Open Access
Characterization of a hybrid Fabry-Pérot Cavity based on a four-bridge double-Y-shape-core microstructured fiber
(SPIE, 2014-06-02) Rodrigues Pinto, Ana Margarida; López Aldaba, Aitor; López-Amo Sáinz, Manuel; Frazão, Orlando; Santos, José Luís; Baptista, José Manuel; Baierl, Hardy; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC
In this work, a hybrid Fabry-Perot interferometer based on a novel four-bridge microstructured fiber is presented and characterized. The characterization of this cavity is performed in the L-band using two different instruments: an optical spectrum analyzer and an optical backscatter reflectometer. The Fabry-Perot output signal presents linear variation with temperature changes (sensitivity 9.8-11.9 pm/ºC), variation with the polarization states of light and high stability.
Open Access
High-resolution absolute-distance measurements using multiple-tunable fiber Bragg gratings
(SPIE, 2004-06-09) Luquin Rodríguez, Elena; Frazão, Orlando; Ferreira, Luis Alberto; Araújo, Francisco Moita; López-Amo Sáinz, Manuel; Santos, José Luís; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
We present and demonstrate a high-resolution absolute-distance measurement system based on multiple-wavelength interferometry. The information on a cavity length is obtained by sampling a fringe of its spectral response at different wavelengths. This is achieved by simultaneously tuning multiple fiber Bragg gratings. For a two wavelength system, an unambiguous measurement range of 262 tm was obtained with a resolution of 14.3 nm.
Open Access
250 km ultra long remote sensor system based on a fiber loop mirror interrogated by an OTDR
(Optical Society of America, 2011) Bravo Acha, Mikel; Baptista, José Manuel; Santos, José Luís; López-Amo Sáinz, Manuel; Frazão, Orlando; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
A 253 km ultra long remote displacement sensor system based on a fiber loop mirror interrogated by a commercial OTDR is proposed and experimentally demonstrated. The use of a fiber loop mirror increases the signal to noise ratio allowing the system to interrogate sensors placed 253 km away from the monitoring system without using any optical amplification. The displacement sensor was based on a long period grating spliced inside of the loop mirror, which modifies the mirror reflectivity accordingly to the applied displacement.
Open Access
Control of the strain sensitivity using a suspended core photonic crystal fiber sensing head
(SPIE, 2014-06-02) Rota Rodrigo, Sergio; López-Amo Sáinz, Manuel; Kobelke, J.; Schuster, K.; Santos, José Luís; Frazão, Orlando; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work a strain sensor based on a suspended core fiber is proposed. The sensor comprises a suspended core PCF between SMFs and is based on the multimode interference generated in these transitions. A strain sensitivity study for different sensing heads and stage separation lengths was carried out showing a sensitivity of -2.42 pm/με for the best case. Also the sensing head was tested for curvature and temperature, showing in the first case that it is insensitive to curvature effects, and secondly, that for small sensor lengths it was insensitive to temperature variations.
Open Access
ECOAL project: delivering solutions for integrated monitoring of coal-related fires supported on optical fiber sensing technology
(MDPI, 2017) Ribeiro, Joana; Viveiros, Duarte; Ferreira, João; López Gil, Alexia; Domínguez López, Alejandro; Martins, Hugo F.; Pérez Herrera, Rosa Ana; López Aldaba, Aitor; Duarte, Lia; Rodrigues Pinto, Ana Margarida; Martín López, Sonia; Baierl, Hardy; Jamier, Raphael; Rougier, Sébastien; Auguste, Jean-Louis; Teodoro, Ana Cláudia; Gonçalves, José Alberto; Esteban, Óscar; Santos, José Luís; Roy, Philippe; López-Amo Sáinz, Manuel; González Herráez, Miguel; Baptista, José Manuel; Flores, Deolinda; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
The combustion of coal wastes resulting from mining is of particular environmental concern, and the importance of proper management involving real-time assessment of their status and identification of probable evolution scenarios is recognized. Continuous monitoring of the combustion temperature and emission levels of certain gases allows for the possibility of planning corrective actions to minimize their negative impact on the surroundings. Optical fiber technology is well suited to this purpose and here we describe the main attributes and results obtained from a fiber optic sensing system projected to gather data on distributed temperature and gas emissions in these harsh environments.
Open Access
Experimental and numerical characterization of a hybrid Fabry-Perot cavity for temperature sensing
(MDPI, 2015) López Aldaba, Aitor; Rodrigues Pinto, Ana Margarida; López-Amo Sáinz, Manuel; Frazão, Orlando; Santos, José Luís; Baptista, José Manuel; Baierl, Hardy; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
A hybrid Fabry-Pérot cavity sensing head based on a four-bridge microstructured fiber is characterized for temperature sensing. The characterization of this cavity is performed numerically and experimentally in the L-band. The sensing head output signal presents a linear variation with temperature changes, showing a sensitivity of 12.5 pm/°C. Moreover, this Fabry-Pérot cavity exhibits good sensitivity to polarization changes and high stability over time.
Open Access
Micro-displacement sensor combined with a fiber ring interrogated by an optical time-domain reflectometer
(IEEE, 2014) Bravo Acha, Mikel; Baptista, José Manuel; Santos, José Luís; López-Amo Sáinz, Manuel; Frazão, Orlando; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
A micro-displacement sensing head based on two aligned cleaved fibers inserted into an optical fiber ring and interrogated by an OTDR is presented. The sensor configuration is characterized for measuring both longitudinal and axial microdisplacement, showing a sensitivity of 0.07 dB/mm and 2.67 dB/mm for longitudinal and axial micro-displacement, respectively. A multiplexing system using two of these configurations is also studied.
Open Access
Micro-displacement sensor based on a hollow-core photonic crystal fiber
(MDPI, 2012) Rodrigues Pinto, Ana Margarida; López-Amo Sáinz, Manuel; Baptista, José Manuel; Santos, José Luís; Frazão, Orlando; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
A sensing head based on a hollow-core photonic crystal fiber for in-reflection measurement of micro-displacements is presented. The sensing structure takes advantage of the multimodal behavior of a short segment of hollow-core photonic crystal fiber in-reflection, being spliced to a single mode fiber at its other end. A modal interferometer is obtained when the sensing head is close to a mirror, through which displacement is measured.
Open Access
Multiwavelength Raman fiber lasers using Hi-Bi photonic crystal fiber loop mirrors combined with random cavities
(IEEE / OSA, 2011) Rodrigues Pinto, Ana Margarida; Frazão, Orlando; Santos, José Luís; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
Different multiwavelength Raman fiber lasers based on a hybrid cavity set-up are proposed. The lasing schemes are based in highly birefringent photonic crystal fiber loop mirrors combined with random cavities. The Hi-Bi PCF loop mirrors are characterized by an interferometric output; whereas the random mirrors are created by cooperative Rayleigh scattering due to Raman gain. This configuration allows suppression of Rayleigh associated noise growth, while taking advantage of it as an active part of the laser cavity, enhancing the achievable gain. The proposed fiber lasers present stable operation at room temperature although different output maxima and shapes depending on the fiber loop mirror/random mirror combination.
Open Access
Simultaneous strain and temperature measure based on a single suspended core photonic crystal fiber
(SPIE, 2014-06-02) Rota Rodrigo, Sergio; López-Amo Sáinz, Manuel; Kobelke, J.; Schuster, K.; Santos, José Luís; Frazão, Orlando; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work a simultaneous strain and temperature sensor based on a suspended core fiber is proposed. The sensor comprises a 3mm suspended core PCF between SMFs and is based on the combination of two multimodal interferences with different frequency fringe patterns. The interference of the both signal has different sensitivity responses to strain and temperature. Thought a low-pass frequency filtering of the detected spectrum, the wavelength shift of the two interferences can be measured allowing the discrimination of strain and temperature simultaneously. The resolutions of this sensor are 0.45 ºC and 4.02 με.