Open Access
Highly sensitive sensor for measuring material thermal expansion using a ring laser
(IEEE, 2023) Díaz Lucas, Silvia; Fuentes Lorenzo, Omar; Torres Betancourt, Angie Tatiana; Corres Sanz, Jesús María; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A new thermal expansion sensor is presented in this letter. It combines an interferometric fiber sensor and an erbium-doped fiber ring laser as the light source. The sensor consists of a combination of single-mode, hollow-core, and no-core mirror fibers. The sensor was tested on two different types of based metal, such as aluminum and steel, giving sensitivities as high as 38.7 and 5.75 nm/°C, respectively, showing good performance.
Open Access
Resonance-based optical gas sensors
(IEEE, 2025-07-02) Gallego Martínez, Elieser Ernesto; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Gas sensors play a critical role in numerous human activities. Their necessity continues to grow across diverse fields as technological advancements drive demand for precision agriculture and bioengineering among other applications. Among existing sensor technologies, optical gas sensors stand out due to their ability to operate remotely in high-risk environments while remaining unaffected by electromagnetic interference. Resonance-based optical sensors offer targeted gas detection through the functionalization of their sensitive surfaces. This work focuses on reviewing the state of the art in resonance-based optical gas sensors (ROGSs), addressing their fundamental principles, recent advances in fabrication processes, waveguide designs, and materials employed both for resonance generation and as sensitive coatings. In addition, the review examines achieved sensitivity, emerging applications, and key developments in the field, including those efforts on improving ROGS performances by means of artificial intelligence techniques. The study encompasses optical sensors leveraging surface plasmon resonance, lossy mode resonance, and hyperbolic mode resonance¿the latter representing a notable breakthrough in recent years as a particular case of Bloch surface waves.
Open Access
UV light detection with side polished CYTOP fiber
(IEEE, 2023) Ayechu Abendaño, Ada; Santano Rivero, Desiree; López Vargas, Juan David; Matías Maestro, Ignacio; Del Villar, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Cyclic transparent optical polymer (CYTOP) fiber, used mainly in strain detection and refractive index characterization of liquids, can be polished for the detection of ultraviolet (UV) light radiation. The study investigates the transmission spectra of CYTOP fiber exposed to different intensities of UV light, demonstrating a linear relationship. A simplified system using a single wavelength, i.e., 395 nm, shows real-time performance of the sensor in a range from 1 to 15 mW. The results reveal the potential of CYTOP fiber as a UV sensor with a sensitivity of 0.65%/mW and a limit of detection of 0.3 mW, offering implications for monitoring UV radiation exposure and related health risks. In addition, the effect of the UV light was also observed at longer wavelengths with a lower intensity variation, which suggests that CYTOP fiber could be used for transmitting the UV radiation detection in telecommunications bands.
Open Access
Lossy mode resonance-based sensors in planar configuration: a review
(IEEE, 2023) Matías Maestro, Ignacio; Del Villar, Ignacio; Corres Sanz, Jesús María; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Lossy mode resonance (LMR)-based sensors have attracted much interest during the last decade in the domain of optical fiber (OF). Here, it is shown that the progress made in the transfer of this technology to planar waveguides (PWs) with different sensing applications such as environmental sensors and biosensors. In addition, the inherent advantages in terms of robustness, simplicity, and easiness to generate novel complex structures are discussed.
Open Access
Planar-waveguide-lmr-based sensors: engineering the depth of characteristic curves
(IEEE, 2023) Shrivastav, Anand M.; Del Villar, Ignacio; Ascorbe Muruzabal, Joaquín; Corres Sanz, Jesús María; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Lossy mode resonance (LMR)-based sensors have been proven as one of the exponentially growing research fields since the last decade. These sensors have demonstrated their capabilities in the detection of several physical, chemical, and biological entities, such as refractive index, humidity, gases, enzymes, etc. Conventionally, LMR-based sensors are developed using optical fiber as the sensing platform, but to increase the broad range of applications and better tenability, planar waveguide substrates for LMR realization have been introduced in the last few years. This provides a greater degree of freedom for the sensor design such as tunability in substrate thickness, material, and better surface immobilization. The current study focuses on evaluating the effect of substrate thickness on LMR-based optical sensors to achieve higher sensing performance. For experiments, 150-μm-thick glass coverslips are used as the thin planer substrate, which is then coated with a few nanometers thick LMR-supported SnO 2 layer using the dc sputtering method. Furthermore, to monitor the effect of the changing substrate thickness, the width of the glass coverslip is reduced through the chemical etching process using the 40% HF solution, and simultaneously, the changes in LMR spectra are analyzed. The study shows that the depth of LMR curves strongly depend on the thickness of the waveguide providing LMRs with lower substrate thickness possesses higher depth. Greater depth in LMR curves is a crucial factor in identifying the minimum transmission wavelength of resonance, making it easier to track and detect the targeted parameter. This characteristic greatly enhances the applicability of LMR-based sensors in industrial applications.
Open Access
Quantum dots coatings inside photonic crystal fibers for temperature sensing
(IEEE, 2008-12-16) Arigita Lasheras, Jesús; Larrión Zabaleta, Beatriz; Bravo Larrea, Javier; Hernáez Sáenz de Zaitigui, Miguel; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Gobierno de Navarra / Nafarroako Gobernua
Temperature sensors based on Quantum Dots (QDs) nanofilms deposited on the inner holes of a Photonic Crystal Fiber (PCF) was created using the layer by layer electrostatic self-assembly method. The structure is based on a PCF fiber segment spliced between two Standard Multimode Fibers (MMF) of different diameters. The sensors showed a linear variation of the intensity and wavelength emission for a temperature range from -20 ºC to 70 ºC.
Open Access
Single-mode-multimode-single-mode fiber (SMS): exploring environmental sensing capabilities
(IEEE, 2024-08-16) Díaz Lucas, Silvia; Armendáriz Ballesteros, Mikel; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
In this paper, we study the environmental sensing capabilities of a Single-Mode-Multimode-Single-Mode (SMS) fiber in a simple low-cost configuration. SMS fibers exhibit sensitivity to temperature, humidity, refractive index and strain, making them suitable for numerous applications in telecommunications, environmental monitoring, and more. Experimental results demonstrate that the sensor achieves a maximum temperature sensitivity of 4.53 nm/°C. Additionally, SMS fibers can also work as humidity sensors by absorbing or releasing moisture, leading to variations in the refractive index. Monitoring these changes allows for precise humidity measurements, with a sensitivity of 0.1548 nm/%RH. Moreover, SMS fibers show a refractive index sensitivity of 39.65 nm/RIU and strain sensitivities as high as 1.062 nm/¿¿, indicating good performance.
Open Access
Printed optical waveguide temperature sensor with rhodamine-doped core
(IEEE, 2024-06-08) Dávila Galiana, Rebeca Beatriz; Matías Maestro, Ignacio; Zabala, Silvia; Socorro Leránoz, Abián Bentor; Rivero Fuente, Pedro J.; Corres Sanz, Jesús María; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua
This letter demonstrates the fabrication of a temperature optical sensor by printing the corresponding sensitive optical waveguide directly onto a flexible flat substrate. The printed waveguide was carried out using a coaxial needle and an electrohydrodynamic (EHD) machine. The fluorescent organic compound, rhodamine B, was used for doping the core of the printed waveguide as temperature sensible dye. The optical sensitive waveguide manufactured is compact, ensuring coupling with the input and output optical fibers. The response of the printed optical sensor was evaluated to temperature variations by measurement of both, the peak intensity and the wavelength of the fluorescence spectra. The experimental characteristic and sensitivity of the sensor were obtained.