Open Access
Real-time FFT analysis for interferometric sensors multiplexing
(IEEE / OSA, 2015) Leandro González, Daniel; Bravo Acha, Mikel; Ortigosa Cayetano, Amaia; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, a theoretical and experimental study of two interferometric sensor multiplexing schemes has been carried out by means of the fast Fourier transform (FFT) analysis. This work addresses one of the main drawbacks of photonic crystal fiber (PCF) sensors, that is, its multiplexing capability. Using a commercial optical interrogator combined with a simple FFT measurement technique, the simultaneous real-time monitoring of several PCF sensors is achieved. A theoretical analysis has been performed where simulations matched with the experimental results. For the experimental verification, highly birefringent (HiBi) fiber sections that operated as sensing elements were multiplexed and tested in two configurations. Due to the FFT analysis, both multiplexing schemes can be properly interrogated by monitoring the FFT phase change at the characteristic spatial-frequency of each sensor. For this purpose a commercial interrogator and a custom Matlab program were used for computing the FFT and for monitoring the FFT phase change in real-time (1 Hz).
Open Access
Random DFB fiber laser for remote (200 km) sensor monitoring using hybrid WDM/TDM
(IEEE, 2016) Leandro González, Daniel; Miguel Soto, Verónica de; Pérez Herrera, Rosa Ana; Bravo Acha, Mikel; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, a random distributed feedback fiber laser is proposed as a multiplexing scheme for ultralong range measurements (up to 200 km). Optical fiber sensors are time and wavelength multiplexed overcoming one of the main limitations of long-range sensing setups, which is their limited multiplexing capability. The direct modulation of the laser's cavity allows the interrogation of sensors by measuring the reflected power for different wavelengths and distances. Fiber Bragg gratings placed at different fiber locations and wavelengths have been interrogated in two different sensor networks. In addition, in order to improve the performance of the system, some features have been analyzed.
Open Access
Random fiber lasers: application to fiber optic sensors networks
(IEEE, 2017) López-Amo Sáinz, Manuel; Leandro González, Daniel; Miguel Soto, Verónica de; Bravo Acha, Mikel; Fernández Vallejo, Montserrat; Pérez Herrera, Rosa Ana; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
Recently, random mirrors have been proposed as a method to create fiber laser cavities. This kind of cavity is based on cooperative Rayleigh scattering, which is generated along a fiber due to the material inhomogeneities presented in that fiber. In this work, basics of Random fiber lasers and different demonstrated lasing sensors systems for interrogating arrays of optical fiber sensors are shown. These systems use different kinds of amplification and cavities schemes and can interrogate optical fiber sensors located up to 225 km away.
Open Access
Wavelength converter using a highly Er-doped optical fiber ring laser
(IOP Publishing, 2018) Pérez Herrera, Rosa Ana; López-Amo Sáinz, Manuel; Rodríguez, Luis; Ventura Rípodas, Daniel; López Higuera, José Miguel; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
This work presents an all-fiber wavelength converter based on a highly Er-doped fiber laser, which has been experimentally demonstrated. Frequencies from several kilohertz up to tens of gigahertz have been investigated. Making use of the gain competition in the amplifying medium, the wavelength conversion can be carried out over not only one lasing wavelength, but over several. These analyses have also been carried out for more than one all-fiber ring structure, demonstrating the viability of this wavelength converter. To the best of our knowledge, this is the first time an Er-doped fiber wavelength converter has been validated.
Open Access
Real time measuring system of multiple chemical parameters using microstructured optical fibers based sensors
(IEEE, 2018) López Aldaba, Aitor; López Torres, Diego; Elosúa Aguado, César; Arregui San Martín, Francisco Javier; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; López-Amo Sáinz, Manuel; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In this paper, a multiplexing system for simultaneous interrogation of optical fiber sensors which measure different parameters is presented and validated. The whole system has been tested with 6 different sensing heads with different purposes: one temperature sensing head, two relative humidity sensors and three VOCs leak sensors; all of them based on microstructured optical fibers. The interrogation system uses the FFT technique to isolate each sensor's interference, enabling their simultaneous interrogation. The system interrogates all the sensors at frequencies up to 1 KHz, showing a good performance of each measurement without crosstalk between sensors. The developed system is independent of the sensors' purpose or of the multiplexing topology.
Open Access
Resilient amplified double ring optical networks to multiplex optical fibre sensors
(IEEE / OSA, 2009) Fernández Vallejo, Montserrat; Pérez Herrera, Rosa Ana; Elosúa Aguado, César; Díaz Lucas, Silvia; Urquhart, Paul; Bariáin Aisa, Cándido; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
We report the experimental demonstration of two configurations of an amplified optical fibre double ring network for the multiplexing of sensors. The networks are designed to be inherently resilient to fibre failures because they enable simultaneous interrogation of all the optical fibre sensors using both rings. The first design demonstrates the feasibility of the so called 'dedicated protection' and the second one 'shared protection' for fibre optic intensity sensors. Raman amplification is used to overcome the losses of the couplers used in the rings, providing power transparency. The first network uses Raman amplification in both constituent rings but in the second one Raman pumping is activated only when a fibre failure occurs. We demonstrate how the topology allows the received powers from the sensors to be equalized.
Open Access
All-PM fiber loop mirror interferometer analysis and simultaneous measurement of temperature and mechanical vibration
(IEEE, 2018) Leandro González, Daniel; López-Amo Sáinz, Manuel; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
In this work, a new all-polarization maintaining (PM) fiber loop mirror interferometer is proposed and validated as temperature and mechanical vibration sensor. The scheme employs the arms of a PM coupler as communication fibers, fused with a relative angle of 45° to the sensing fiber. The length of the arms is equal so their contribution in canceled, obtaining a total transfer function exclusively defined by the sensing fiber. The capabilities of the system as sensor are tested, achieving mechanical vibration and temperature sensing without crosstalk between measurands. In this manner, vibration frequencies up to 1.5 kHz have been monitored using a commercial interrogator with a scan rate of 1 Hz and a technique based on the fast Fourier transform. Additionally, the immunity of the setup to external perturbations in the communication fibers is studied and compared to the conventional approach.
Open Access
Relative humidity multi-point optical sensors system based on Fast Fourier multiplexing technique
(SPIE, 2017) López Aldaba, Aitor; López Torres, Diego; Elosúa Aguado, César; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; Arregui San Martín, Francisco Javier; López-Amo Sáinz, Manuel; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
In this paper, a new multipoint optical fiber system for relative humidity measurements based on Sn02-FP (Fabry-Pérot) sensing heads and an optical interrogator as single active device is presented and characterized. The interrogation of the sensing heads is carried out by monitoring the Fast Fourier Transform phase variations of the FP (Fabry-Pérot) interference frequencies. This method allows to multiplex several sensors with different wavelength spacing interference pattern. The sensors operate within a wide humidity range (20%-90% relative humidity) with low crosstalk between them. Five sensing heads have been measured using two different channels of the optical interrogator. The availability of four channels in the interrogator allows to multiplex a higher number of sensors, reducing proportionally the cost of each sensing point.
Open Access
Simultaneous strain and temperature multipoint sensor based on microstructured optical fiber
(IEEE, 2018) López Aldaba, Aitor; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; López-Amo Sáinz, Manuel; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
In this paper, a new sensor system for simultaneous and independent multipoint strain and temperature measurements is presented. The interrogation of the sensing heads has been carried out by monitoring their FFT phase variations. In particular, two of each microstructured optical fiber (M0F) cavity interference frequencies were used for the measures. This method is independent of the signal amplitude and also avoids the necessity of tracking the wavelength evolution in the spectrum, which can be a handicap when there are multiple interference frequency components with different sensitivities. The sensing heads present birefringent and multimodal properties and therefore both characteristics lead to their own interference with different properties and sensitivities. The multiplexing capability of the sensing heads and the interrogator method has also been tested and validated. Sensors were operated within a range of temperature 30°C-80°C and a deformation of ̴450 με was applied. Crosstalk between measurements can be corrected through simple math operations leading to independent and crosstalk-free multipoint and multiparameter sensors.
Open Access
Power over fiber system for heterogeneous sensors multiplexing
(IEEE, 2024-06-12) Rodríguez Rodríguez, Armando; Vanegas Tenezaca, Evelyn Dayanara; Vento Álvarez, José Raúl; López-Amo Sáinz, Manuel; Bravo Acha, Mikel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Uniertsitate Publikoa
This paper presents a Power-over-Fiber based remote electronic and optical fiber sensors multiplexing scheme. The system architecture consists of a 50-km linear cavity Raman-fiber laser that is used for interrogation of FBG optical fiber sensors. Simultaneously, electronic sensors information is modulated in amplitude while the optical sensors' data are encoded in the spectral information. In order to bias the electronic sensors, the residual power of the Raman pump laser is collected in an energy harvesting unit. This electric power is used for biasing an ATTiny85 control unit and two electro-optical modulators. A proof-of-concept is presented where a couple of optical fiber-Bragg-gratings sensors collect strain information that is self-compensated in temperature according to the digital data achieved from the electronic sensors. A 9.6 kbit/s data rate was achieved using Mach-Zehnder amplitude modulators and a maximum 35 ksample/s was retrieved using a high-speed C-band spectrometer and performing spectral analysis via a software developed in Python. Authors