Open Access
Brilloun optical time domain analysis sensor assisted by a Brillouin distributed amplifier
(SPIE, 2015) Urricelqui Polvorinos, Javier; Sagüés García, Mikel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We demonstrate the extension of the measurement range of Brillouin optical time-domain analysis (BOTDA) sensors using a distributed Brillouin amplifier (DBA). The technique is based on injecting a DBA pump wave in the fiber to generate an additional Brillouin interaction that amplifies the BOTDA pump pulses. Furthermore, the differential pulse-width pair method is used to counteract the detrimental effects of the DBA amplification on the temporal shape of the pulses. Experimental proof-of-concept results in a 50-km fiber link demonstrate full compensation of the fiber’s attenuation with no penalty on the signal-to-noise ratio of the detected probe wave.
Open Access
Distributed vibration sensing based on optical vector network analysis
(IEEE, 2024-10-28) Loayssa Lara, Alayn; Vallifuoco, Raffaele; Zahoor, Rizwan; Zeni, Luigi; Sagüés García, Mikel; Minardo, Aldo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We introduce a novel method for distributed vibration sensing based on extracting the time-domain Rayleigh impulse response of an optical fiber from optical vector network analysis measurements. The optical-frequency-domain transfer function of the fiber is first measured, and then inverse Fourier transformed to provide the bandpass optical time-domain impulse response. Another relevant feature of the technique is that it enables excitation demodulation using the optical frequency dependence of the Rayleigh backscatter signal from the optical fiber, the so-called Rayleigh signature. This is the simplest method to obtain fully linear quantitative measurements of local changes in the strain or temperature experienced by the fiber and it is inherently free from signal fading impairments. Furthermore, the implementation of the technique uses a simple setup based on double-sideband modulation of a laser, self-homodyne detection with an optical hybrid, and narrow-bandwidth electrical signal acquisition and processing. We present proof-of-concept experiments to demonstrate the operation of the method with the measurement of dynamic strain and temperature perturbations in a 115-m optical sensing fiber with 16-cm spatial resolution and a sensitivity of 59 nHz. This sensing technique has the potential to provide high-sensitivity distributed measurements of tens-of-hertz excitations in hundreds-of-meters fibers, with centimeter spatial resolution. Therefore, it can become a valuable tool for structural health monitoring in application fields such as aerospace, marine, or civil engineering.
Open Access
Overcoming non-local effects and Brillouin threshold limitations in Brillouin distributed sensors
(SPIE, 2015) Urricelqui Polvorinos, Javier; Ruiz Lombera, Rubén; Sagüés García, Mikel; Mirapeix, Jesús; López Higuera, José Miguel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
We demonstrate, for the first time to our knowledge, a Brillouin optical time domain analysis sensor that is able to operate with a probe power larger than the Brillouin threshold of the deployed sensing fiber and that is free from detrimental non-local effects. The technique is based on a dual-probe-sideband setup in which a frequency modulation of the probes waves along the fiber is introduced. This makes the frequency of maximum interaction between pump and probes to vary along the fiber, thus mitigating the pump pulse depletion and making it possible to use very large probe power, which brings an improved signal-to-noise ratio in detection.
Open Access
Cost-effective Brillouin optical time-domain analysis sensor using a single optical source and passive optical filtering
(Hindawi Publishing Corporation, 2016) Iribas Pardo, Haritz; Urricelqui Polvorinos, Javier; Mariñelarena Ollacarizqueta, Jon; Sagüés García, Mikel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We present a simplified configuration for distributed Brillouin optical time-domain analysis sensors that aims to reduce the cost of the sensor by reducing the number of components required for the generation of the two optical waves involved in the sensing process. Te technique is based on obtaining the pump and probe waves by passive optical filtering of the spectral components generated in a single optical source that is driven by a pulsed RF signal. Te optical source is a compact laser with integrated electroabsorption modulator and the optical filters are based on fiber Bragg gratings. Proof-of-concept experiments demonstrate 1m spatial resolution over a 20km sensing fiber with a 0.9MHz precision in the measurement of the Brillouin frequency shiſt, a performance similar to that of much more complex setups. Furthermore, we discuss the factors limiting the sensor performance, which are basically related to residual spectral components in the filtering process.
Open Access
Overcoming non-local effects and Brillouin threshold limitations in Brillouin optical time domain sensors
(IEEE, 2015) Ruiz Lombera, Rubén; Urricelqui Polvorinos, Javier; Sagüés García, Mikel; Mirapeix, Jesús; López Higuera, José Miguel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We demonstrate, for the first time to our knowledge, a Brillouin optical time domain analysis (BOTDA) sensor that is able to operate with a probe power larger than the Brillouin threshold of the deployed sensing fiber and that is free from detrimental non-local effects. The technique is based on a dual-probe-sideband setup in which an optical frequency modulation of the probe waves along the fiber is introduced. This makes the optical frequency of the Brillouin interactions induced by each probe wave on the pump to vary along the fiber so that two broadband Brillouin gain and loss spectra that perfectly compensate are created. As a consequence, the pulse spectral components remain undistorted avoiding non-local effects. Therefore, a very large probe power can be injected, which improves the signal-to-noise ratio in detection for long-range BOTDA. Moreover, the probe power can even exceed the Brillouin threshold limit due to their frequency modulation, which reduces the effective amplification of spontaneous Brillouin scattering in the fiber. Experiments demonstrate the technique in a 50-km sensing link in which 8 dBm of probe power is injected.
Open Access
Monitorización de deformaciones y temperaturas en la estructura de un túnel artificial de alta velocidad mediante sensores ópticos puntuales, de longitud y distribuidos
(CSIC, 2015) Torres, B.; Payá Zaforteza, I.; Barrera, D.; Alvarado, Y. A.; Calderón, P. A.; Loayssa Lara, Alayn; Sagüés García, Mikel; Zornoza Indart, Ander; Sales, S.; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
La monitorización de estructuras es una rama de la ingeniería estructural que está captando mucha atención actualmente. Las deformaciones y temperaturas son, habitualmente, los parámetros monitorizados porque son los que mejor representan el comportamiento estructural. De todos los tipos de sensores existentes, los basados en fibra óptica resultan especialmente interesantes debido a sus ventajas comparativas sobre los sensores convencionales. En este artículo se presentan los trabajos de monitorización de la estructura de un túnel artificial de Alta Velocidad construido en Mogente (España) mediante tres tipos de sensores ópticos desarrollados por los autores. Los resultados de los sensores se comparan con los proporcionados por un modelo teórico de elementos finitos. Esta comparación confirma que los sensores reproducen notablemente bien la pauta general de comportamiento de la estructura, incluso con pequeños niveles de deformación (5µε). Por último, el artículo discute el comportamiento de los sensores, sus mediciones y sus campos de aplicación.
Open Access
Egituren egoeraren monitorizaziorako zuntz optikoan oinarritutako sentsore sinplifikatua
(Udako Euskal Unibertsitatea, 2015) Iribas Pardo, Haritz; Sagüés García, Mikel; Mariñelarena Ollacarizqueta, Jon; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Brillouin hedatuko denbora eremu optikoaren analisian (BOTDA) oinarritutako sentsoreak, estruktura handien (100 km luzerako estrukturak) deformazioa eta tenperatura neurtzeko gaitasuna dute. Lan honetan, BOTDA konfigurazio sinplifikatua aurkezten dugu. Erabilitako konfigurazioaren helburua sentsorearen prezioa murriztea da, detekzio prozesuan parte hartzen duten seinale optikoen sortze prozesua sinplifikatuz. Proposatutako teknika hau, iturri optiko bati irrati-maiztasun (IM) pultsu modulatu bat aplikatuz sortutako osagai espektralen iragazketa optiko pasiboan oinarritzen da. Laborategiko esperimentuek frogatzen dute tenperatura hedatuko neurriak 1,1 metroko erresoluzioarekin 5 km zuntz optikoan zehar
Open Access
Long-range and high-resolution traffic monitoring based on pulse-compression DAS and advanced vehicle tracking algorithm
(Optica Publishing Group, 2022) Corera Orzanco, Íñigo; Piñeiro Ben, Enrique; Navallas Irujo, Javier; Sagüés García, Mikel; Loayssa Lara, Alayn; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
We demonstrate traffic monitoring over tens of kilometres of road using an enhanced distributed acoustic sensing system based on optical pulse compression and a novel transformed-domain-based processing scheme with enhanced vehicle detection and tracking capabilities.
Open Access
Method to use transport microsimulation models to create synthetic distributed acoustic sensing datasets
(MDPI, 2025-05-07) Robles Urquijo, Ignacio; Benavente, Juan; Blanco García, Javier; Diego González, Pelayo; Loayssa Lara, Alayn; Sagüés García, Mikel; Rodríguez Cobo, Luis; Cobo, Adolfo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
This research introduces a new method for creating synthetic Distributed Acoustic Sensing (DAS) datasets from transport microsimulation models. The process involves modeling detailed vehicle interactions, trajectories, and characteristics from the PTV VISSIM transport microsimulation tool. It then applies the Flamant-Boussinesq approximation to simulate the resulting ground deformation detected by virtual fiber-optic cables. These synthetic DAS signals serve as large-scale, scenario-controlled, labeled datasets on training machine learning models for various transport applications. We demonstrate this by training several U-Net convolutional neural networks to enhance spatial resolution (reducing it to half the original gauge length), filtering traffic signals by vehicle direction, and simulating the effects of alternative cable layouts. The methodology is tested using simulations of real road scenarios, featuring a fiber-optic cable buried along the westbound shoulder with sections deviating from the roadside. The U-Net models, trained solely on synthetic data, showed promising performance (e.g., validation MSE down to 0.0015 for directional filtering) and improved the detectability of faint signals, like bicycles among heavy vehicles, when applied to real DAS measurements from the test site. This framework uniquely integrates detailed traffic modeling with DAS physics, providing a novel tool to develop and evaluate DAS signal processing techniques, optimize cable layout deployments, and advance DAS applications in complex transportation monitoring scenarios. Creating such a procedure offers significant potential for advancing the application of DAS in transportation monitoring and smart city initiatives.
Open Access
Distributed strain sensing with large dynamic range based on two-wavelength phase-sensitive OTDR
(Optica Publishing Group, 2020) Piñeiro Ben, Enrique; Sagüés García, Mikel; Mompó Roselló, Juan José; Eyal, Avishay; Loayssa Lara, Alayn; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
We demonstrate the use of two-wavelengths to enhance the dynamic range in phase-sensitive OTDR vibration sensors. The system overcomes the phase wrapping con- strains by the synthesis of an equivalent wavelength measurement.