d to both uniform and non-uniform curvatures with high accuracy.Barrera Vilar, D.; Gasulla Mestre, I.; Sales Maicas, S. (2015). Multipoint two-dimensional curvature optical fiber sensor based on a non-twisted homogeneous four-core fiber. Journal of Lightwave Technology. 33(12):2445-2450. doi:10.1109/JLT.2014.2366556S24452450331

Refractive Index and Temperature Sensing Using Inter-Core Crosstalk in Multicore Fibers

[EN] Multicore optical fibers are of great interest in the optical sensing field. Their core diversity and spatial distribution enable the development of sensing mechanisms that are not possible in single-core fibers. In this paper, we study the use of the inter-core crosstalk phenomena for the implementation of a surrounding refractive index (SRI) sensor. The selective inscription of a tilted fiber Bragg grating (TFBG) intentionally increases the inter-core crosstalk between the inscribed cores and makes it sensitive to the SRI. With this technique we simplify the measurement of the SRI and improve the identification and tracking of the excited cladding modes, as compared with the analysis of the transmission spectrum of a TFBG in single-core fibers. The proposed device is also sensitive to temperature. Temperature is obtained from the crosstalk wavelength shift with a measured sensitivity of 9.75 pm/degrees C. The SRI is obtained from the measurement of the crosstalk optical power. For increasing SRIs the cladding modes gradually fade, reducing the crosstalk optical power. We observed that the higher the tilt, the higher the sensor sensitivity. For a 7 degrees TFBG the SRI sensitivity obtained is -74.2 dB/RIU from 1.31 to 1.39 and -250.8 dB/RIU from 1.39 to 1.44.This work was supported in part by the Spanish Ministry of Economy and Competitiveness under the DIMENSION TEC2017 88029-R Project and in part by the Generalitat Valenciana by PROMETEO 2017/103 research excellency award and IDI/FEDER/2018 GVA Infraestructura. The work of J. Madrigal was supported by Universitat Politecnica de Valencia scholarship PAID-01-18. The work of D. Barrera was supported by Spanish MICINN fellowship IJCI-2017-32476.Madrigal-Madrigal, J.; Barrera Vilar, D.; Sales Maicas, S. (2019). Refractive Index and Temperature Sensing Using Inter-Core Crosstalk in Multicore Fibers. Journal of Lightwave Technology. 37(18):4703-4709. https://doi.org/10.1109/JLT.2019.2917629S47034709371

Long Period Gratings in Multicore Optical Fibers for Directional Curvature Sensor Implementation

[EN] Multicore optical fibers are especially attractive for the fabrication of curvature and shape sensors due to the spatial distribution of the different cores. Fiber Bragg gratings have been used in the past for the implementation of these sensors, however, despite their inherent properties, they have a very limited sensitivity. In this paper, we study the use of long period gratings (LPGs) for the implementation of a directional curvature sensor. We inscribed a set of three different LPGs in a seven core optical fiber using a selective inscription technique. We inscribed a single LPG in the external cores and an array of three LPGs in the central core. We have characterized the proposed sensor for strain, torsion, and curvature magnitude and direction. The proposed sensor shows a linear response for curvature magnitudes from 0 to 1.77 m(-1) with a maximum curvature sensitivity of -4.85 nm/m(-1) and shows a near sinusoidal behavior in all the cores with curvature directions from 0 degrees to 360 degrees. The sensor shows a good insensitivity to strain. The torsion in the multicore optical fibers can be detected and measured using the maximum attenuation of the LPGs in the external cores.This work was supported in part by the Sistema Nacional de Garantia Juvenil under Grant PEJ-2014-A-75865 (Promocion de Empleo Joven e Implantacion de la Garantia Juvenil 2014, MINECO), in part by the Ministry of Economy and Competitiveness under Project TEC2014-60378-C2-1-R, in part by the FINESSE the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Action Grant 722509, and in part by the Generalitat Valenciana under Grant APOSTD/2016/015.Barrera Vilar, D.; Madrigal-Madrigal, J.; Sales Maicas, S. (2018). Long Period Gratings in Multicore Optical Fibers for Directional Curvature Sensor Implementation. Journal of Lightwave Technology. 36(4):1063-1068. https://doi.org/10.1109/JLT.2017.2764951S1063106836

Temperature gradient sensor based on a long-fiber Bragg grating and time-frequency analysis

© [2014 Optical Society of America.]. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.A photonic sensor based on a 10-cm-long fiber Bragg grating (FBG) is presented and experimentally validated that is dedicated to detect the presence and the position of a temperature gradient. The system is based on the measurement of the central frequency distribution of the grating based on time-frequency domain analysis. A short optical pulse, having duration much shorter than the transit time along the grating, is coupled into the FBG, and the back-reflected pulse is scanned by means of an oscilloscope. A spatial resolution of 1 mm, given by half the input pulse duration, is achieved. The proposed sensor is based on a simple configuration and presents a sensing range of 10 cm, which could be further enhanced by fabricating a longer grating. (C) 2014 Optical Society of AmericaThe authors wish to acknowledge the Infraestructura FEDER UPVOV08-3E-008, FEDER UPVOV10-3E-492, the Spanish MCINN through the project TEC2011-29120-C05-05, the Valencian Government through the Ayuda Complementaria ACOMP/2013/146 and the financial support given by the Research Excellency Award Program GVA PROMETEO 2013/012.Ricchiuti, AL.; Barrera Vilar, D.; Nonaka, K.; Sales Maicas, S. (2014). Temperature gradient sensor based on a long-fiber Bragg grating and time-frequency analysis. Optics Letters. 39(19):5729-5731. https://doi.org/10.1364/OL.39.005729S572957313919Culshaw, B. (2004). Optical Fiber Sensor Technologies: Opportunities and—Perhaps—Pitfalls. Journal of Lightwave Technology, 22(1), 39-50. doi:10.1109/jlt.2003.822139Kersey, A. D., Davis, M. A., Patrick, H. J., LeBlanc, M., Koo, K. P., Askins, C. G., … Friebele, E. J. (1997). Fiber grating sensors. Journal of Lightwave Technology, 15(8), 1442-1463. doi:10.1109/50.618377Li, S. Y., Ngo, N. Q., Tjin, S. C., Shum, P., & Zhang, J. (2004). Thermally tunable narrow-bandpass filter based on a linearly chirped fiber Bragg grating. Optics Letters, 29(1), 29. doi:10.1364/ol.29.000029Uno, H., Kojima, A., Shibano, A., & Mikami, O. (1999). Optical wavelength switch using strain-controlled fiber Bragg gratings. Optical Engineering for Sensing and Nanotechnology (ICOSN ’99). doi:10.1117/12.347816Azana, J., & Muriel, M. A. (2001). Temporal self-imaging effects: theory and application for multiplying pulse repetition rates. IEEE Journal of Selected Topics in Quantum Electronics, 7(4), 728-744. doi:10.1109/2944.974245Volanthen, M., Geiger, H., & Dakin, J. P. (1997). Distributed grating sensors using low-coherence reflectometry. Journal of Lightwave Technology, 15(11), 2076-2082. doi:10.1109/50.641525Hotate, K., & Kajiwara, K. (2008). Proposal and experimental verification of Bragg wavelength distribution measurement within a long-length FBG by synthesis of optical coherence function. Optics Express, 16(11), 7881. doi:10.1364/oe.16.007881Sancho, J., Chin, S., Barrera, D., Sales, S., & Thévenaz, L. (2013). Time-frequency analysis of long fiber Bragg gratings with low reflectivity. Optics Express, 21(6), 7171. doi:10.1364/oe.21.007171Ricchiuti, A. L., Barrera, D., Sales, S., Thevenaz, L., & Capmany, J. (2013). Long fiber Bragg grating sensor interrogation using discrete-time microwave photonic filtering techniques. Optics Express, 21(23), 28175. doi:10.1364/oe.21.028175Thévenaz, L., Chin, S., Sancho, J., & Sales, S. (2014). Novel technique for distributed fibre sensing based on faint long gratings (FLOGs). 23rd International Conference on Optical Fibre Sensors. doi:10.1117/12.2059668Barnoski, M. K., Rourke, M. D., Jensen, S. M., & Melville, R. T. (1977). Optical time domain reflectometer. Applied Optics, 16(9), 2375. doi:10.1364/ao.16.00237

Microwave Photonics Filtering Interrogation Technique Under Coherent Regime For Hot Spot Detection on a Weak FBGs Array

[EN] An interrogation technique of cascaded FBG sensors based on a microwave photonics filtering technique under coherent regime is presented. The sensing information of a 5-m fiber coil containing 500 weak FBG with a similar central wavelength is retrieved. The FBGs are 9-mm long and the spatial separation between consecutive FBGs is 1 mm. The principle of operation is based on the calculation of the impulse response by recording the electrical frequency response of the system. Hot spot detection, location, and temperature measurement are demonstrated by experimental measurements with a temperature sensitivity of 0.6 dB/°C in a 10 °C range. Fifteen measurements are recorded in order to average them to reduce noise and smooth the saw tooth appearance typical of coherent measurements. The resolution of the proposed interrogation technique is related to the bandwidth of the electrical measurement. We have obtained a resolution of 20 cm for an electrical bandwidth of 1 GHz. The SNR was larger than 16 dB despite the fact that no amplification was used within the system.This work was supported in part by the Spanish MINECO under Project DIMENSION TEC2017-88029-R, in part by the Generalitat Valenciana (APOSTD/2016/015), in part by the FINESSE funded by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Action under Grant 722509, in part by the Sistema Nacional de Garantia Juvenil under Grant PEJ-2014-A-24709, and in part by the MECD FPU scholarship under Grant FPU13/04675.Hervás-Peralta, J.; Barrera Vilar, D.; Madrigal-Madrigal, J.; Sales Maicas, S. (2018). Microwave Photonics Filtering Interrogation Technique Under Coherent Regime For Hot Spot Detection on a Weak FBGs Array. Journal of Lightwave Technology. 36(4):1039-1045. https://doi.org/10.1109/JLT.2018.2793161S1039104536

Multicore fiber-Bragg-grating-based directional curvature sensor interrogated by a broadband source with a sinusoidal spectrum

[EN] A simple, spectral-drift-insensitive interrogation scheme for a multicore fiber Bragg grating (FBG)-based directional curvature sensor is proposed. The basic principle is to transform the wavelength shift of FBGs into the reflected power variation, which is accomplished by utilizing a broadband source with a sinusoidal spectrum. The closed-form expression of the relationship between the reflected power of the FBG and the corresponding peak wavelength is derived for the first time, to the best of our knowledge; therefore, the peak wavelength of the FBG can be precisely interrogated by using a single photodiode. The experimental results show that, with respect to conventional wavelength measurement by an optical spectrum analyzer, the demodulated wavelength error by our proposed interrogation scheme is within 20 pm. The proposed scheme is further extended to interrogate the direction and curvature using a multicore FBG-based curvature sensor; the interrogated curvature with an error less than 8% is achieved.National Natural Science Foundation of China (NSFC) (61405166); China Scholarship Council (CSC); Generalitat Valenciana (APOSTD/2016/015, GVA PROMETEO 2013/012); Ministerio de Economia y Competitividad (MINECO) (TEC2014-60378-C2-1-R).Zheng, D.; Madrigal-Madrigal, J.; Chen, H.; Barrera Vilar, D.; Sales Maicas, S. (2017). Multicore fiber-Bragg-grating-based directional curvature sensor interrogated by a broadband source with a sinusoidal spectrum. Optics Letters. 42(18):3710-3713. https://doi.org/10.1364/OL.42.003710S37103713421

Microwave Photonic Filtering for Interrogating FBG-Based Multicore Fiber Curvature Sensor

"© 2017 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works."[EN] We propose and experimentally demonstrate an approach to perform high-resolution and temperature-insensitive interrogation of a fiber Bragg grating (FBG)-based multicore fiber (MCF) curvature sensor using a microwave photonics filtering technique. By combining two reflected sample signals from the two FBGs inscribed in MCF and a dispersion device, a two-tap notch microwave photonic filter (MPF) is formed. The notch frequency of MPF is dependent on the time delay difference between the two FBG reflected signals, which is related to wavelength spacing of the two FBGs. Due to the wavelength spacing of the two FBGs is proportional to the curvature, the curvature can be readily interrogated by monitoring the notch frequency of MPF. The proposed interrogation scheme with the sensitivity of 92 MHz/m(-1) is achieved, whilst the sensitivity can be easily adjusted. Moreover, the proposed interrogation scheme is temperature insensitive.This work was supported in part by the National Natural Science Foundation of China under Grant 61405166 and Grant 61775185, in part by the China Scholarship Council, in part by the Generalitat Valenciana under Grant APOSTD/2016/015 and Grant GVA PROMETEO 2013/012, and in part by the Ministerio de Economia y Competitividad under Grant TEC2014-60378-C2-1-R. (Corresponding author: Di Zheng.)Zheng, D.; Madrigal-Madrigal, J.; Barrera Vilar, D.; Sales Maicas, S.; Capmany Francoy, J. (2017). Microwave Photonic Filtering for Interrogating FBG-Based Multicore Fiber Curvature Sensor. IEEE Photonics Technology Letters. 29(20):1707-1710. https://doi.org/10.1109/LPT.2017.2742579S17071710292

Long Weak FBG Sensor Interrogation Using Microwave Photonics Filtering Technique

“© © 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.”A system to interrogate photonic sensors based on long weak fiber Bragg gratings (FBGs) is illustrated and experimentally demonstrated. The FBG sensor is able to detect and measure the precise location of several spot events. The principle of operation is based on a technique used to analyze microwave photonics filters. The long weak FBGs are used as quasi-distributed sensors. Several events can be detected along the FBG device with a spatial accuracy of <1 mm using a modulator and a photodetector with a modest bandwidth of <500 MHz. The simple proposed scheme is intrinsically robust against environmental changes and easy to reconfigure.This work was supported in part by the COST Action under Grant TD1001 through the OFSeSa Project, in part by the Infraestructura through the Federacion Espanola de Enfermedades Raras Project under Grant UPVOV08-3E-008 and Grant UPVOV10-3E-492, in part by the Spanish Ministerio de Ciencia e Innovacion under Project TEC2011-29120-C05-05, in part by the Valencia Government through the Ayuda Complementaria Project under Grant ACOMP/2013/146, in part by the Research Excellency Award Program GVA PROMETEO under Grant 2013/012, and in part by the Swiss Commission for Technology and Innovation under Project 13122.1.Lavinia Ricchiuti, A.; Barrera Vilar, D.; Sales Maicas, S.; Thevenaz, L.; Capmany Francoy, J. (2014). Long Weak FBG Sensor Interrogation Using Microwave Photonics Filtering Technique. IEEE Photonics Technology Letters. 26(20):2039-2042. https://doi.org/10.1109/LPT.2014.2345611S20392042262