39 research outputs found
Nonlinear Dynamics and Fiber Optics Group at Instituto de Óptica “Daza de Valdes del CSIC: Experimental research lines
No full text11 pags., 10 figs. -- Ejemplar dedicado a: Óptica no lineaSe presenta y describen las líneas de trabajo experimentales que se vienen cultivando en el Grupo de
investigación en Dinámica no Lineal y Fibras ópticas, recientemente creado en el Instituto de Óptica
del CSIC.We present the experimental lines developed in last years in the Nonlinear Dynamics and Fiber
Optics Group (NDFO) of the Optics Institute “Daza de Valdés” (IO-CSIC).Agradecemos la ayuda al Ministerio de Ciencia y
Tecnología a través de los proyectos TEC2009-
14423-C02-01, TEC2009-14423-C02-02 y
TEC2008-5791, al Ministerio de Fomento a
través del proyecto MIFFO (FOM-07/77) y de la
Comunidad de Madrid a través del proyecto
FACTOTEM2 (S2009/ESP-1781). S. MartinLópez y J. Nuño agradecen al Ministerio de Ciencia y Tecnología por su contrato “Juan de la
Cierva” y beca FPI, respectivamente. Xabier
Angulo-Vinuesa agradece el apoyo económico de
ICYF S.A.Peer reviewe
Ultra-long range Brillouin Optical Time Domain Analysis
No full textNuestro estilo de vida actual, basado en la industrialización y el consumo, requiere de grandes infraestructuras que puedan dar servicio a todas las necesidades asociadas al entorno: autopistas, líneas ferroviarias de alta velocidad, presas, gasoductos, oleoductos, estaciones de aerogeneración, líneas de alta tensión, etc. Evidentemente, la seguridad de las citadas estructuras es una prioridad ya que decenas, cientos, e incluso miles de vidas pueden estar en riesgo en caso de accidente. Ese creciente requisito en términos de seguridad, está aumentando de manera considerable el desarrollo y aplicación de sensores de fibra óptica en detrimento de los típicos sensores eléctricos. Este reemplazo se debe a ciertas ventajas que tienen los dispositivos basado en fibra óptica: pequeño tamaño y ligereza, menor coste, baja atenuación, capacidad de multiplexación, inmunidad al ruido electromagnético o resistencia a temperaturas extremas. Evidentemente, no todos los sensores de fibra óptica son aplicables a cualquier tipo de estructura o aplicación. En el campo de las grandes infraestructuras (> 25-30 km), los sistemas de fibra basados en la tecnología BOTDA (Brillouin Optical Time Domain Analysis) están tomando cada vez mayor protagonismo debido a sus cualidades en rango de medida (> 50 km) y resolución (< 10 m). Este tipo de sensores, denominados distribuidos por su capacidad de "convertir" cada sección de fibra en un sensor simplemente introduciendo luz por ambos extremos de la propia fibra, proporcionan información de variaciones de temperatura y deformación, y por consiguiente de cualquier magnitud asociada a ambas. La necesidad de introducir dos señales de luz en la fibra objetivo dificulta la aplicación de este tipo de sistemas en ciertas infraestructuras de muy larga distancia (> 100 km), donde la fibra tenga que ir y volver a la estación de sensado (> 200 km) sin posibilidad de que la luz sea amplificada por algún elemento intermedio. Además, cada vez se demanda más la posibilidad de monitorizar grandes estructuras (> 100 km) con resoluciones por debajo del metro, lo que dificulta considerablemente la implementación de los sistemas BOTDA. En este trabajo de tesis, se desarrolla un estudio cuidadoso de todos los problemas asociados al incremento de distancia y resolución en sistemas BOTDA y, consecuentemente, se proponen técnicas aplicables para evitarlos. En particular, abordaremos en profundidad los desafíos y las constantes de diseño de los sistemas BOTDA asistidos por Raman. La amplificación Raman en sistemas BOTDA implica un aumento del rango de sensado pero, desgraciadamente, introduce un ruido en la señal detectada denominado RIN (Relative Intensity Noise). Para evitar los problemas asociados a la transferencia de RIN, propondremos diferentes métodos capaces de eliminar parcialmente las características típicas del ruido RIN. Gracias a la aplicación de estas nuevas técnicas y procedimientos de optimización, se demuestra de manera experimental el sensado a lo largo de 100 km con 0,5 metros de resolución y, por primera vez, una medición lineal de 240 km de fibra (120 km de fibra sensible) con una resolución de 5 metros
Kerr effect in structured superluminal media
No full textA comprehensive overview is presented about optical fiber-based tunable photonic delay lines, which have been steadily developed over the last decade for the realization of all-optically controlled timing functions. The most widely used techniques, such as those based on slow & fast light and wavelength conversion associated to dispersion, are described and their physical limitations are discussed in terms of the maximal achievable delay, the associated signal distortion and signal bandwidth. Besides, an entirely different approach for all-optical signal delaying is introduced. This technique is based on movable grating reflectors dynamically generated in highly birefringent optical fibers. This type of delay line has experimentally demonstrated large tunable delaying with a moderate signal distortion for high capacity optical data streams and even for wideband analog signals.THEVESCI-STI-LTInvited pape
Raman-assisted Brillouin distributed temperature sensor over 100 km featuring 2 m resolution and 1.2 °c uncertainty
No full textRaman assistance in distributed sensors based on Brillouin optical time-domain analysis can significantly extend the measurement distance. In this paper, we have developed a 2 m resolution long-range Brillouin distributed sensor that reaches 100 km using first-order Raman assistance. The estimated uncertainty in temperature discrimination is 1.2 °C, even for the position of worst contrast. The parameters used in the experiment are supported by a simple analytical model of the required values, considering the main limitations of the setup. © 2012 IEEE.This work was supported in part by the Spanish
Ministry of Science and Innovation through Project TEC2009-14423-C02-01
and Project TEC2009-14423-C02-02, the Ministerio de Fomento through
projects MIFFO (FOM-07/77) and IFZONE (FOM 39/08), and the Comunidad
de Madrid through project FACTOTEM2.Peer Reviewe
Raman-assisted Brillouin optical time-domain analysis with sub-meter resolution over 100 km
No full textSub-meter resolution in long-distance Brillouin Optical Time Domain Analysis (BOTDA) cannot be trivially achieved due to several issues including: resolution-uncertainty trade-offs, self-phase modulation, fiber attenuation, depletion, etc. In this paper we show that combining Raman assistance, differential pulse-width pair (DPP) measurements and a novel numerical de-noising procedure, we could obtain sub-meter resolution Brillouin optical time-domain analysis over a range of 100 km. We successfully demonstrate the detection of a 0.5 meter hot-spot in the position of worst contrast along the fiber. © 2012 Optical Society of America.This work was supported in part by the Spanish Ministry of Science and Innovation through projects TEC2009-14423-C02-01 and TEC2009-14423-C02-02 and the Comunidad de Madrid through project FACTOTEM-2. Sonia Martin-Lopez acknowledges funding from the Spanish Ministry of Science and Innovation through a “Juan de la Cierva” contract.Peer Reviewe
100km BOTDA temperature sensor with sub-meter resolution
No full text22nd International Conference on Optical Fiber Sensors (OFS2012), Beijing, China | October 14, 2012Temperature or strain sensing in long-range (> 70 km) Brillouin Optical Time Domain Analysis (BOTDA) below 2 meter resolution cannot be trivially achieved due to numerous matters such as fiber attenuation, self-phase modulation, depletion, resolution-uncertainty trade-offs, etc. In this paper we show that combining Raman assistance and the Differential Pulse-width Pair (DPP) technique sub-metrical resolution is achievable in a BOTDA over 100 km sensing range. We successfully demonstrate the detection of a 0.5 meter hot-spot in the position of worst contrast along the fiber.Ministerio de Ciencia e InnovaciónComunidad de Madri
Wide range group delay tuning in lossy fiber ring resonators
No full text22nd International Conference on Optical Fiber Sensors, OFS 2012, Beijing, China, 15-19 Oct. 2012We demonstrate theoretically and experimentally that a wide-range tuning of group delay values can be achieved in a\ud
lossy fiber ring resonator. The tuning mechanism relies simply on varying the loss/coupling ratio in the resonator. This\ud
simple structure may be used advantageously in different regimes for many sensing configurations, both for achieving\ud
extremely high sensitivity enhancements (by working close to critical coupling, where the group index becomes\ud
extremely large) or suppression of undesired refractive index effects (e.g. Kerr effect), by working in the under-coupled\ud
regime
Versatile all-fiber slow-light assisted sensor
No full textWe present theoretical and experimental results on a slow-light assisted all-fiber configuration that can be used for\ud
efficient sensing of a variety of parameters (pressure, displacement...). In particular, we report here a structure that can be\ud
transformed into a slow-light assisted displacement sensor capable of sub-micrometric resolution values with a\ud
potentially simple intensiometric measurement scheme. The basic element in the structure is a lossy ring resonator tuned\ud
close to the critical coupling regime. In this working regime, the resonator transfer function displays extremely high\ud
group delay values close to the resonances, and, accordingly, a large sensitivity to additional losses. A mechanic\ud
transducer transforms displacement into small additional losses in the ring. This leads to strong variations in the log\ud
transmission of the resonances, which are shown to scale with the group index. This scheme shows orders of magnitude\ud
sensitivity enhancements over a conventional bending-loss configuration. We believe that this structure can be further\ud
developed to provide large sensitivity enhancements to conventional intensiometric fiber sensors
High-resolution Raman-assisted Brillouin sensor based on Differential Pulse-width Pair Technique
No full textHigh sensing resolution in long-distance distributed fiber optic sensors, such as Brillouin Optical Time Domain Analysis\ud
(BOTDA), cannot be trivially achieved due to several issues including self-phase modulation, resolution-uncertainty\ud
trade-offs and fiber attenuation. These problems could be fixed by the use of differential pulse-pair techniques in\ud
combination with Raman amplification. In this work we present a Differential Pulse-width Pair (DPP) Raman-assisted\ud
BOTDA sensor, that can achieve 1 meter resolution in a 100 km range
Turning a low Q fiber resonator into a high-sensitivity displacement sensor using slow light concepts
No full textHigh-Q resonators have been widely used for sensing purposes. High Q factors normally lead to sharp spectral peaks which accordingly provide a strong sensitivity in spectral interrogation methods. In this work we employ a low-Q ring resonator to develop a high sensitivity sub-micrometric resolution displacement sensor. We use the slow-light effects occurring close to the critical coupling regime to achieve high sensitivity in the device. By tuning the losses in the cavity close to the critical coupling, extremely high group delay variations can be achieved, which in turn introduce strong enhancements of the absorption of the structure. We first validate the concept using an Optical Vector Analyzer (OVA) and then we propose a simple functional scheme for achieving a low-cost interrogation of this kind of sensors.European CommissionMinisterio de Ciencia e InnovaciónComunidad de MadridMinisterio de Economía y Competitivida
