Self-referenced temperature sensor based on a polymer optical fiber macro-bend

This proceeding at : 23 rd International Conference en Optical Fiber Sensors (OFS23). Took place in 2014, June, 02-06, in Santander (Spain).The design and development of a plastic optical fiber (POF) macrobend temperature sensor is presented. The sensor has a linear response versus temperature at a fixed bend radius, with a sensitivity of 8.2 ∙ 10−4(ºC)−1 〖8.2.10〗^(-4) 〖(°C) 〗^(-1) and a 8% non-linearity full scale error. The sensor system uses the power variation between two discrete wavelengths for auto reference purposes. An analysis for selecting operation wavelengths has been carried out in order to optimize the response of the sensor. The proposed sensor can be used in harsh environment and has a low-costThis work has been sponsored by the Spanish Ministry of Economía y Competitividad under grant TEC2012-37983-C03-02.Publicad

Experimental test of polymer optical fiber temperature sensor on different surrounding media

The proceeding at: 22nd International Conference on Plastic Optical Fibers (POF 2013), took place in 2013 September,11-13, in Armação dos Buzios, Rio de Janeiro, (Brasil). The event Web site at: http://www.pof2013.org.br/ .Influence of external media on a fiber-optic temperature sensor based on a macro-bend multimode Polymer Optical Fiber (POF) is analyzed. The sensor has a linear response with a sensitivity of 〖1.92.10〗^(-3) 〖(°C) 〗^(-1) at a fixed bend radius. 2.4 times sensitivity variations for different surrounding media are reported.This work has been sponsored by the Ministerio de Economía y Competitividad (TEC2012-37983-C03-02) & (TEC2012-37983-C03-01), Ministerio de Educación, Cultura y Deportes (PRX12/00007) y Comunidad de Madrid FACTOTEM-2/2010/00068/001.Publicad

Strain sensing based on radiative emission-absorption mechanism using dye-doped polymer optical fiber

A stress sensor based on a dye-doped polymeric optical fiber is able to detect stress by simple comparison of two luminescence peaks from a pair of energy transfer organic dyes. Coumarin 540A (donor) and Rhodamine 6G (acceptor) were doped in the core and cladding of the fiber, respectively. For various laser wavelengths, the change in the near-field pattern and visible emission spectrum upon variation in the fiber bending diameter was evaluated. From a comparison with a low-numerical-aperture fiber, it is shown that the sensitivity of the sensor is controllable by optimization of the waveguide parameters

Polymer Optical Fiber Temperature Sensor With Dual-Wavelength Compensation of Power Fluctuations

The design and development of a plastic optical fiber macrobend temperature sensor is presented. The sensor can operate in a temperature range from -55 to 70 degrees C and has a linear response versus temperature with a sensitivity of 8.95.10(-4) degrees C-1. The sensor system uses the ratio of transmittance at two wavelengths to implement a self-referencing technique in order to avoid undesirable power fluctuations influence. The transmittance ratio precision is 0.1%. An analysis has been developed to find the two wavelengths which ratio offers the highest linearity and sensitivity response. Experimental results are successfully compared with theoretical approaches.This work was supported by the Spanish Ministry of Economía y Competitividad and Madrid region under Grants TEC2012–37983-C03–02, P2013/MIT-2790.Publicad

Polymer Optical Fiber Plantar Pressure Sensors: Design and Validation

The proper measurement of plantar pressure during gait is critical for the clinical diagnosis of foot problems. Force platforms and wearable devices have been developed to study gait patterns during walking or running. However, these devices are often expensive, cumbersome, or have boundary constraints that limit the participant’s motions. Recent advancements in the quality of plastic optical fiber (POF) have made it possible to manufacture a low-cost bend sensor with a novel design for use in plantar pressure monitoring. An intensity-based POF bend sensor is not only lightweight, non-invasive, and easy to construct, but it also produces a signal that requires almost no processing. In this work, we have designed, fabricated, and characterized a novel intensity POF sensor to detect the force applied by the human foot and measure the gait pattern. The sensors were put through a series of dynamic and static tests to determine their measurement range, sensitivity, and linearity, and their response was compared to that of two different commercial force sensors, including piezo resistive sensors and a clinical force platform. The results suggest that this novel POF bend sensor can be used in a wide range of applications, given its low cost and non-invasive nature. Feedback walking monitoring for ulcer prevention or sports performance could be just one of those applications.This research was partially funded by Research and Innovation Programme from Community of Madrid SINFOTON2-CM (S2018/NMT-4326), and by FSE/FEDER funds, Spanish Research Agency under grant RTI2018-094669-B-C32, Spanish Ministry of Innovation and Universities under grant FJCI-2017-31677

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

Development of Fiber Bend Loss Edge Filter

This PhD thesis addresses several aspects of macrobending loss in single-mode optical fibers. The context for the work is the development of an edge filter for a rapid wavelength measurement system. Based on scalar approximation theory and the beam propagation method, a simulation platform is developed and used to predict the macrobending loss of singlemode fiber with single or multiple coating layers. A single-mode step index fiber macrobending loss edge filter is investigated theoretically in terms of baseline loss, discrimination range and polarization dependent loss (PDL). The theoretical analysis is supported by a range of experimental investigations and results. The bend loss characteristics of a conventional SMF28 based edge filter are investigated. The bend loss characteristics of a high bend loss fiber based edge filter are also investigated for comparison. It is shown that while the high-bend loss fiber based filter requires significantly fewer bend turns and exhibits a lower PDL, temperature dependence can be a major issue. A fiber selection method, specifically for an edge filter application, is reported and using this method a fiber is selected for a fiber bend loss edge filter that shows significantly improved spectral response (measured baseline loss is 5.09 dB and discrimination range is 17.42 dB) coupled to a lower average PDL and simpler fabrication technique. A theoretical model for macrobending-induced temperature dependent loss (TDL) for a fiber with dual coating layers is presented, with good agreement demonstrated between theoretical calculations and experimental results. The impact of temperature on two examples of an all-fiber based edge filter is also investigated theoretically and experimentally and using the developed model, it is shown that it is possible to predict the impact of temperature variations on an all-fiber based edge filter. The effect of temperature on polarization dependent loss is presented theoretically and experimentally as well. The impact of fiber manufacturing tolerances is also investigated and it is shown that variations in the numerical aperture and fiber core radius can have significant impact on the spectral response of an edge filter. A simple bend radius tuning technique is proposed to mitigate the effect of fiber manufacturing tolerances. A complete methodology for the design of a fiber based edge filter is presented, starting with the task of selecting suitable fibers and then considering the design of a fiber bending loss edge filter. Through the comparison of the performances of two previously developed types of fiber edge filters, as an example, a Corning SMF28e fiber with 900 μm jacket is selected as a tradeoff between SMF28 and 1060XP fiber and an edge filter design is undertaken. Finally, a subsidiary objective of this thesis is to explore novel applications for macrobending fiber based optical sensing devices. In this context, a macrobending fiber based refractometer sensor is studied theoretically, and a new theoretical model based on a 3-dimensional full-vectorial finite difference beam propagation method for accurately predicting the fiber bending loss is also presented

Development of Novel Fiber Optic Humidity Sensors and Their Derived Applications

The main focus of this thesis is on the design and development of novel fiber optic devices for relative humidity (RH) sensing with emphasis on high sensitivity, a wide humidity range, low temperature dependence, fast response time and good stability.Novel RH sensors based on fiber bends are fabricated by coating the surface of the buffer stripped bent fiber with selected hygroscopic materials such as Polyethylene oxide or Agarose. It is shown that the Polyethylene oxide coated device has a high sensitivity in a narrow RH range while the Agarose coated fiber bend shows a linear RH sensitivity in a wide RH range. Both of these sensors demonstrate a fast response (in the order of milliseconds) to RH variations. The limitations of fiber bend based humidity sensors are also discussed in the thesis. A novel RH sensor based on a reflection type photonic crystal fiber interferometer (PCFI) is presented which does not rely on the use of any hygroscopic material. The operating principle of a PCFI sensor based on the adsorption and desorption of water vapour at the silica-air interface within the PCF capillaries is discussed. The demonstrated sensor shows a good RH sensitivity in the higher RH range. Furthermore this RH sensor is almost temperature independent and can also be used in a high temperature and high pressure environment for humidity sensing.In order to improve the sensitivity of a reflection type PCFI over a wider RH range an alternative sensor is developed by infiltrating the microholes of the PCF with the hygroscopic material Agarose. The demonstrated novel sensor has a good sensitivity, a fast response time and a compact size. The temperature dependence of the device is also investigated. A novel hybrid device based on Agarose infiltrated PCFI interacting with a fiber Bragg grating is also presented which can simultaneously measure RH and temperature.A novel RH sensor based on a transmission type photonic crystal fiber interferometer coated with Agarose is also presented and discussed. This structure is used to study the effect of Agarose coating thickness in such a sensor on the RH sensitivity. It is demonstrated that the RH sensitivity of the sensor has a significant dependence on the thickness of the coating. An experimental method is also demonstrated to select an optimum coating thickness to achieve the highest sensitivity for a given RH sensing range. The sensor with the highest demonstrated sensitivity shows a linear response in the RH ranges of 40-80 % and 80-95 % with a sensitivity of 0.57 nm/%RH and 1.43 nm/%RH respectively.Finally, a comparison of the four RH sensing devices is presented, based on their size, operating range, RH sensitivity, temperature dependence and response time, in the context of selecting suitable devices for end-user applications. Two examples of applications are presented: dew sensing and breathing monitoring. The reflection type PCFI which does not use any hygroscopic material is selected for dew sensing and the dew response of the device is presented and discussed. Finally a novel breathing sensor based on the Agarose infiltrated PCFI is developed, which due to its immunity to interference from electric and magnetic fields, is suitable for breath monitoring of patients during medical procedures such as a magnetic resonance imaging scan

Optical Bend Sensor Based on Eccentrically Micro-Structured Multimode Polymer Optical Fibers

We report on a novel bend sensor with high flexibility and elasticity based on Bragg grating structures in polymer optical fibers to detect bending for the measurement of movement. The concept is very simple and relies on the inscription of eccentrical Bragg gratings into multimode graded-index polymer optical fibers via contact exposure with a krypton fluoride excimer laser in the ultraviolet region and an optimized phase mask. Depending on the fiber deformation, the lattice constant of the inscribed Bragg grating is strained or compressed due to its position relative to the fiber core. This in turn results in a specific shift of the Bragg wavelength of up to 1.3 nm to the red or blue wavelength region, respectively, which is sufficiently large to be reliably detected. Therefore, as proof of principle, deformation along one axis can be observed with a single Bragg grating with a maximum sensitivity of up to 65 pm/m−1 . Moreover, multiple Bragg gratings inscribed into the same polymer optical fiber at different positions around the fiber axis allow to determine the shape deformation of the fiber relative to a reference frame with similar accuracy. Consequently, this technology could form the basis for new applications in the areas of medical diagnostics, robotics or augmented reality, which are lacking affordable sensor systems to date