Open Access
Phasorial differential pulse-width pair technique for long-range Brillouin optical time-domain analysis sensors
(Optical Society of America, 2014) 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 introduce a novel phasorial differential pulse width pair (PDPP) method for Brillouin optical time domain analysis (BOTDA) sensors that combines spatial resolution enhancement with increased tolerance to non local effects. It is based on the subtraction of the complex time domain traces supplied by a sensor configuration that uses a phase modulated probe wave and RF demodulation. The fundamentals of the technique are first described theoretically and using numerical simulation of the propagating waves. Then, proof of concept experiments demonstrate the measurement of the Brillouin frequency shift distribution over 50 km. The system is shown to withstand large variations of the pump power generated by its interaction with a powerful probe wave along the fiber; hence, highlighting the potential of the PDPP technique to increase the detected signal to noise ratio in long range BOTDA. Moreover, the PDPP is also shown to increase the measurement contrast by allowing the use of relatively long duration pulses while retaining 1 m spatial resolution.
Open Access
Medida de torsión en seguidores solares con sensores de fibra óptica
(SEDOPTICA, 2021) Leandro González, Daniel; Bravo Acha, Mikel; López-Amo Sáinz, Manuel; Loayssa Lara, Alayn; Júdez Colorado, Aitor; Mariñelarena Ollacarizqueta, Jon; Falcone Lanas, Francisco; Jiménez Romero, Sergio; Moriana García, Iñaki; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Gobierno de Navarra / Nafarroako Gobernua WINDSOLAR (0011-1365-2017-000122)
En este trabajo se ha monitorizado la torsión sufrida por una estructura de seguidores solares empleando sensores de fibra óptica. Estas medidas de campo se han obtenido con una red de sensores formada por 45 redes de difracción de Bragg en una huerta solar activa. Estos resultados, correlados con la velocidad y dirección del viento permitirían aumentar la eficiencia de los seguidores y ayudar a entender y prevenir efectos negativos relacionados con inestabilidades aeroelásticas.
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
Detrimental effects in Brillouin distributed sensors caused by EDFA transient
(Optical Society of America, 2017) Feng, Cheng; Iribas Pardo, Haritz; Mariñelarena Ollacarizqueta, Jon; Schneider, Thomas; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
We investigate the deleterious effect and the error in Brillouin optical time-domain analyzers induced by the combination of a low extinction ratio pulse generation with the transient behavior of erbium-doped fiber amplifiers.
Open Access
Synthesis of Brillouin frequency shift profiles to compensate non-local effects and Brillouin induced noise in BOTDA sensors
(Optical Society of America, 2014) 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 present a novel technique for Brillouin optical time domain analysis (BOTDA) sensors that simultaneously compensates non local effects and reduces Brillouin noise. The technique relies on the wavelength modulation of the optical source to modify the Brillouin interaction between probe and pump waves during their propagation. The resulting Brillouin distribution mimics the wavelength modulation, creating a virtual Brillouin frequency shift profile along the sensing fiber. The fundamentals of the technique are first described theoretically and using numerical simulations. Then, proof of concept experiments demonstrate the capabilities of the system to reduce large variations of the pump power resulting from the interaction with high probe powers and to decrease the Brillouin induced noise enhancing the signal to noise ratio (SNR) of the system. Furthermore, we show, for the first time to our knowledge, measurements of the Brillouin distribution using an injected optical power higher than the Brillouin threshold of the fiber.
Open Access
Brillouin optical time-domain analysis sensor assisted by Brillouin distributed amplification of pump pulses
(Optical Society of America, 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 and compensates optical fiber attenuation. This amplification does not introduce any significant noise to the BOTDA’s probe wave due to the inherent directionality of the Brillouin gain. Additionally, we deploy a differential pulse-width pair measurement method to avoid measurement errors due to the interplay between the self-phase modulation effect and the changes in the temporal shape of the pulses induced by the transient behavior of Brillouin gain. Experimental proof-of-concept results in a 50-km fiber link demonstrate full compensa- tion of the fiber’s attenuation with no penalty on the signal-to-noise ratio of the detected signal.
Open Access
Brillouin optical time-domain analysis sensor with pump pulse amplification
(Optical Society of America, 2016) Mompó Roselló, Juan José; Urricelqui Polvorinos, Javier; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We demonstrate a simple technique to provide conventional Brillouin optical time-domain analysis sensors with mitigation for pump pulse attenuation. The technique is based on operating the sensor in loss configuration so that energy is transferred from the probe wave to the pump pulse that becomes amplified as it counter-propagates with the probe wave. Furthermore, the optical frequency of the probe wave is modulated along the fiber so that the pump pulse experiences a flat total gain spectrum that equally amplifies all the spectral components of the pulse, hence, preventing distortion. This frequency modulation of the probe brings additional advantages because it provides increased tolerance to non-local effects and to spontaneous Brillouin scattering noise, so that a probe power above the Brillouin threshold of the fiber can be safely deployed, hence, increasing the signal-to-noise ratio of the measurement. The method is experimentally demonstrated in a 100-km fiber link, obtaining a measurement uncertainty of 1 MHz at the worst-contrast position.
Open Access
46-km-long Raman amplified hybrid double-bus network with point and distributed Brillouin sensors
(IEEE, 2012) Fernández Vallejo, Montserrat; Olier Aguado, David; Zornoza Indart, Ander; Pérez Herrera, Rosa Ana; Díaz Lucas, Silvia; Elosúa Aguado, César; Bariáin Aisa, Cándido; Loayssa Lara, Alayn; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
We experimentally demonstrate a 46-km hybrid network that combine point and distributed Brillouin sensors. The proposed sensor network multiplexes low-cost intensity point sensors based on fiber-optic tapers, which are able to measure vibrations in the 0.01 to 50 Hz frequency range. The sensor network with a double-bus is a low noise configuration, which offers a higher optical signal to noise ratio and dynamic range than a single-bus. Thus, the number of sensors to be multiplexed could increase or we could reach further distances. The system also deploys remote distributed Raman amplification to extend the sensing range.
Open Access
BOTDA measurements tolerant to non-local effects by using a phase-modulated probe wave and RF demodulation
(Optical Society of America, 2013) 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 a Brillouin optical time domain analysis sensor based on a phase modulated probe wave and RF demodulation that provides measurements tolerant to frequency dependent variations of the pump pulse power induced by non local effects. The tolerance to non local effects is based on the special characteristics of the detection process, which provides an RF phase shift signal that is largely independent of the Brillouin gain magnitude. Proof of concept experiments performed over a 20 km long fiber demonstrate that the measured RF phase shift spectrum remains unaltered for large frequency dependent deformations of the pump pulse power. Therefore, it allows the use of a higher optical power of the probe wave, which leads to an enhancement of the detected signal to noise ratio. This can be used to extend the sensing distance, to improve the accuracy of the Brillouin frequency shift measurements, and to reduce the measurement time.
Open Access
Second-order non-local effects mitigation in BOTDA sensors by tracking the BFS profile
(SPIE, 2017) Mompó Roselló, Juan José; Iribas Pardo, Haritz; Urricelqui Polvorinos, Javier; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
We demonstrate a technique to mitigate the residual second-order non-local effects in Brillouin optical time-domain analysis (BOTDA) sensors in which the Brillouin frequency shift (BFS) profile is not uniform along the fiber. It is based on adding a wavelength modulation to the probe wave that makes it track the average BFS found along its way. Using this method we are able to inject a total probe wave power of 15 dBm in a 120-km sensing fiber link, which, to the best of our knowledge, is the highest probe power ever demonstrated in a long-range BOTDA sensing fiber link. The enhancement in the detected signal-to-noise ratio brought by the use of such power provides 2-MHz BFS measurement precision at the end of the 120-km sensing link with 3-m spatial resolution, all without the need to resort to additional means such as the use of coding or Raman gain.