Design of optical fiber sensors and interrogation schemes

[ES] Las fibras ópticas son dispositivos muy utilizados en el campo de las telecomunicaciones desde su descubrimiento. En las últimas décadas, las fibras ópticas comenzaron a utilizarse como sensores fotónicos. Los primeros trabajos se centraron en la medición de unas dimensiones físicas en un punto específico. Posteriormente, surgió la posibilidad de medir las propiedades de la fibra óptica en diferentes puntos a lo largo de la fibra. Este tipo de sensores se definen como sensores distribuidos. Los componentes optoelectrónicos fueron desarrollados e investigados para telecomunicaciones. Los avances en las telecomunicaciones hicieron posible el desarrollo de sistemas de interrogación para sensores de fibra óptica, creciendo en paralelo con los avances de las telecomunicaciones. Se desarrollaron sistemas de interrogación de fibra óptica que permiten el uso de una única fibra óptica monomodo estándar como sensor que puede monitorear decenas de miles de puntos de detección al mismo tiempo. Los métodos que extraen la información de detección de la señal reflejada en la fibra óptica son los más empleados debido a la facilidad de acceso al sensor y la flexibilidad de estos sistemas. Los más estudiados son la reflectometría en dominios de tiempo y frecuencia. La reflectometría óptica en el dominio del tiempo (OTDR) fue la primera técnica utilizada para detectar la posición de los fallos en las redes de comunica-ción de fibra óptica. El OTDR sensible a la fase hizo posible detectar la elongación y la temperatura en una posición específica. Paralelamente, los gratings de Bragg (FBG) se convirtieron en los dispositivos más utilizados para implementar sensores en fibra óptica discretos. Se desarrollaron técnicas de multiplexación para realizar la detección en múltiples puntos utilizando FGBs. La reflectometría realizada interrogando arrays de FBG débiles demuestra que mejora el rendimiento del sistema en comparación al uso de una fibra monomodo. Los sistemas de interrogatorio actuales tienen algunos inconvenientes. Algunos de ellos son velocidad de interrogatorio limitada, grandes dimensiones y alto costo. En esta tesis doctoral se desarrollaron nuevos sistemas de interrogación y sensores de fibra óptica para superar algunos de estos inconvenientes. Los sensores de fibra óptica de plástico demuestran ser una plataforma innovadora para desarrollar nuevos sensores y sistemas de interrogación de bajo costo y fáciles de implementar para fibras de plástico comerciales. Se investigó la reflectometría en el dominio del tiempo y las técnicas fotónicas de microondas para la interrogación de una matriz de rejillas débiles que permitieron simplificar el sistema de interrogación para la detección de temperatura y vibración.[CA] Les fibres òptiques són dispositius molt utilitzats en el camp de les telecomunica-cions des del seu descobriment. En les últimes dècades, les fibres òptiques van començar a utilitzar-se com a sensors fotònics. Els primers treballs es van centrar en el mesurament d'unes dimensions físiques en un punt específic. Posteriorment, va sorgir la possibilitat de mesurar les propietats de la fibra òptica en diferents punts al llarg de la fibra. Aquest tipus de sensors es defineixen com a sensors distribüits. Els components optoelectrònics van ser desenvolupats i investigats per a telecomunicacions. Els avanços en les telecomunicacions van fer possi-ble el desenvolupament de sistemes d'interrogació per a sensors de fibra òptica, creixent en paral·lel amb els avanços de les telecomunicacions. Es van desenvolupar sistemes d'interrogació de fibra òptica que permeten l'ús d'una única fibra òptica monomodo estàndard com a sensor que pot monitorar desenes de milers de punts de detecció al mateix temps. Els mètodes que extreuen la informació de detecció del senyal reflectit en la fibra òptica són els més utilitzats a causa de la facilitat d'accés al sensor i la flexibilitat d'aquests sistemes. Els més estudiats són la reflectometría en dominis de temps i freqüència. La reflectometría òptica en el domini del temps (OTDR) va ser la primera tècnica utilitzada per a detectar la posició de les fallades en les xarxes de comunicació de fibra òptica. El OTDR sensible a la fase va fer possible detectar l'elongació i la temperatura en una posició específica. Paral·lelament, els gratings de Bragg (FBG) es van convertir en els dispositius més utilitzats per a implementar sensors en fibra òptica discrets. Es van desenvolupar tècniques de multiplexació per a realitzar la detecció en múltiples punts utilitzant FGBs. La reflectometría realitzada interrogant arrays de FBG febles demostra que millora el rendiment del sistema en comparació a l'ús d'una fibra monomodo. Els sistemes d'interrogatori actuals tenen alguns inconvenients. Alguns d'ells són velocitat d'interrogatori limitada, voluminositat i alt cost. En aquesta tesi doctoral es van desenvolupar nous sistemes d'interrogació i sensors de fibra òptica per a superar alguns d'aquests inconvenients. Els sensors de fibra òptica de plàstic demostren ser una plataforma innovadora per a desenvolupar nous sensors i siste-mes d'interrogació de baix cost i fàcils d'implementar per a fibres de plàstic comercials. Es va investigar la reflectometría en el domini del temps i les tècniques fotòniques de microones per a la interrogació d'una matriu de reixetes febles que van permetre simplificar el sistema d'interrogació per a la detecció de temperatura i vibració.[EN] Optical fibers are devices largely used in telecommunication field since their discovery. In the last decades, optical fibers started to be used as photonic sensors. The first works were focused on the measurement of physical dimensions to a specific point. Afterward, emerged the possibility to measure the optical fiber properties at different locations along the fiber. These kinds of sensors are defined as distributed sensors. The optoelectronic components were developed and investigated for telecommunications. The progress in telecommunication made possible the development of optical fiber sensors interrogation systems, growing in parallel with the advances of telecommunications. Optical fiber interrogation systems were developed to use a single standard monomode optical fiber as a sensor that can monitor tens of thousands of sensing points at the same time. The methods that extract the sensing information from the backscattered signal in the optical fiber are widely employed because of the easiness of access to the sensor element and the flexibility of these systems. The most studied are the reflectometry in time and frequency domains. The optical time domain reflectometry (OTDR) was the first technique used to detect the position of the failures in the optical fiber communication networks. Using phase sensitive OTDR it is possible to sense strain and temperature at a specific position. In parallel, fiber Bragg gratings (FBGs) became the most widely used devices to implement discrete optical fiber sensors. Multiplexing techniques were developed to perform multi points sensing using these gratings. The reflectometry performed interrogating weak FBGs arrays demonstrate to improve the performance of the system employing a single mode fiber. The interrogation systems nowadays have some drawbacks. Some of them are limited speed of interrogation, bulkiness, and high cost. New interrogation systems and optical fiber sensors were developed in this doctoral thesis to overcome some of these drawbacks. Plastic optical fiber sensors demonstrate to be an innovative platform to develop both new sensors and low cost, easy to implement interrogation systems for commercial plastic fibers. Reflectometry in time domain and microwave photonic techniques were investigated for the interrogation of weak gratings array allowed to simplify the interrogation system for the sensing of temperature and vibration.I would like to greatly thank the European Union’s Horizon 2020 Research and Innovation Program that funded the research described in this thesis under the Marie Sklodowska-Curie Action Grant Agreement 722509.Sartiano, D. (2021). Design of optical fiber sensors and interrogation schemes [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/161357TESI

Monitoring temperature and vibration in a long weak grating array with short-pulse generation using a compact gain-switching laser diode module

© 2019 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.[EN] Quasi-distributed temperature sensing and single point vibration sensing were performed. Ultrashort pulses generated by a gain-switching laser were used to interrogate a fiber Bragg gratings (FBG) array sensor. Temperature changes were measured down to 1 degrees C with sub-centimeter spatial resolution. The advantages of our fast interrogation setup were exploited, as the higher frequency limit of a dynamic measure that can be sensed is limited by the time needed to generate the optical pulse and to acquire the data from the sensor. The experimental approach described in this paper can sense mechanical vibrations up to a frequency of 245 kHz and a strain resolution as low as 1.2 mu epsilon.H2020 Marie Sklodowska-Curie Actions (MSCA-ITN-ETN-722509); Ministerio de Economia y Competitividad (DIMENSION TEC2017 88029-R); Generalitat Valenciana (PROMETEO 2017/103).Sartiano, D.; Sales Maicas, S. (2019). Monitoring temperature and vibration in a long weak grating array with short-pulse generation using a compact gain-switching laser diode module. Optics Express. 27(26):38661-38669. https://doi.org/10.1364/OE.379106S38661386692726Tosi, D. (2017). Review and Analysis of Peak Tracking Techniques for Fiber Bragg Grating Sensors. Sensors, 17(10), 2368. doi:10.3390/s17102368Mihailov, S. J. (2012). Fiber Bragg Grating Sensors for Harsh Environments. Sensors, 12(2), 1898-1918. doi:10.3390/s120201898Chan, P. K. C., Jin, W., Gong, J. M., & Demokan, N. S. (1999). Multiplexing of fiber Bragg grating sensors using a FMCW technique. IEEE Photonics Technology Letters, 11(11), 1470-1472. doi:10.1109/68.803082Pastor-Graells, J., Martins, H. F., Garcia-Ruiz, A., Martin-Lopez, S., & Gonzalez-Herraez, M. (2016). Single-shot distributed temperature and strain tracking using direct detection phase-sensitive OTDR with chirped pulses. Optics Express, 24(12), 13121. doi:10.1364/oe.24.013121Martins, H. F., Martin-Lopez, S., Corredera, P., Filograno, M. L., Frazao, O., & Gonzalez-Herraez, M. (2013). Coherent Noise Reduction in High Visibility Phase-Sensitive Optical Time Domain Reflectometer for Distributed Sensing of Ultrasonic Waves. Journal of Lightwave Technology, 31(23), 3631-3637. doi:10.1109/jlt.2013.2286223Ou, Y., Zhou, C., Qian, L., Fan, D., Cheng, C., & Guo, H. (2015). Large-capacity multiplexing of near-identical weak fiber Bragg gratings using frequency-shifted interferometry. Optics Express, 23(24), 31484. doi:10.1364/oe.23.031484Hervas, J., Barrera, D., Madrigal, J., & Sales, 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. doi:10.1109/jlt.2018.2793161Ricchiuti, A. L., Hervás, J., & Sales, S. (2016). [INVITED] Cascade FBGs distributed sensors interrogation using microwave photonics filtering techniques. Optics & Laser Technology, 77, 144-150. doi:10.1016/j.optlastec.2015.09.003Nonaka, K., Mizuno, H., Song, H., Kitaoka, N., & Otani, A. (2008). Low-Time-Jitter Short-Pulse Generator Using Compact Gain-Switching Laser Diode Module With Optical Feedback Fiber Line. Japanese Journal of Applied Physics, 47(8), 6754-6756. doi:10.1143/jjap.47.6754Cusano, A., Cutolo, A., Nasser, J., Giordano, M., & Calabrò, A. (2004). Dynamic strain measurements by fibre Bragg grating sensor. Sensors and Actuators A: Physical, 110(1-3), 276-281. doi:10.1016/j.sna.2003.10.031Takahashi, N., Yoshimura, K., & Takahashi, S. (2001). Fiber Bragg Grating Vibration Sensor Using Incoherent Light. Japanese Journal of Applied Physics, 40(Part 1, No. 5B), 3632-3636. doi:10.1143/jjap.40.3632Tsuda, H. (2010). Fiber Bragg grating vibration-sensing system, insensitive to Bragg wavelength and employing fiber ring laser. Optics Letters, 35(14), 2349. doi:10.1364/ol.35.002349Lau, K. Y. (1988). Gain switching of semiconductor injection lasers. Applied Physics Letters, 52(4), 257-259. doi:10.1063/1.9948

Disegno e implementazione di un framework per la misura qualitativa dei servizi di rete.

Data la molteplicità e l'eterogeneità dei servizi di rete si ha la necessità di nuovi strumenti di monitoraggio. Quelli attualmente disponibili, offrono risultati orientati alle metriche di rete, i quali sono difficilmente interpretabili da parte degli utenti, che invece ragionano in termini di servizi. Questo lavoro di tesi propone dunque una metodologia per l'analisi di alcuni di essi basati su HTTP, per i quali sono state de finite alcune metriche applicative interpretabili dagli utenti. In particolare viene proposta una metodologia per: - Classifi care il traffico HTTP in base ai servizi di rete utilizzati (ad esempio posta elettronica, streaming video, aggiornamento di software). - Correlazione e aggregazione delle singole richieste, per ricavare l'albero di navigazione, da cui poter determinare le attività svolte dell'utente. - Analizzare la qualità dell'esperienza utente relativa al servizio web e a quello di streaming offerto da YouTube. Al fi ne di validare questo lavoro e stato sviluppato un framework, su cui si basano alcune applicazioni per l'analisi del traffico di rete. La sperimentazione, effettuata analizzando pacchetti catturati da un ISP regionale, ha confermato la possibilità di ottenere informazioni ad alto livello, sia sulle attività svolte dagli utenti, che sulla qualità percepita dei servizi di rete studiati. I risultati ottenuti rendono attuabile l'estensione del framework per lo studio di altri servizi Internet, come ad esempio la posta elettronica, messaggistica istantanea o multiplayer, in cui vi è la necessità di analizzare l'esperienza utente relativa

Using Embeddings for Both Entity Recognition and Linking in Tweets

L’articolo descrive la nostra partecipazione al task di Named Entity rEcognition and Linking in Italian Tweets (NEEL-IT) a Evalita 2016. Il nostro approccio si basa sull’utilizzo di un Named Entity tagger che sfrutta embeddings sia character-level che word-level. I primi consentono di apprendere le idiosincrasie della scrittura nei tweet. L’uso di un tagger completo consente di riconoscere uno spettro più ampio di entità rispetto a quelle conosciute per la loro presenza in Knowledge Base o gazetteer. Le prove sottomesse hanno ottenuto il primo, secondo e quarto dei punteggi ufficiali.The paper describes our sub-missions to the task on Named Entity rEcognition and Linking in Italian Tweets (NEEL-IT) at Evalita 2016. Our approach relies on a technique of Named Entity tagging that exploits both charac-ter-level and word-level embeddings. Character-based embeddings allow learn-ing the idiosyncrasies of the language used in tweets. Using a full-blown Named Entity tagger allows recognizing a wider range of entities than those well known by their presence in a Knowledge Base or gazetteer. Our submissions achieved first, second and fourth top offi-cial scores

Low Cost Plastic Optical Fiber Pressure Sensor Embedded in Mattress for Vital Signal Monitoring

[EN] The aim of this paper is to report the design of a low-cost plastic optical fiber (POF) pressure sensor, embedded in a mattress. We report the design of a multipoint sensor, a cheap alternative to the most common fiber sensors. The sensor is implemented using Arduino board, standard LEDs for optical communication in POF (¿ = 645 nm) and a silicon light sensor. The Super ESKA® plastic fibers were used to implement the fiber intensity sensor, arranged in a 4 × 4 matrix. During the breathing cycles, the force transmitted from the lungs to the thorax is in the order of tens of Newtons, and the respiration rate is of one breath every 2¿5 s (0.2¿0.5 Hz). The sensor has a resolution of force applied on a single point of 2.2¿4.5%/N on the normalized voltage output, and a bandwidth of 10 Hz, it is then suitable to monitor the respiration movements. Another issue to be addressed is the presence of hysteresis over load cycles. The sensor was loaded cyclically to estimate the drift of the system, and the hysteresis was found to be negligible.This research was supported by FINESSE project, funded by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Action grant agreement No. 722509 and PROMETEO 2017/103 Tecnologias y Aplicaciones Futura de la Fotonica de Microondas.Sartiano, D.; Sales Maicas, S. (2017). Low Cost Plastic Optical Fiber Pressure Sensor Embedded in Mattress for Vital Signal Monitoring. Sensors. 17 (12)(2900):1-11. https://doi.org/10.3390/s17122900S11117 (12)290

Sub-cm Temperature Monitoring of 500 Weak Gratings Array Through Chirped Ultra-Short Light Pulses

© 2019 Optical Society of America]. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved.[EN] We developed a temperature quasi-distributed sensing system interrogating a 500 weak fiber Bragg gratings (FBGs) array of 5 meters. It was possible to sense temperature changes down to 1°C with sub-centimeter spatial resolution.This research was supported by FINESSE project, funded by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska -Curie Action grant agreement n° 722509. It was also supported by the Ministry of Economy and Competitiveness project DIMENSION TEC2017 and by the Generalitat Valenciana project PROMETEO 2017/017.Sartiano, D.; Madrigal-Madrigal, J.; Sales Maicas, S. (2019). Sub-cm Temperature Monitoring of 500 Weak Gratings Array Through Chirped Ultra-Short Light Pulses. OSA. 1-2. http://hdl.handle.net/10251/180694S1

Bend-Direction and Rotation Plastic Optical Fiber Sensor

[EN] A plastic filament of poly (methyl methacrylate) (PMMA) was fabricated by extrusion. The mode confinement was simulated using numerical software. The idea is to study how the light intensity changes inside the plastic optical fiber (POF) when a bending in multiple directions is applied. The results obtained from the simulation were compared to the experimental observations. The non-circular shape of the POF allows sensing a rotation applied as well. The angle of rotation was obtained processing two images of the end facet of the fiber (one with the fiber in a reference position and one with the rotated fiber), using an intensity-based automatic image registration. The accuracy in the rotation calculation was of 0.01 degrees.FINESSE project, funded by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Action grant agreement no 722509. Ministry of Economy and Competitiveness project DIMENSION TEC2017 and by the Generalitat Valenciana project PROMETEO 2017/017.Sartiano, D.; Geernaert, T.; Torres Roca, E.; Sales Maicas, S. (2020). Bend-Direction and Rotation Plastic Optical Fiber Sensor. Sensors. 20(18):1-9. https://doi.org/10.3390/s20185405S19201

High-voltage Sensor Based on Fiber Bragg Grating in Fibers with Electrodes

[EN] This work describes the use of FBGs inscribed in optical fiber with electrodes for voltage sensing. The results show a quadratic voltage dependence. The device can be explored for a multipoint, single-ended voltage sensing device.The authors acknowledge financial support from the FINESSE project. FINESSE is funded by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska - Curie grant agreement n° 722509. Partial funding from K. A. Wallenberg Foundation and the Swedish Science Council is gratefully acknowledged. We also thank Kenny Hey Tow (RISE, Sweden) for useful discussions.Pereira, JMB.; Sartiano, D.; Hervás, J.; Barrera, D.; Madrigal-Madrigal, J.; Sales Maicas, S.; Laurell, F.... (2020). High-voltage Sensor Based on Fiber Bragg Grating in Fibers with Electrodes. IEEE. 1-2. http://hdl.handle.net/10251/177479S1

Hypochromicity in red blood cells: an experimental and theoretical investigation

Multiwavelength UV-visible transmission spectrophotometry is a useful tool for the examination of micron-size particle suspensions in the context of particle size and chemical composition. This paper reports the reliability of this method to characterize the spectra of purified red blood cells both in their physiological state and with modified hemoglobin content. Previous studies have suggested the contribution of hypochromism on the particle spectra caused by the close electronic interaction of the encapsulated chromophores. Our research shows, however, that this perceived hypochromism can be accounted for by considering two important issues: the acceptance angle of the instrument and the combined scattering and absorption effect of light on the particles. In order to establish these ideas, spectral analysis was performed on purified and modified red cells where the latter was accomplished with a modified hypotonic shock protocol that altered the hemoglobin concentration within the cells. Moreover, the Mie theory was used to successfully simulate the spectral features and trends of the red cells. With this combination of experimental and theoretical exploration, definition of hypochromism has been extended to two subcategories

Rapid Selection and Proliferation of CD133(+) Cells from Cancer Cell Lines: Chemotherapeutic Implications

Cancer stem cells (CSCs) are considered a subset of the bulk tumor responsible for initiating and maintaining the disease. Several surface cellular markers have been recently used to identify CSCs. Among those is CD133, which is expressed by hematopoietic progenitor cells as well as embryonic stem cells and various cancers. We have recently isolated and cultured CD133 positive [CD133(+)] cells from various cancer cell lines using a NASA developed Hydrodynamic Focusing Bioreactor (HFB) (Celdyne, Houston, TX). For comparison, another bioreactor, the rotary cell culture system (RCCS) manufactured by Synthecon (Houston, TX) was used. Both the HFB and the RCCS bioreactors simulate aspects of hypogravity. In our study, the HFB increased CD133(+) cell growth from various cell lines compared to the RCCS vessel and to normal gravity control. We observed a (+)15-fold proliferation of the CD133(+) cellular fraction with cancer cells that were cultured for 7-days at optimized conditions. The RCCS vessel instead yielded a (−)4.8-fold decrease in the CD133(+)cellular fraction respect to the HFB after 7-days of culture. Interestingly, we also found that the hypogravity environment of the HFB greatly sensitized the CD133(+) cancer cells, which are normally resistant to chemo treatment, to become susceptible to various chemotherapeutic agents, paving the way to less toxic and more effective chemotherapeutic treatment in patients. To be able to test the efficacy of cytotoxic agents in vitro prior to their use in clinical setting on cancer cells as well as on cancer stem cells may pave the way to more effective chemotherapeutic strategies in patients. This could be an important advancement in the therapeutic options of oncologic patients, allowing for more targeted and personalized chemotherapy regimens as well as for higher response rates