Person:
Díaz Herrera, Natalia

First Name

Natalia

Last Name

Díaz Herrera

URI

https://hdl.handle.net/20.500.14352/79985

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Óptica y Optometría

Department

Óptica

Area

Optica

Identifiers

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Search Results

Now showing 1 - 10 of 25

Sensing properties of asymmetric double-layer-covered tapered fibers
(Applied Optics, 2004) Bueno Guillén, Francisco Javier; Esteban Martínez, Óscar; Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; González Cano, Agustín
A novel, to our knowledge, device based on a tapered optical fiber with a double-layer deposition including a metallic media is presented, and its properties are studied. The main novelty of the device consists of the introduction of a dielectric layer, whereas the systems depicted in the literature are simply metal-coated tapered fibers. The presence of the dielectric layer permits one to tune the response of the device to the refractive index of the surrounding medium. We have proved the suitability of this scheme for refractive-index sensing by depicting two measurement modes, namely, total power attenuation and spectral transmittance.
Educational resources for physics 101 instruction with health science degrees
(2024) González Fernández, Verónica; González Cano, Agustín; Alda Serrano, Javier; Piedrahita Alonso, María Elena; Fernández Núñez, Sara; Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; Ares Santos, Laura; Orenes Plankova, Alexandra
In the present article, we present a comprehensive suite of educational resources and interactive exercises designed for initial Physics instruction targeted at students pursuing a Degree in Optics and Optometry. These materials have the potential to be adaptable and beneficial across various disciplines within the realm of Health Sciences. We begin by performing a preliminary analysis of the perceptions of older and new students, to develop an optimized teaching program. This consists of several workpackages aiming to increase the personal interest and involvement of the students, as well as the practical aspects regarding the subject. We include several experimental demonstrations and experiences done in the classroom. To reinforce the assimilation of most difficult concepts some educational videos are also recorded for the students.
Plasmonic sensor based on tapered optical fibers and magnetic fluids for measuring magnetic fields
(Sensors and actuators A - Physical, 2017) Rodriguez Schwendtner, E.; Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; González Cano, Agustín; Esteban Martínez, Óscar
We present a new sensor based on the combination of Surface Plasmon Resonance (SPR) with magneto-refractive materials. We use doubly-deposited uniform-waist tapered optical fibers (DLUWTs), that have shown their good performance and versatility as refractometers, and magnetic fluids as transducers to measure magnetic fields in an all-optical-fiber configuration. We experimentally show the feasibility of our approach, by demonstrating the physical principle of the device and characterizing the performance of the sensors, which show very good sensitivity and resolution. In this way, we propose a new field of development for SPR optical fiber sensors to extend the field of application of the plasmonics-based technologies.
Desarrollo de sensores de fibra óptica para el control "in-situ" de parámetros físicos del medio acuático
(2009) Díaz Herrera, Natalia; Navarrete Fernández, Mª Cruz; González Cano, Agustín
Este trabajo ha incorporado la tecnología de los sensores de fibra óptica a la determinación y control in-situ de parámetros físicos del medio acuático. Se han desarrollado y puesto a punto diversos sensores de fibra óptica para la determinación simultánea del grado de salinidad y la temperatura del agua, basados en efectos físicos diferentes a los de los sensores comerciles. Los sensores están basados enfibras estrechadas por fusión y estiramiento (tapers), y se diseñaron para explotar sus diferentes cualidades. Se ha caracterizado el comportamiento de tapers de cuello uniforme (QWT) respecto a sus dos características más importantes : la sensibilidad a cambios del índice de refracción esterior y fuerte dependencia con la geometría, mediante la elección de transductores que realzan dichos efectos. Se han ensayado dos propuestas de sensor de temperatura, la primera consistente en el depósito sobre un UWT de un material termocrómico, lofina, ya que es hidrófobo y cambia su absortancia con la temperatura. La segunda propuesta aprovecha la sensibilidad a cambios en la curvatura de los tapers, y consiste en la fijación de un UWT en el interior de un cilindro capilar. Se ha ensayado también uuna propuesta de sensor de índice de refracción, que aprovecha la gran sensibilidad de los tapers a cambios en el índice de refracción exterior, basado en la resonancia de plasmones superficiales al depositar un doble recubrimiento asimétrico (metal-dieléctrico) sobre un UWT. Asimismo, se han realizado diversas campañas de campo con el sensor desarrollado con anterioridad por el grupo investigador para la determinación in-situ del grado de salinidad, demostrando con éxito su uso en condiciones reales de medida en campo. Estos sensores son simples y de pequeño tamaño, herramientas transportables y de fácil manejo aptas para el uso in-situ en diferentes escenarios, incluyendo alta mar, plataforma costera y cuencas fluviales. [ABSTRACT]This work has incorporated the technology of fiber optic sensors to the determination and in-situ control of physical parameters of the marine environment. It has been developed and tuned up several fiber optic sensors for the simultaneous determination of the degree of salinity and water temperature, based on different physical effects to those that commercial sensors use. The sensors are based on tapered fibers fabricated by heating and stretching the fiber (tapers), and were designed to exploit their different features. It has been characterized the behaviour of uniform waist tapers (UWT) regarding their two most important features: the sensitivity to changes in the external the refractive index and the strong dependence on geometry, through the choice of the appropriate transducers that enhance these effects. Two proposals have been tested for a temperature sensor, the first consisting in a deposit of a thermochromic material, lophine, on a UWT because it is a hydrophobic material and its absorbance changes with temperature. The second proposal takes advantage of the sensitivity to changes in the curvature of the tapers, and consists in the fixation of a UWT in a capillar. It has been also tested a refractive index sensor, which takes advantage of the high sensitivity to changes in external refractive index of tapers, based on surface plasmon resonance due to the deposition of an asymmetric double layer (metal - dielectric) on a UWT. There has also been carried out several field measurement campaigns with the sensor developed previously by the research group for in-situ determination of the degree of salinity, which has successfully demonstrated the suitability of its use in real conditions of field measurements. These sensors are simple and small, easily transportable tools and suitable for in-situ measurements in different scenarios, including sea, river and coastal platform.
Microfiber as light source for exciting fluorescence in a polymer optical fiber
(Sensors and Actuators B - Chemical, 2016) Rodriguez Schwendtner, E.; Navarrete Fernández, María Cruz; Díaz Herrera, Natalia; Esteban Martínez, Óscar; González Cano, Agustín
We present a new technique for exciting and collecting fluorescence with all-fiber devices, consisting of two different tapered fibers, a microfiber used as illuminating source and a polymer optical fiber where a fluorophore has been deposited and where the fluorescence takes place. We depict the fabrication of the device, characterize its performance and show the feasibility of our approach, the good performance obtained and the possibility of using the flexibility of the illuminating fiber to increase this performance and the compactness of the device.
Improved performance of SPR sensors by a chemical etching of tapered optical fibers
(Optics and Lassers in Engineering, 2011) Díaz Herrera, Natalia; Esteban Martínez, Óscar; Navarrete Fernández, María Cruz; González Cano, Agustín; Benito Peña, María Elena; Orellana Moraleda, Guillermo
We present the results of a chemical attack on the optical fiber surface previous to the deposition of the double layer (metal plus dielectric) in Double-layer uniform-waist tapered fibers (DLUWTs) used for the development of SPR sensors. It is shown how this simple chemical treatment increases the roughness of the surface and permits improvement of the stability of the deposits and the general performance of the sensors. The obtained devices are robust and very compact, their sensitivity is good and repeatability of the measurements is remarkably increased. The procedure can be useful for any fiber-optic sensor.
A fibre-optic temperature sensor based on the deposition of a thermochromic material on an adiabatic taper
(Measurement Science and Technology, 2004) Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; Esteban Martínez, Óscar; González Cano, Agustín
A fibre-optic sensor has been developed for the measurement of temperature, especially of liquids. The device is conceived as part of an all-optical CTD probe for the control of the physical parameters of a marine medium. The dependence on temperature of the optical properties (specifically, absorbance) of a thermochromic material, namely lophine (2,4,5-triphenylimidazole), is the basis of the sensor. The sensor presents some significant differences with respect to other similar sensors proposed in the literature: the use of adiabatic, long, tapered optical fibres with adjustable geometric parameters; the use of LED illumination in the 800 nm range; improvements in the deposition technique, etc. The sensors show a linear behaviour over the desired temperature range, and their sensitivity is high. Also, the dependence of the response of the sensor with variations of the geometry of the tapers is discussed. Specifically, we have performed measurements with different diameters of the taper waist, and we show the dependence of the slope of the response curve with that parameter.
Surface plasmon resonance sensors based on uniform-waist tapered fibers in a reflective configuration
(Applied Optics, 2006) Esteban Martínez, Óscar; Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; González Cano, Agustín
We present a configuration for surface plasmon resonance sensors based on uniform-waist tapered optical fibers and reflective elements. Once the fiber is tapered fulfilling the adiabatic criterion, a multilayer including a metallic medium is asymmetrically deposited on the uniform waist of the fiber. This feature provides the resonant excitation of multiple surface plasma waves. In addition, a mirror is produced at the fiber tip by a chemical Tollens reaction. In this way, the sensor operates in a reflective mode, more convenient for dip probes. When these sensors are spectrally interrogated, a high sensitivity of 10^4 refractive index units per nanometer is attained. These devices can be advantageously used for any kind of chemical sensing and biosensing.
Selectivity of SPR fiber sensors in absorptive media: An experimental evaluation
(Sensors and Actuators B - Chemical, 2011) Navarrete Fernández, María Cruz; Díaz Herrera, Natalia; González Cano, Agustín; Esteban Martínez, Óscar; Leite, Ivo
Conventional surface plasmon resonance (SPR) fiber sensors show selective behavior when resonance wavelengths are tuned to absorption peaks of the surrounding medium, as it is experimentally shown and evaluated in this paper by using a doubly-deposited uniform-waist tapered optical fiber (DLUWT) and a dye as a test material. This behavior is clearly distinguishable from the usual response to nonabsorbing media and can be used to develop a new concept of SPR transducers. At the same time, the obtained results, which are in accordance with the theoretical predictions permit to increase the basic knowledge on surface plasma waves excitation in optical fibers.
Deposition of Graphene Oxide on an SPR Fiber Refractometer for Sensor Applications
(Sensors, 2023) Navarrete Fernández, María Cruz; Díaz Herrera, Natalia; González Cano, Agustín
Graphene-based materials have been increasingly incorporated to optical fiber plasmonic sensors due to the peculiar physical and chemical properties of these materials (hardness and flexibility, high electrical and thermal conductivity, and very good adsorption for many substances, etc.). In this paper, we theoretically and experimentally showed how the addition of graphene oxide (GO) to optical fiber refractometers permits the development of surface plasmon resonance (SPR) sensors with very good characteristics. We used doubly deposited uniform-waist tapered optical fibers (DLUWTs) as supporting structures because of their already proven good performance. The presence of GO as an effective third layer is useful to tune the wavelength of the resonances. In addition, the sensitivity was improved. We depict the procedures for the production of the devices and characterize the GO+DLUWTs produced in this way. We also showed how the experimental results are in agreement with the theoretical predictions and used these to estimate the thickness of deposited GO. Finally, we compared the performance of our sensors with other ones that have been recently reported, showing that our results are among the best reported. Using GO as the medium in contact with the analyte, in addition to the good overall performance of devices, permit consideration of this option as an interesting possibility for the future development of SPR-based fiber sensors.