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Sample records for bragg grating sensors

  1. Fiber Bragg grating sensors

    NARCIS (Netherlands)

    Cheng, L.K.; Nieuwland, R.A.; Toet, P.M.; Agovic, K.

    2010-01-01

    A brief overview of fiber Bragg grating based sensor technology from sensor head, read out unit and commercial applications is given. Fiber Bragg grating based sensor systems are becoming mature rapidly. Components for commercial pressure sensors and temperature sensors are available and slowly gett

  2. MEMS Bragg grating force sensor

    DEFF Research Database (Denmark)

    Reck, Kasper; Thomsen, Erik Vilain; Hansen, Ole

    2011-01-01

    We present modeling, design, fabrication and characterization of a new type of all-optical frequency modulated MEMS force sensor based on a mechanically amplified double clamped waveguide beam structure with integrated Bragg grating. The sensor is ideally suited for force measurements in harsh...... environments and for remote and distributed sensing and has a measured sensitivity of -14 nm/N, which is several times higher than what is obtained in conventional fiber Bragg grating force sensors. © 2011 Optical Society of America....

  3. Characteristics of Smart Concrete with Fiber Optical Bragg Grating Sensor

    Institute of Scientific and Technical Information of China (English)

    XIN Si-jin; JIANG De-sheng; LIANG Lei; Luo Pei; ZUO Jun; NAN Qiu-ming; CHEN Da-xiong

    2004-01-01

    Based on the advantages of the fiber Bragg grating sensing technology, this paper presents a principle of a novel smart concrete with fiber optical Bragg grating sensor, analyses the theory and characteristics,illustrates the key technology and method to make the fiber Bragg grating sensor for the smart concrete, and proves the feasibility with experiments. The results indicate that the smart concrete with fiber Bragg grating sensors is feasible in the structure monitoring and damage diagnosing in the long run.

  4. Fiber Bragg Grating Filter High Temperature Sensors

    Science.gov (United States)

    Lyons, Donald R.; Brass, Eric D.; Pencil, Eric (Technical Monitor)

    2001-01-01

    We present a scaled-down method for determining high temperatures using fiber-based Bragg gratings. Bragg gratings are distributed along the length of the optical fiber, and have high reflectivities whenever the optical wavelength is twice the grating spacing. These spatially distinct Bragg regions (located in the core of a fiber) are sensitive to local temperature changes. Since these fibers are silica-based they are easily affected by localized changes in temperature, which results in changes to both the grating spacing and the wavelength reflectivity. We exploit the shift in wavelength reflectivity to measure the change in the local temperature. Note that the Bragg region (sensing area) is some distance away from where the temperature is being measured. This is done so that we can measure temperatures that are much higher than the damage threshold of the fiber. We do this by affixing the fiber with the Bragg sensor to a material with a well-known coefficient of thermal expansion, and model the heat gradient from the region of interest to the actual sensor. The research described in this paper will culminate in a working device as well as be the second portion of a publication pending submission to Optics Letters.

  5. Polymer optical fiber bragg grating sensors

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, Scott Wu; Andresen, Søren;

    2010-01-01

    Fiber-optical accelerometers based on polymer optical fiber Bragg gratings are reported. We have written fiber Bragg gratings for 1550 nm and 850 nm operations, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

  6. Fiber Bragg Grating Sensors for Harsh Environments

    Directory of Open Access Journals (Sweden)

    Stephen J. Mihailov

    2012-02-01

    Full Text Available Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This paper will present a review of some of the more recent developments.

  7. Composite cure monitoring with Bragg grating sensors

    Science.gov (United States)

    Slattery, Kerry T.; Corona-Bittick, Kelli; Dorr, Donald J.

    1998-03-01

    Residual stress is induced in fiber composite materials during the cure process because the thermal expansion coefficient of the fiber is generally much lower than that of the polymer matrix. The two materials are 'locked' together at the cure temperature. Then, as they cool, the matrix attempts to contract more than the fiber leading to tension in the matrix and compression in the fiber. This can lead to the formation of microcracks parallel to the fibers in thick composite piles or yarns. The magnitude of residual stress can be reduced by modifying the cure cycle; however, optimizing the cure cycle requires a complete understanding of the state of cure throughout the composite. This is a complex problem -- especially in thick composites. Pilot studies have been performed placing Bragg gratin sensors in glass fabric preforms and monitoring the response of the grating during resin infusion and cure. The typical response shows the initial thermal expansion of the Bragg grating, a rapid contraction of the grating as the resin gels, slower contraction during cure, and thermal contraction at the composite thermal expansion coefficient during cool down. This data is then sued with micromechanical models of the fiber/matrix interaction during cure to establish material parameters for cure simulation. Once verified, these cure simulation methods will be used to optimize tooling design and cure cycles in composite components.

  8. Time/Wavelength Fiber Bragg Grating Multiplexing Sensor Array

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel time/wavelength-multiplexed fiber Bragg grating sensor array is presented. This type of sensor array has the advantages of more points for multi-point measurement, simple structure and low cost.

  9. Multipoint sensor based on fiber Bragg gratings

    Energy Technology Data Exchange (ETDEWEB)

    Mendez-Zepeda, O; Munoz-Aguirre, S; Beltran-Perez, G; Castillo-Mixcoatl, J, E-mail: mezeos9@yahoo.com [Facultad de Ciencias FIsico-Matematicas, BUAP Av. San Claudio y Rio Verde, Col. San Manuel, CU. C.P. 72570, Puebla, Puebla (Mexico)

    2011-01-01

    In some control and industrial measurement systems of physical variables (pressure, temperature, flow, etc) it is necessary one system and one sensor to control each process. On the other hand, there are systems such as PLC (Programmable Logic Control), which can process several signals simultaneously. However it is still necessary to use one sensor for each variable. Therefore, in the present work the use of a multipoint sensor to solve such problem has been proposed. The sensor consists of an optical fiber laser with two Fabry-Perot cavities constructed using fiber Bragg gratings (FBG). In the same system is possible to measure changes in two variables by detecting the intermodal separation frequency of each cavity and evaluate their amplitudes. The intermodal separation frequency depends on each cavity length. The sensor signals are monitored through an oscilloscope or a PCI card and after that acquired by PC, where they are analyzed and displayed. Results of the evaluation of the intermodal frequency separation peak amplitude behavior with FBG stretching are presented.

  10. Bragg grating chemical sensor with hydrogel as sensitive element

    Institute of Scientific and Technical Information of China (English)

    Xiaomei Liu(刘小梅); Shilie Zheng(郑史烈); Xianmin Zhang(章献民); Jun Cong(丛军); Kangsheng Chen(陈抗生); Jian Xu(徐坚)

    2004-01-01

    A novel fiber Bragg grating (FBG) based chemical sensor using hydrogel, a swellable polymer, as sensitive element is demonstrated. The sensing mechanism relies on the shift of Bragg wavelength due to the stress resulted from volume change of sensitive swellable hydrogel responding to the change of external environment. A polyacrylamide hydrogel fiber grating chemical sensor is made, and the experiments on its sensitivity to the salinity are performed. The sensitivity is low due to the less stress from the shrinking or swelling of hydrogels. Reducing the cross diameter of the grating through etching with hydrofluoric acid can greatly improve the sensitivity of the sensor.

  11. Damage behaviors of fiber Bragg grating sensor in fabrication

    Science.gov (United States)

    Tang, Liqun; Sang, Dengfeng; Chen, Jinming; Yang, Bao; Liu, Yiping

    2008-11-01

    It is has been noted that for fiber Bragg grating sensor (FBGS), the tensile strengths of fiber Bragg grating sensors (FBGSs) were decreased after the gratings were written, which may reduce the sensor's measurement range obviously. In this paper, we focused on the damage behaviours of FBGS after fabrication experimentally. Firstly, the tensile tests were carried to measure the tensile strengths of naked optical fiber, decoated optical fiber and optical fiber with Bragg gratings to learn deduction of the tensile strength of optical fiber in the cases respectively. Further, the microscope photography was used to observe the surfaces of optical fiber with or without exposure of excimer laser. The main conclusion is that the UV pulse is the main contribution to reduce the strength remarkably, and the mechanical decoating method also can induce the surface damage on the optical fiber.

  12. Technical textiles with embedded fibre Bragg grating sensors

    Science.gov (United States)

    Bilro, L.; Cunha, H.; Pinto, J. L.; Nogueira, R. N.

    2009-10-01

    The characterization of fiber Bragg grating (FBG) sensors integrated on 2D and 3D mesh structures is presented. Several materials and configurations were tested, namely cork, foams, PVC, hexagonal 3D. Sensors were embedded between two substrates using textile lamination technique. Every sample was subjected to temperature variations and mechanical deformations. Through Bragg wavelength monitoring, thermal, deformation and pressure performance were evaluated. These results provide significant information to the conception of smart textiles.

  13. Applications of distributed fiber Bragg grating sensors in civil engineering

    Science.gov (United States)

    Nellen, Philipp M.; Broennimann, Rolf; Sennhauser, Urs J.; Askins, Charles G.; Putnam, Martin A.

    1995-09-01

    We report on civil engineering applications of wavelength multiplexed optical-fiber Bragg grating arrays produced directly on the draw tower for testing and surveying advanced structures and material like carbon fiber reinforced concrete elements and prestressing tendons. We equipped a 6 m X 0.9 m X 0.5 m concrete cantilever beam reinforced with carbon fiber lamellas with fiber Bragg grating sensors. Static and dynamic strain levels up to 1500 micrometers /m were measured with a Michelson interferometer used as Fourier spectrometer with resolutions of about 10 micrometers /m for all sensors. Comparative measurements with electrical resistance strain gauges were in good agreement with the fiber optic results. We used the fiber sensors in two different arrangements: some Bragg grating array elements measured the local strain while others were configured in an extensometric way to measure moderate strain over 0.1-1 m.

  14. Monolithic integrated optic fiber Bragg grating sensor interrogator

    Science.gov (United States)

    Mendoza, Edgar A.; Esterkin, Yan; Kempen, Cornelia; Sun, Songjian

    2010-04-01

    Fiber Bragg gratings (FBGs) are a mature sensing technology that has gained rapid acceptance in civil, aerospace, chemical and petrochemical, medicine, aviation and automotive industries. Fiber Bragg grating sensors can be use for a variety of measurements including strain, stress, vibration, acoustics, acceleration, pressure, temperature, moisture, and corrosion distributed at multiple locations within the structure using a single fiber element. The most prominent advantages of FBGs are: small size and light weight, multiple FBG transducers on a single fiber, and immunity to radio frequency interference. A major disadvantage of FBG technology is that conventional state-of-the-art fiber Bragg grating interrogation systems are typically bulky, heavy, and costly bench top instruments that are assembled from off-the-shelf fiber optic and optical components integrated with a signal electronics board into an instrument console. Based on the need for a compact FBG interrogation system, this paper describes recent progress towards the development of a miniature fiber Bragg grating sensor interrogator (FBG-TransceiverTM) system based on multi-channel monolithic integrated optic sensor microchip technology. The integrated optic microchip technology enables the monolithic integration of all of the functionalities, both passive and active, of conventional bench top FBG sensor interrogators systems, packaged in a miniaturized, low power operation, 2-cm x 5-cm small form factor (SFF) package suitable for the long-term structural health monitoring in applications where size, weight, and power are critical for operation.

  15. Temperature sensor based on dual fiber Bragg gratings

    OpenAIRE

    Ekestam, Henrik; Larsson, Jim

    2015-01-01

    The objective of the project was to examine if it was possible to develop a low-cost temperature sensor using dual fiber Bragg gratings (FBGs). The intention was to use one FBG as a reference and let the other FBG function as the sensor. The study shows that it is possible to characterize the temperature sensitivity of each FBG and use the reference to sweep over the applicable spectrum to find the Bragg-wavelength of the sensor. This could be done measuring only the total intensity instead o...

  16. Temperature Compensation for Double Fiber Bragg Grating Sensors

    Institute of Scientific and Technical Information of China (English)

    WANG Chun-cheng; LIU Jia; ZHENG Jian-bang

    2006-01-01

    A novel double fiber Bragg grating(FBG) strain sensor configuration is presented. Temperature compensation method is based on double FBG moored on a rhombus frame. Through the theoretical analysis,the relation between relative shift of Bragg wavelength and the strain applied on the sensor is obtained,and the analytical expression of strain sensitivity coefficient is also given. The experiment results show that:in the strain range of 0~0.8 mm,the relation between the relative shift of Bragg wavelength and applied strain is linear,and the dispersion of double FBG wavelength at the range of -25 ℃~60 ℃ is 0~0.002 nm. The strain sensitivity of the displacement sensor configuration is 0.171 nm/με,and is nearly twice than that of single FC sensor.

  17. Fiber Bragg Grating Pressure Sensor Based on Corrugated Diaphragm

    Institute of Scientific and Technical Information of China (English)

    FU Hai-wei; FU Jun-mei; QIAO Xue-guang

    2004-01-01

    A kind of fiber Bragg grating pressure sensor based on corrugated diaphragm is proposed. The relationship between the central wavelength of reflective wave of FBG and pressure is given, and the expression of the pressure sensitivity coefficient is also given. Within the range from results agree with the theoretical analysis. It is indicated that the expected pressure sensitivity of the sensor can be obtained by optimizing the size and mechanical parameters of the corrugated diaphragm.

  18. High sensitivity fiber Bragg grating pressure difference sensor

    Institute of Scientific and Technical Information of China (English)

    Haiwei Fu(傅海威); Junmei Fu(傅君眉); Xueguang Qiao(乔学光)

    2004-01-01

    Based on the effect of fiber Bragg grating (FBG) pressure difference sensitivity enhancement by encapsulating the FBG with uniform strength beam and metal bellows, a FBG pressure difference sensor is proposed, and its mechanism is also discussed. The relationship between Bragg wavelength and the pressure difference is derived, and the expression of the pressure difference sensitivity coefficient is also given. It is indicated that there is good linear relation between the Bragg wavelength shift and the pressure difference of the sensor. The theoretical and experimental pressure difference sensitivity coefficients are 38.67 and 37.6 nm/MPa, which are 12890 and 12533 times of that of the bare FBG, respectively. The pressure difference sensitivity and dynamic range can be easily changed by changing the size, Young's modulus, and Poisson's ratio of the beam and the bellows.

  19. DESIGN AND SIMULATION OF FIBER BRAGG GRATING BASED SENSORS

    OpenAIRE

    MOHAMED M. SALEH; RIADH K. A. Al-ANI; ILHAM K. ONEES

    2014-01-01

    In this paper the temperature and strain sensing principle of FBG based sensors are design & simulated by using Optigrating software. Simulation tools provide valuable help in optimizing the design parameters.From the graphical simulations, it can be concluded that there is a linear relationship between the Bragg wavelength shift and the temperature as well as the strain change. Also different values of grating period due to increasing the value of shifted wavelength.

  20. Trial analysis of swine's periodontal ligament with Bragg grating sensors

    Science.gov (United States)

    Menegotto, G. F.; Grabarski, L.; Kalinowski, H. J.; Simões, J. A.

    2009-10-01

    In this work it is reported the measurement of the differential strain between the dental and bone tissues under effect of an applied load. Slices of swine mandible, containing the premolar tooth, are cut and measured in fresh condition. The strain is measured using fibre Bragg grating sensors glued to both tissues. In the measured range the results show a linear behaviour and confirm the importance of the periodontal ligament in the load transfer mechanism.

  1. A high sensitive fiber Bragg grating cryogenic temperature sensor

    Institute of Scientific and Technical Information of China (English)

    Kuo Li; Zhen'an Zhou; Aichun Liu

    2009-01-01

    At cryogenic temperature, a fiber Bragg grating (FBG) temperature sensor with controllable sensitivity and variable measurement range is demonstrated by using bimetal configuration. In experiments, sensitivities of -51.2, -86.4, and -520 pm/K are achieved by varying the lengths of the metals. Measurement ranges of 293 - 290.5, 283 - 280.5, and 259 - 256.5 K are achieved by shortening the distance of the gap among the metals.

  2. Fiber Bragg grating pressure sensor with enhanced sensitivity

    Institute of Scientific and Technical Information of China (English)

    Wentao Zhang; Lihui Liu; Fang Li; Yuliang Liu

    2007-01-01

    @@ A novel fiber Bragg grating (FBG) pressure sensor with the enhanced sensitivity has been demonstrated. A piston-like diaphragm with a hard core in the center is used to enhance the sensitivity. Both the theoretical analysis and the experimental result show that the radius of the hard core has significant effect on the pressure sensitivity. When the radius of the hard core is 1.5 mm, a pressure sensitivity of 7.23 nm/MPa has been achieved.

  3. Laser sensor with Bragg gratings of fiber optics to physics parameter measuring

    International Nuclear Information System (INIS)

    We present the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980nm, an 4.23 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength increases their temperature which can be used as a sensor element. The laser generation thus shows that the Bragg grating is increasing their temperature. We used a Peltier cell for to change gradually the temperature. (Author)

  4. Structural Health Monitoring of Bridges with Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Francisco Navarro-Henríquez

    2014-11-01

    Systems with fiber optic sensors FBG (Fiber Bragg Grating are consolidated in the Structural Health Monitoring (SMH of bridges, Nondestructive Testing (NDT static and dynamic measurements of deformation, displacement, deflection, temperature and vibration. This article provides a brief introduction to the technology and the fundamentals of fiber optic sensors, also present comparative advantages over its traditional counterpart is presented. Their characteristics are described and measurement graphics are presented as an application example of the FBG sensors. Finally, some key aspects to consider for proper use in the field are mentioned.

  5. A fast response temperature sensor based on fiber Bragg grating

    International Nuclear Information System (INIS)

    Aimed at the requirement for a fast-response expendable ocean temperature sensor, this paper presents a new design scheme for an optic fiber sensor. Ocean temperature sensors require high sensitivity and high response speed, which must be up to milliseconds. The fiber Bragg grating (FBG) temperature sensor with high sensitivity has been declared in the last decade, but its response speed has been rarely reported. In this paper, a method is proposed which is to package an FBG with a metal tube. The response time of this sensor is 48.6 ms, which is an order of magnitude greater than that of an ordinary optical fiber temperature sensor. Temperature sensitivity is 27.6 pm/°C and the linearity is up to 0.9999. In addition, the sensor can be less than 15 mm. It offers a new way to detect ocean temperature. (paper)

  6. On-Chip Silicon Waveguide Bragg Grating Photonic Temperature Sensor

    CERN Document Server

    Klimov, Nikolai N; Berger, Michaela; Ahmed, Zeeshan

    2015-01-01

    Resistance thermometry is a time-tested method for taking temperature measurements. In recent years fundamental limits to resistance-based approaches spurred considerable interest in developing photonic temperature sensors as a viable alternative. In this study we demonstrate that our photonic thermometer, which consists of a silicon waveguide integrated with a Bragg grating, can be used to measure temperature changes over the range from 5 C to 160 C with a combined expanded uncertainty [k = 2 ; 95% confidence level] of 1.25 degree C. The computational modeling of the sensor predicts the resonance wavelength and effective refractive index within 4% of the measured value.

  7. Fiber Bragg Grating (FBG) sensors as flatness and mechanical stretching sensors

    Science.gov (United States)

    Abbaneo, D.; Abbas, M.; Abbrescia, M.; Abdelalim, A. A.; Abi Akl, M.; Aboamer, O.; Acosta, D.; Ahmad, A.; Ahmed, W.; Ahmed, W.; Aleksandrov, A.; Aly, R.; Altieri, P.; Asawatangtrakuldee, C.; Aspell, P.; Assran, Y.; Awan, I.; Bally, S.; Ban, Y.; Banerjee, S.; Barashko, V.; Barria, P.; Bencze, G.; Beni, N.; Benussi, L.; Bhopatkar, V.; Bianco, S.; Bos, J.; Bouhali, O.; Braghieri, A.; Braibant, S.; Buontempo, S.; Calabria, C.; Caponero, M.; Caputo, C.; Cassese, F.; Castaneda, A.; Cauwenbergh, S.; Cavallo, F. R.; Celik, A.; Choi, M.; Choi, S.; Christiansen, J.; Cimmino, A.; Colafranceschi, S.; Colaleo, A.; Conde Garcia, A.; Czellar, S.; Dabrowski, M. M.; De Lentdecker, G.; De Oliveira, R.; De Robertis, G.; Dildick, S.; Dorney, B.; Elmetenawee, W.; Endroczi, G.; Errico, F.; Fenyvesi, A.; Ferry, S.; Furic, I.; Giacomelli, P.; Gilmore, J.; Golovtsov, V.; Guiducci, L.; Guilloux, F.; Gutierrez, A.; Hadjiiska, R. M.; Hassan, A.; Hauser, J.; Hoepfner, K.; Hohlmann, M.; Hoorani, H.; Iaydjiev, P.; Jeng, Y. G.; Kamon, T.; Karchin, P.; Korytov, A.; Krutelyov, S.; Kumar, A.; Kim, H.; Lee, J.; Lenzi, T.; Litov, L.; Loddo, F.; Madorsky, A.; Maerschalk, T.; Maggi, M.; Magnani, A.; Mal, P. K.; Mandal, K.; Marchioro, A.; Marinov, A.; Masod, R.; Majumdar, N.; Merlin, J. A.; Mitselmakher, G.; Mohanty, A. K.; Mohamed, S.; Mohapatra, A.; Molnar, J.; Muhammad, S.; Mukhopadhyay, S.; Naimuddin, M.; Nuzzo, S.; Oliveri, E.; Pant, L. M.; Paolucci, P.; Park, I.; Passeggio, G.; Passamonti, L.; Pavlov, B.; Philipps, B.; Piccolo, D.; Pierluigi, D.; Postema, H.; Puig Baranac, A.; Radi, A.; Radogna, R.; Raffone, G.; Ranieri, A.; Rashevski, G.; Riccardi, C.; Rodozov, M.; Rodrigues, A.; Ropelewski, L.; RoyChowdhury, S.; Russo, A.; Ryu, G.; Ryu, M. S.; Safonov, A.; Salva, S.; Saviano, G.; Sharma, A.; Sharma, A.; Sharma, R.; Shah, A. H.; Shopova, M.; Sturdy, J.; Sultanov, G.; Swain, S. K.; Szillasi, Z.; Talvitie, J.; Tatarinov, A.; Tuuva, T.; Tytgat, M.; Vai, I.; Van Stenis, M.; Venditti, R.; Verhagen, E.; Verwilligen, P.; Vitulo, P.; Volkov, S.; Vorobyev, A.; Wang, D.; Wang, M.; Yang, U.; Yang, Y.; Yonamine, R.; Zaganidis, N.; Zenoni, F.; Zhang, A.

    2016-07-01

    A novel approach which uses Fiber Bragg Grating (FBG) sensors has been utilized to assess and monitor the flatness of Gaseous Electron Multipliers (GEM) foils. The setup layout and preliminary results are presented.

  8. Fiber Bragg Grating (FBG) sensors as flatness and mechanical stretching sensors

    CERN Document Server

    Abbaneo, D; Abbrescia, M.; Abdelalim, A.A.; Abi Akl, M.; Aboamer, O.; Acosta, D.; Ahmad, A.; Ahmed, W.; Ahmed, W.; Aleksandrov, A.; Aly, R.; Altieri, P.; Asawatangtrakuldee, C.; Aspell, P.; Assran, Y.; Awan, I.; Bally, S.; Ban, Y.; Banerjee, S.; Barashko, V.; Barria, P.; Bencze, G.; Beni, N.; Benussi, L.; Bhopatkar, V.; Bianco, S.; Bos, J.; Bouhali, O.; Braghieri, A.; Braibant, S.; Buontempo, S.; Calabria, C.; Caponero, M.; Caputo, C.; Cassese, F.; Castaneda, A.; Cauwenbergh, S.; Cavallo, F.R.; Celik, A.; Choi, M.; Choi, S.; Christiansen, J.; Cimmino, A.; Colafranceschi, S.; Colaleo, A.; Conde Garcia, A.; Czellar, S.; Dabrowski, M.M.; De Lentdecker, G.; De Oliveira, R.; De Robertis, G.; Dildick, S.; Dorney, B.; Elmetenawee, W.; Endroczi, G.; Errico, F.; Fenyvesi, A.; Ferry, S.; Furic, I.; Giacomelli, P.; Gilmore, J.; Golovtsov, V.; Guiducci, L.; Guilloux, F.; Gutierrez, A.; Hadjiiska, R.M.; Hassan, A.; Hauser, J.; Hoepfner, K.; Hohlmann, M.; Hoorani, H.; Iaydjiev, P.; Jeng, Y.G.; Kamon, T.; Karchin, P.; Korytov, A.; Krutelyov, S.; Kumar, A.; Kim, H.; Lee, J.; Lenzi, T.; Litov, L.; Loddo, F.; Madorsky, A.; Maerschalk, T.; Maggi, M.; Magnani, A.; Mal, P.K.; Mandal, K.; Marchioro, A.; Marinov, A.; Masod, R.; Majumdar, N.; Merlin, J.A.; Mitselmakher, G.; Mohanty, A.K.; Mohamed, S.; Mohapatra, A.; Molnar, J.; Muhammad, S.; Mukhopadhyay, S.; Naimuddin, M.; Nuzzo, S.; Oliveri, E.; Pant, L.M.; Paolucci, P.; Park, I.; Passeggio, G.; Passamonti, L.; Pavlov, B.; Philipps, B.; Piccolo, D.; Pierluigi, D.; Postema, H.; Puig Baranac, A.; Radi, A.; Radogna, R.; Raffone, G.; Ranieri, A.; Rashevski, G.; Riccardi, C.; Rodozov, M.; Rodrigues, A.; Ropelewski, L.; RoyChowdhury, S.; Russo, A.; Ryu, G.; Ryu, M.S.; Safonov, A.; Salva, S.; Saviano, G.; Sharma, A.; Sharma, A.; Sharma, R.; Shah, A.H.; Shopova, M.; Sturdy, J.; Sultanov, G.; Swain, S.K.; Szillasi, Z.; Talvitie, J.; Tatarinov, A.; Tuuva, T.; Tytgat, M.; Vai, I.; Van Stenis, M.; Venditti, R.; Verhagen, E.; Verwilligen, P.; Vitulo, P.; Volkov, S.; Vorobyev, A.; Wang, D.; Wang, M.; Yang, U.; Yang, Y.; Yonamine, R.; Zaganidis, N.; Zenoni, F.; Zhang, A.

    2016-01-01

    A novel approach which uses Fibre Bragg Grating (FBG) sensors has been utilised to assess and monitor the flatness of Gaseous Electron Multipliers (GEM) foils. The setup layout and preliminary results are presented.

  9. Fiber Bragg grating sensors: a market overview

    Science.gov (United States)

    Méndez, A.

    2007-07-01

    Over the last few years, optical fiber sensors have seen increased acceptance and widespread use. Among the multitude of sensor types, FBG based sensors, more than any other particular sensor type, have become widely known and popular. Given their intrinsic capability to measure a multitude of parameters such as strain, temperature, pressure, chemical and biological agents - and many others - coupled with their flexibility of design to be used as single point or multi-point sensing arrays and their relative low cost, make of FBGs ideal devices to be adopted for a multitude of different sensing applications and implemented in different fields and industries. However, some technical hurdles and market barriers need to be overcome in order for this technology - and fiber sensors in general - to gain more commercial momentum and achieve faster market growth such as the need for industry standards on FBGs and FBG-based sensors, adequate packaging designs, as well as training and education of prospective customers and end-users.

  10. Muscular condition monitoring system using fiber bragg grating sensors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Heon Young; Lee, Jin Hyuk; Kim, Dae Hyun [Seoul National University of Technology, Seoul (Korea, Republic of)

    2014-10-15

    Fiber optic sensors (FOS) have advantages such as electromagnetic interference (EMI) immunity, corrosion resistance and multiplexing capability. For these reasons, they are widely used in various condition monitoring systems (CMS). This study investigated a muscular condition monitoring system using fiber optic sensors (FOS). Generally, sensors for monitoring the condition of the human body are based on electro-magnetic devices. However, such an electrical system has several weaknesses, including the potential for electro-magnetic interference and distortion. Fiber Bragg grating (FBG) sensors overcome these weaknesses, along with simplifying the devices and increasing user convenience. To measure the level of muscle contraction and relaxation, which indicates the muscle condition, a belt-shaped FBG sensor module that makes it possible to monitor the movement of muscles in the radial and circumferential directions was fabricated in this study. In addition, a uniaxial tensile test was carried out in order to evaluate the applicability of this FBG sensor module. Based on the experimental results, a relationship was observed between the tensile stress and Bragg wavelength of the FBG sensors, which revealed the possibility of fabricating a muscular condition monitoring system based on FBG sensors.

  11. Fiber Bragg grating (FBG) sensors used in coal mines

    Science.gov (United States)

    Wang, Jinyu; Liu, Tongyu; Song, Guangdong; Xie, Hongjing; Li, Lianqing; Deng, Xiaolin; Gong, Zhijie

    2014-06-01

    The fiber Bragg grating (FBG) strain sensors were used for on-line monitoring of the stress variation of the lined wall in the gateway retained along the goaf of No. 3203 coal mining face in Dongtan Mine. The results showed that the FBG strain sensor with the wide measuring range could measure the stress variation accurately during the support process of the gateway retained along the goaf and could provide the basis to further optimize the support structure and to determine the support plan of the gateway retained along the goaf. The FBG micro-seismic sensors were used in Xinglong Mine to detect the micro-seismic signal. The signals were well received and analyzed to determine the location and energy level of the source of the micro-seismic event warning. The FBG sensors and detecting system show a significant potential for micro-seismic detection and geological disasters detection.

  12. Optical Properties of High Sensitivity Fiber Bragg Grating on Temperature Sensor

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, the spectrum shift properties of the center reflection wavelength detected to be based on the FBG sensor with ambient temperature change. The basic theoretical methods and numerical simulation for the spectral properties of uniform Bragg grating is analyzed by using coupling mode theory which is optical properties of high sensitivity fiber Bragg grating on temperature sensor in accordance with experiment.

  13. Open pit slope deformation monitoring by fiber Bragg grating sensors

    Science.gov (United States)

    Xu, Guoquan; Xiong, Daiyu; Duan, Yun; Cao, Xiaoshuang

    2015-01-01

    With microstrain resolution and the capability to sample at rates of 2000 Hz or higher, fiber Bragg grating (FBG) strain sensor offers exciting new possibilities for in situ deformation monitoring induced by blasting load in an open pit slope. Here, we are developing a new technology for measuring deformation in real time on the microstrain in an open pit slope during the blasting. A fiber optically instrumented rock mass strain sensor measured strain at 100-cm intervals along a two anchor rock bolt grouted in the slope intact rock mass. In field testing, a number of transient signals have been observed, which in some cases were large enough to trigger rapid sampling. The combination of short- and long-term observation offers new insight into the slope stability and blasting cumulative effects. Therefore, FBG sensors are a useful tool for measuring in situ strain in intact rock masses.

  14. A Magnetostrictive Composite-Fiber Bragg Grating Sensor

    Science.gov (United States)

    Quintero, Sully M. M.; Braga, Arthur M. B.; Weber, Hans I.; Bruno, Antonio C.; Araújo, Jefferson F. D. F.

    2010-01-01

    This paper presents a light and compact optical fiber Bragg Grating sensor for DC and AC magnetic field measurements. The fiber is coated by a thick layer of a magnetostrictive composite consisting of particles of Terfenol-D dispersed in a polymeric matrix. Among the different compositions for the coating that were tested, the best magnetostrictive response was obtained using an epoxy resin as binder and a 30% volume fraction of Terfenol-D particles with sizes ranging from 212 to 300 μm. The effect of a compressive preload in the sensor was also investigated. The achieved resolution was 0.4 mT without a preload or 0.3 mT with a compressive pre-stress of 8.6 MPa. The sensor was tested at magnetic fields of up to 750 mT under static conditions. Dynamic measurements were conducted with a magnetic unbalanced four-pole rotor. PMID:22163644

  15. A Magnetostrictive Composite-Fiber Bragg Grating Sensor

    Directory of Open Access Journals (Sweden)

    Jefferson F. D. F. Araújo

    2010-08-01

    Full Text Available This paper presents a light and compact optical fiber Bragg Grating sensor for DC and AC magnetic field measurements. The fiber is coated by a thick layer of a magnetostrictive composite consisting of particles of Terfenol-D dispersed in a polymeric matrix. Among the different compositions for the coating that were tested, the best magnetostrictive response was obtained using an epoxy resin as binder and a 30% volume fraction of Terfenol-D particles with sizes ranging from 212 to 300 µm. The effect of a compressive preload in the sensor was also investigated. The achieved resolution was 0.4 mT without a preload or 0.3 mT with a compressive pre-stress of 8.6 MPa. The sensor was tested at magnetic fields of up to 750 mT under static conditions. Dynamic measurements were conducted with a magnetic unbalanced four-pole rotor

  16. Palladium coated fibre Bragg grating based hydrogen sensor

    International Nuclear Information System (INIS)

    Detection of steam generator leaks in fast nuclear reactors is carried out by monitoring hydrogen in argon cover-gas. Hydrogen released during sodium cleaning of fast reactor components is required to be monitored. Hydrogen sensors with good sensitivity, stability and response time are required for all the above applications. We report a new type of hydrogen sensor with a Fibre Bragg Grating (FBG) coated with palladium thin film which is used to detect the leak of hydrogen gas in the Steam Generator (SG) module of the Fast Breeder Reactor (FBR). If water leaks into sodium, it results in sodium-water reaction. In this reaction hydrogen and sodium hydroxide are formed. Due to the explosive risk of hydrogen system, hydrogen sensors are of great interest in this case. It is known that hydrogen forms an explosive mixture with air once its concentration exceeds beyond the explosion limit of four percent. The advantages of FBG based hydrogen sensor over the other hydrogen sensors are its inherent property of safety from sparking, immunity to ambient electromagnetic interference. The sensing mechanism in this device is based on mechanical strain that is induced in the palladium coating when it absorbs hydrogen. This process physically stretches the grating and causes the grating period and grating's refractive index, to change. The Bragg wavelength shift is directly proportional to the strain induced and can be directly related to the percentage of hydrogen exposure. The online monitoring of palladium thin film coating on FBG is carried out and recorded the wavelength change and strain induced on the FBG. A hydrogen sensor set up have been fabricated which consists of SS vessel of capacity 10 litres, provided with pressure gauge, Argon filling line with a valve, Hydrogen injection line with flange, a vent line with valve and Hydrogen sensor fixing point. The Palladium coated FBG based Hydrogen sensor is tested in this experimental facility in the exposure of hydrogen in

  17. Dynamic strain measurement of hydraulic system pipeline using fibre Bragg grating sensors

    Directory of Open Access Journals (Sweden)

    Qiang Wang

    2016-04-01

    Full Text Available Fatigue failure is a serious problem in hydraulic piping systems installed in the machinery and equipment working in harsh operational conditions. To alleviate this problem, health monitoring of pipes can be conducted by measuring and analysing vibration-induced strain. Fibre Bragg grating is considered as a promising sensing approach for dynamic load monitoring. In this article, dynamic strain measurements based on fibre Bragg grating sensors for small-bore metal pipes have been investigated. The quasi-distributed strain sensing of fibre Bragg grating sensors is introduced. Two comparison experiments were carried out under vibration and impact loads among the methods of electrical strain gauge, piezoelectric accelerometer and fibre Bragg grating sensor. Experimental results indicate that fibre Bragg grating sensor possesses an outstanding ability to resist electromagnetic interference compared with strain gauge. The natural frequency measurement results, captured by fibre Bragg grating sensor, agree well with the modal analysis results obtained from finite element analysis. In addition, the attached fibre Bragg grating sensor brings a smaller impact on the dynamic characteristics of the measured pipe than the accelerometer due to its small size and lightweight. Fibre Bragg grating sensors have great potential for the quasi-distributed measurement of dynamic strain for the dynamic characteristic research and health monitoring of hydraulic system pipeline.

  18. Miniature fiber Bragg grating sensor interrogator (FBG-Transceiver) system

    Science.gov (United States)

    Mendoza, Edgar A.; Kempen, Cornelia; Lopatin, Craig

    2007-04-01

    This paper describes recent progress conducted towards the development of a miniature fiber Bragg grating sensor interrogator (FBG-Transceiver TM) system based on multi-channel integrated optic sensor (InOSense TM) microchip technology. The hybrid InOSense TM microchip technology enables the integration of all of the functionalities, both passive and active, of conventional bench top FBG sensor interrogator systems, packaged in a miniaturized, low power operation, 2-cm x 5-cm package suitable for the long-term structural health monitoring in applications where size, weight, and power are critical for operation. The FBG-Transceiver system uses active optoelectronic components monolithically integrated to the InOSense TM microchip, a microprocessor controlled signal processing electronics board capable of processing the FBG sensors signals related to stress-strain and temperature as well as vibration and acoustics. The FBG-Transceiver TM system represents a new, reliable, highly robust technology that can be used to accurately monitor the status of an array of distributed fiber optic Bragg grating sensors installed in critical infrastructures. Its miniature package, low power operation, and state-of-the-art data communications architecture, all at a very affordable price makes it a very attractive solution for a large number of SHM/NDI applications in aerospace, naval and maritime industry, civil structures like bridges, buildings and dams, the oil and chemical industry, and for homeland security applications. The miniature, cost-efficient FBG-Transceiver TM system is poised to revolutionize the field of structural health monitoring and nondestructive inspection market. The sponsor of this program is NAVAIR under a DOD SBIR contract.

  19. Strain and temperature sensors using multimode optical fiber Bragg gratings and correlation signal processing

    OpenAIRE

    Lim, J; Yang, QP; Jones, BE; Jackson, PR

    2002-01-01

    Multimode fiber optic Bragg grating sensors for strain and temperature measurements using correlation signal processing methods have been developed. Two multimode Bragg grating sensors were fabricated in 62/125 m graded-index silica multimode fiber; the first sensor was produced by the holographic method and the second sensor by the phase mask technique. The sensors have signal reflectivity of approximately 35% at peak wavelengths of 835 nm and 859 nm, respectively. Strain testing...

  20. Structural Health Monitoring Using Fiber Bragg Grating Sensor Matrix Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Fiber Bragg Grating had been identified as very important elements, especially for strain measurements in smart structures. In many applications, arrays of FBG...

  1. Direct UV-written planar Bragg grating sensors

    International Nuclear Information System (INIS)

    Integrated photonics is a proven platform for physical and chemical sensing. It offers miniaturised solutions that are suited for use in extreme environments, including strong EM-fields, EM-pulses and contact with flammable materials, often far exceeding electronic sensors in this regard. This review looks into direct UV-written planar Bragg grating technology and its application to integrated photonic sensors. The platform has been demonstrated widely for measurement of physical properties such as temperature, pressure and strain. In addition, by using an evanescent interaction, refractive index can be measured allowing for chemical and biochemical detection. Further to this, the platform has recently been utilised in quantum information processing, where quantum gate operations and single photon detection has been shown. (topical review)

  2. A Method to Discriminate Strain and Temperature in Fiber Bragg Grating Sensors

    OpenAIRE

    Chalapati, Madhan T; Pattnaik, PK; Selvarajan, A; T. Srinivas

    2005-01-01

    A significant limitation to the applications of fiber Bragg gratings (FBG) sensors is the sensitivity of the Bragg wavelength to both temperature and strain, complicating the independent measurement of these paremeters. In this letter, we explore a new method to discriminate strain and temperature in FBG sensors, which utilises the additioanl wavelength dependent phase introduced by Fiber Bragg grating written on sensing arm of Mach Zehnder Interferometer (MZI). The intensity variations of th...

  3. Composite scarf repair monitoring using fiber Bragg grating sensors

    Science.gov (United States)

    Li, Henry C. H.; Herszberg, Israel; Davis, Claire E.; Stoddart, Paul R.

    2007-04-01

    Structural health monitoring (SHM) technology may be applied to composite bonded repairs to enable the continuous through-life assessment of the repair efficacy. This paper describes an SHM technique for the detection of debonding in composite scarf repairs using fibre optic Bragg grating strain sensors. A typical composite sandwich structure with a scarf repair on one surface is examined in this paper. A finite element study was conducted which showed that the strain in the debonded region changed significantly compared to the undamaged state. A differential strain approach was used to facilitate the detection of debonds, where two sensors were strategically positioned so that their strain differential increased as the damage propagated. With the use of matching gratings, this technique greatly reduced the support equipment requirement by converting the spectral information into an intensity-modulated signal, thus allowing a compact photodetector to be used for sensor interrogation. An experimental investigation was conducted to validate the theoretically predicted results. The experimental measurements agreed well with the numerical findings qualitatively, indicating that the proposed scheme has great potential as a simple and effective monitoring technique for composite scarf repairs.

  4. Structural Health Monitoring of a Tall Building during Construction with Fiber Bragg Grating Sensors

    OpenAIRE

    Li, D. S.; Ren, L.; Li, H. N.; Song, G. B.

    2012-01-01

    Fiber Bragg grating sensors demonstrate a great potential as a structural health monitoring tool for civil structures to ensure structural integrity, durability, and reliability. The advantages of applying fiber optic sensors to a tall building include their immunity to electromagnetic interference and their multiplexing ability to transfer optical signals over a long distance. In the work, fiber Bragg grating sensors, consisting of strain and temperature sensors, are applied to structural mo...

  5. Resonant THz sensor for paper quality monitoring using THz fiber Bragg gratings

    CERN Document Server

    Yan, Guofeng; Mikulic, Predrag; Bock, Wojtek J; Skorobogatiy, Maksim

    2013-01-01

    We report fabrication of THz fiber Bragg gratings (TFBG) using CO2 laser inscription on subwavelength step-index polymer fibers. A fiber Bragg grating with 48 periods features a ~4 GHz-wide stop band and ~15 dB transmission loss in the middle of a stop band. The potential of such gratings in design of resonant sensor for monitoring of paper quality is demonstrated. Experimental spectral sensitivity of the TFBG-based paper thickness sensor was found to be ~ -0.67 GHz / 10 um. A 3D electromagnetic model of a Bragg grating was used to explain experimental findings.

  6. The influence of adhesive on fiber Bragg grating strain sensor

    Science.gov (United States)

    Chen, Jixuan; Gong, Huaping; Jin, Shangzhong; Li, Shuhua

    2009-08-01

    A fiber Bragg grating (FBG) sensor was fixed on the uniform strength beam with three adhesives, which were modified acrylate, glass glue and epoxy resin. The influence of adhesive on FBG strain sensor was investigated. The strain of FBG sensor was varied by loading weight to the uniform strength beam. The wavelength shift of the FBG sensor fixed by the three kinds of adhesive were measured with different weight at the temperatures 0°C, 10°C, 20°C, 30°C, 40°C. The linearity, sensitivity and their stability at different temperature of FBG sensor which fixed by every kind of adhesives were analyzed. The results show that, the FBG sensor fixed by the modified acrylate has a high linearity, and the linear correlation coefficient is 0.9996. It also has a high sensitivity which is 0.251nm/kg. The linearity and the sensitivity of the FBG sensor have a high stability at different temperatures. The FBG sensor fixed by the glass glue also has a high linearity, and the linear correlation coefficient is 0.9986, but it has a low sensitivity which is only 0.041nm/kg. The linearity and the sensitivity of the FBG sensor fixed by the glass glue have a high stability at different temperatures. When the FBG sensor is fixed by epoxy resin, the sensitivity and linearity is affected significantly by the temperature. When the temperature changes from 0°C to 40°C, the sensitivity decreases from 0.302nm/kg to 0.058nm/kg, and the linear correlation coefficient decreases from 0.9999 to 0.9961.

  7. An experimental approach to quantify strain transfer efficiency of fibre bragg grating sensors to host structures

    OpenAIRE

    C. Y. Wei; Ye, Chen-Chun; James, Stephen W.; Tatam, Ralph P.; Irving, Phil E.

    2001-01-01

    This paper developed a method to evaluate the strain transfer efficiency of fibre Bragg grating sensors to host structures. Various coatings were applied to fibre Bragg grating sensors after being fabricated. They were epoxy, silane agent and polypropylene, representing different surface properties. A neat epoxy resin plate was used as the host in which the coated fibre sensors were embedded in the central layer. The tensile strain output from the FBGs was compared with that...

  8. Karakterisasi Fiber Bragg Grating (FBG) Untuk Pengembangan Sistem Sensor Strain Tanah

    OpenAIRE

    Sinuhaji, Depi Santi

    2010-01-01

    Fiber Bragg Grating (FBG) is a periodic change of refractive index which is the length of optical fiber. Has been developed Fiber Bragg Grating (FBG)-based laser diodes for monitoring landslide-prone areas. This sensor has been developed because high sensitivity and is not affected by electromagnetic induction that can be placed at a distance from the location where the power supply and monitor. FBG transmission peak will shift when the grating is change resulting from a change in temperature...

  9. Development of a Fibre Bragg Grating Sensor for Rock Deformation Monitoring

    Science.gov (United States)

    Kanopoulos, Patrick Paskalis

    This thesis examines the theoretical and experimental performance of a fibre Bragg grating sensor for static and dynamic strain measurement in hard rock. A literature review focuses on the fundamental theory of fibre Bragg gratings, various physical demodulation schemes used to interrogate Bragg sensors with an emphasis on charge coupled device spectrometry, as well as the aliasing behaviour of Bragg gratings as sensors. A coupled numerical-analytical analysis is conducted on various sensor configurations designed for borehole deployment in order to establish the response of the strain sensors under various strain conditions. The findings of an experimental investigation of two sensors subjected to uniaxial strain within a grout and a rock specimen are presented. The experimental data confirm the feasibility of using the proposed sensor as a part of an integrated optical strain sensing network.

  10. The Functionality of Fiber Bragg Grating Sensor Compared to that of Foil Gauge

    Directory of Open Access Journals (Sweden)

    Bashir A. Tahir

    2005-01-01

    Full Text Available Technology such as Fiber Bragg Grating (FBG sensors are widely accepted in almost all industries. FBG are being investigated for their applicability in other markets such as smart structures. Fiber optic sensors can also be used in many different applications. Fiber optic sensors are available in several types; among them, the Bragg grating sensor is being studied in this research. For this research work, the main focus was the use of fiber Bragg grating sensors for measuring strain. The key objective of this research; to determine the functionality of fiber Bragg grating sensors compared to that of conventional foil gauges. Fiber Bragg grating sensors were chosen for this research because they have a high potential for various uses in the monitoring of smart structures. The major incentives for this type of research are the current deterioration of civil structures in west Malaysia. The laboratory tests are being reported in this research work including tests of steel straps and an aluminum test specimen. In all the tests, strain was measured using the fiber Bragg grating sensors and compared to values from a conventional foil gauge. The results are being discussed in details. It was inferred that the use of fiber optic technology for the monitoring of civil structures is very promising and the future is sure to bring further advancements and improvements.

  11. Bragg Grating Based Sensors in Microstructured Polymer Optical Fibers: Accelerometers and Microphones

    DEFF Research Database (Denmark)

    Stefani, Alessio

    With the growing interest towards fiber Bragg grating sensors and the growing ability in manufacturing polymer optical fibers, the development of polymer fiber Bragg sensors has catched the attention of industries with the goal of developing high performance sensors. This thesis presents...... the development of fiber sensors based on polymer optical fiber Bragg gratings. The whole process from the preform to the device is discussed and reported. A presentation on the fiber drawing technique used is given. Issues encountered when working with polymer fibers and solutions concerning fiber cleaving...... gratings is shown and temperature compensation of strain sensors, by using two adjacent gratings, is demonstrated. Humidity insensitivity in a strain sensor based on a TOPAS fiber is also shown. In order to investigate the possibility of using viscoelastic materials, such as polymers, in dynamic sensors...

  12. A Novel Fiber Bragg Grating with Triangular Spectrum and Its Application in Strain Sensor

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel fiber Bragg grating with triangular spectrum is presented. A strain sensor based on this fiber grating is proposed. Experiments showed that the sensor has advantages of high sensitivity, wider measuring range and immunity to fluctuation of the light source power.

  13. Dynamic Landslide Deformation Monitoring with Fiber Bragg Grating Sensors

    Science.gov (United States)

    Moore, J. R.; Gischig, V.; Button, E.; Loew, S.

    2009-12-01

    Fiber optic (FO) strain sensors are a promising new technology for in-situ landslide monitoring. General performance advantages include high resolution, fast sampling rate, and insensitivity to electrical disturbances. Here we describe a new FO monitoring system based on long-gage fiber Bragg grating sensors installed at the Randa Rockslide Laboratory in southern Switzerland. We highlight the advantages and disadvantages of the system, describe relevant first results, and compare FO data to that from traditional instruments already installed on site. The Randa rock slope has been the subject of intensive research since its failure in 1991. Around 5 million cubic meters of rock remains unstable today, moving at rates up to 20 mm / year. Traditional in-situ monitoring techniques have been employed to understand the mechanics and driving forces of the currently unstable rock mass, however these investigations are limited by the resolution and low sampling rate of the sensors. The new FO monitoring system has micro-strain resolution and offers the capability to detect sub-micrometer scale deformations in both triggered-dynamic and continuous measurements. Two types of sensors have been installed: fully-embedded borehole sensors encased in grout at depths of 38, 40, and 68 m, and surface extensometers spanning active tension cracks. Dynamic measurements are triggered by sensor deformation and recorded at 100 Hz, while continuous measurements are logged every 5 minutes. Since installation in August 2008, the FO monitoring system has been operational 90% of the time. Time series deformation data show movement rates consistent with previous borehole extensometer surveys. Accelerated displacements following installation are likely related to long-term curing and dewatering of the grout. A number of interesting transients have been recorded, which in some cases were large enough to trigger rapid sampling. The combination of short- and long-term observation offers new

  14. Wavelength interrogation of fiber Bragg grating sensors using tapered hollow Bragg waveguides.

    Science.gov (United States)

    Potts, C; Allen, T W; Azar, A; Melnyk, A; Dennison, C R; DeCorby, R G

    2014-10-15

    We describe an integrated system for wavelength interrogation, which uses tapered hollow Bragg waveguides coupled to an image sensor. Spectral shifts are extracted from the wavelength dependence of the light radiated at mode cutoff. Wavelength shifts as small as ~10  pm were resolved by employing a simple peak detection algorithm. Si/SiO₂-based cladding mirrors enable a potential operational range of several hundred nanometers in the 1550 nm wavelength region for a taper length of ~1  mm. Interrogation of a strain-tuned grating was accomplished using a broadband amplified spontaneous emission (ASE) source, and potential for single-chip interrogation of multiplexed sensor arrays is demonstrated. PMID:25361125

  15. Modelling and Simulation of Temperature Sensitivity of Bragg Grating Sensor for Structural Health Monitoring Application

    Directory of Open Access Journals (Sweden)

    Bilkish Mondal

    2014-03-01

    Full Text Available Here in this paper we presented the modelling of Fiber Bragg Grating (FBG as temperature sensor for structural health monitoring application is geometrically designed in the wavelength window of 1.568-1.580μm. Simulation has been done by using optical software R-Soft (GratingMOD.

  16. A Distributed Fibre Bragg Grating Sensor Interrogator Employing a Reformative Arrayed Waveguide Grating

    Institute of Scientific and Technical Information of China (English)

    HUANG Jing-Tang; HUANG Xu-Guang; ZHAO Hua-Wei

    2008-01-01

    @@ We present an interrogating technique employing a reformative arrayed waveguide grating without output waveguides in combination with a linear charge coupled device. A simple and effective data processing method called area equalized point is used to improve the system resolution. The simulation results show that the wavelength shift of a fibre Bragg grating with temperature can be precisely measured by this interrogation technique. The temperature accuracy and wavelength resolution of the sensor system are smaller than 0.08℃ and 0.8 pm, respectively. If the FBG 3dB-bandwidth is 0.2nm with the wavelength spacing between two adjacent FBGs of 1.4 nm, the temperature and wavelength errors caused by croestalk are respectively 0.01℃ and 0. 1 pm.

  17. Interrogating a Fiber Bragg Grating Vibration Sensor by Narrow Line Width Light

    Institute of Scientific and Technical Information of China (English)

    Jun Chang; Dian-Heng Huo; Liang-Zhu Ma; Xiao-Hui Liu; Tong-Yu Liu; Chang Wang

    2008-01-01

    A method to interrogate fiber Bragg grating vibration sensor by narrow line width light is demonstrated. The interrogation scheme takes advantage of the intensity modulation of narrow spectral bandwidth light, such as distributed feedback laser, when a reflection or transmission spectrum curve of an fiber Bragg grating (FBG) moves due to the strain which is applied on the sensor. The sensor's response to accelerating frequency and amplitude is measured by experiment. The factors which have impacts on the sensitivity of the interrogation system are also discussed.

  18. Humidity insensitive TOPAS polymer fiber Bragg grating sensor

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Khan, Lutul; Webb, David J.;

    2011-01-01

    We report the first experimental demonstration of a humidity insensitive polymer optical fiber Bragg grating (FBG), as well as the first FBG recorded in a TOPAS polymer optical fiber in the important low loss 850nm spectral region. For the demonstration we have fabricated FBGs with resonance...... wavelength around 850 nm and 1550 nm in single-mode microstructured polymer optical fibers made of TOPAS and the conventional poly (methyl methacrylate) (PMMA). Characterization of the FBGs shows that the TOPAS FBG is more than 50 times less sensitive to humidity than the conventional PMMA FBG in both...

  19. Underwater Acoustic Sensors Based on Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Giuseppe Parente

    2009-06-01

    Full Text Available We report on recent results obtained with a fiber optic hydrophone based on the intensity modulation of the laser light in a FBG (Fiber Bragg Grating under the influence of the sound pressure. In order to control the behavior of the hydrophone in terms of sensitivity and bandwidth, FBGs have been coated with proper materials, characterized by different elastic modulus and shapes. In particular, new experiments have been carried out using a cylindrical geometry with two different coating, showing that the sensitivity is not influenced by the shape but by the transversal dimension and the material characteristics of the coating.

  20. Dynamic gate algorithm for multimode fiber Bragg grating sensor systems.

    Science.gov (United States)

    Ganziy, D; Jespersen, O; Woyessa, G; Rose, B; Bang, O

    2015-06-20

    We propose a novel dynamic gate algorithm (DGA) for precise and accurate peak detection. The algorithm uses a threshold-determined detection window and center of gravity algorithm with bias compensation. We analyze the wavelength fit resolution of the DGA for different values of the signal-to-noise ratio and different peak shapes. Our simulations and experiments demonstrate that the DGA method is fast and robust with better stability and accuracy than conventional algorithms. This makes it very attractive for future implementation in sensing systems, especially based on multimode fiber Bragg gratings. PMID:26193010

  1. High-sensitivity temperature sensor based on Bragg grating in BDK-doped photosensitive polymer optical fiber

    Institute of Scientific and Technical Information of China (English)

    Xusheng Cheng; Weiwei Qiu; Wenxuan Wu; Yanhua Luo; Xiujie Tian; Qijin Zhang; Bing Zhu

    2011-01-01

    @@ A single-mode polymer optical fiber (POF) with highly photosensitive core doped with benzil dimethyl ketal (BDK) is fabricated and used for writing Bragg grating through the two-beam interference method. The Bragg wavelength of the grating is about 1570 nm, while the full-width at half-maximum (FWHM) of the reflection peak is 0.3 nm. The temperature response of POF Bragg grating is theoretically analyzed and experimentally measured in contrast to silica optical fiber Bragg grating (FBG). The result shows that the temperature character of POF Bragg grating is negative, which is opposite to the silica optical FBG. The absolute value of the temperature response of POF Bragg grating is one order of magnitude higher than that of the silica optical FBG, making POF Bragg grating appear to be very attractive for constructing temperature sensors with high resolution.%A single-mode polymer optical fiber (POF) with highly photosensitive core doped with benzil dimethyl ketal (BDK) is fabricated and used for writing Bragg grating through the two-beam interference method. The Bragg wavelength of the grating is about 1570 nm, while the full-width at half-maximum (FWHM) of the reflection peak is 0.3 nm. The temperature response of POF Bragg grating is theoretically analyzed and experimentally measured in contrast to silica optical fiber Bragg grating (FBG). The result shows that the temperature character of POF Bragg grating is negative, which is opposite to the silica optical FBG. The absolute value of the temperature response of POF Bragg grating is one order of magnitude higher than that of the silica optical FBG, making POF Bragg grating appear to be very attractive for constructing temperature sensors with high resolution.

  2. Feasibility of Fiber Bragg Grating and Long-Period Fiber Grating Sensors under Different Environmental Conditions

    Directory of Open Access Journals (Sweden)

    Jian-Neng Wang

    2010-11-01

    Full Text Available This paper presents the feasibility of utilizing fiber Bragg grating (FBG and long-period fiber grating (LPFG sensors for nondestructive evaluation (NDE of infrastructures using Portland cement concretes and asphalt mixtures for temperature, strain, and liquid-level monitoring. The use of hybrid FBG and LPFG sensors is aimed at utilizing the advantages of two kinds of fiber grating to implement NDE for monitoring strains or displacements, temperatures, and water-levels of infrastructures such as bridges, pavements, or reservoirs for under different environmental conditions. Temperature fluctuation and stability tests were examined using FBG and LPFG sensors bonded on the surface of asphalt and concrete specimens. Random walk coefficient (RWC and bias stability (BS were used for the first time to indicate the stability performance of fiber grating sensors. The random walk coefficients of temperature variations between FBG (or LPFG sensor and a thermocouple were found in the range of −0.7499 °C/ to −1.3548 °C/. In addition, the bias stability for temperature variations, during the fluctuation and stability tests with FBG (or LPFG sensors were within the range of 0.01 °C/h with a 15–18 h time cluster to 0.09 °C/h with a 3–4 h time cluster. This shows that the performance of FBG or LPFG sensors is comparable with that of conventional high-resolution thermocouple sensors under rugged conditions. The strain measurement for infrastructure materials was conducted using a packaged FBG sensor bonded on the surface of an asphalt specimen under indirect tensile loading conditions. A finite element modeling (FEM was applied to compare experimental results of indirect tensile FBG strain measurements. For a comparative analysis between experiment and simulation, the FEM numerical results agreed with those from FBG strain measurements. The results of the liquid-level sensing tests show the LPFG-based sensor could discriminate five stationary liquid

  3. Aviation Fuel Gauging Sensor Utilizing Multiple Diaphragm Sensors Incorporating Polymer Optical Fiber Bragg Gratings

    DEFF Research Database (Denmark)

    Marques, C. A. F.; Pospori, A.; Saez-Rodriguez, D.;

    2016-01-01

    A high-performance fuel gauging sensor is described that uses five diaphragm-based pressure sensors, which are monitored using a linear array of polymer optical fiber Bragg gratings. The sensors were initially characterized using water, revealing a sensitivity of 98 pm/cm for four of the sensors...... and 86 pm/cm for the fifth. The discrepancy in the sensitivity of the fifth sensor has been explained as being a result of the annealing of the other four sensors. Initial testing in JET A-1 aviation fuel revealed the unsuitability of silicone rubber diaphragms for prolonged usage in fuel. A second set...... of sensors manufactured with a polyurethane-based diaphragm showed no measurable deterioration over a three month period immersed in fuel. These sensors exhibited a sensitivity of 39 pm/cm, which is less than the silicone rubber devices due to the stiffer nature of the polyurethane material used....

  4. Dual Measurements of Pressure and Temperature With Fiber Bragg Grating Sensor

    OpenAIRE

    Tahreer S. Mansour; Fahad M. Abdulhussein

    2015-01-01

    The fiber Bragg grating (FBG) technology has been rapidly applied in the sensing technology field. In this work, uniform FBG was used as pressure sensor based on measuring related Bragg wavelength shift. The pressure was applied directly by air compressor to the sensor and the pressure was ranged from 1 to 6 bar. This sensor also was affected by the external temperature so as a result it could be used as a temperature sensor. This sensor could be used to monitor the pressure of dams. It has b...

  5. Magnetic field sensor based on fiber Bragg grating with a spiral microgroove ablated by femtosecond laser.

    Science.gov (United States)

    Dai, Yutang; Yang, Minghong; Xu, Gang; Yuan, Yinquan

    2013-07-15

    A novel magnetic field sensor based on Terfenol-D coated fiber Bragg grating with spiral microstructure was proposed and demonstrated. Through a specially-designed holder, the spiral microstructure was ablated into the fiber Bragg grating (FBG) cladding by femtosecond laser. Due to the spiral microstructure, the sensitivity of FBG coated with magnetostrictive film was enhanced greatly. When the spiral pitch is 50 μm and microgroove depth is 13.5 μm, the sensitivity of the magnetic field sensor is roughly 5 times higher than that of non-microstructured standard FBG. The response to magnetic field is reversible, and could be applicable for magnetic field detection.

  6. Fiber optic Bragg grating sensor network installed in a concrete road bridge

    Science.gov (United States)

    Maaskant, Robert; Alavie, A. Tino; Measures, Raymond M.; Ohn, Myo M.; Karr, Shawn E.; Glennie, Derek J.; Wade, C.; Tadros, Gamil; Rizkalla, Sami

    1994-05-01

    The installation of a fiber optic Bragg grating strain sensor network in a new road bridge is described. These sensors are attached to prestressing tendons embedded in prefabricated concrete girders. Three types of prestressing tendons are being monitored: conventional steel strand and two types of carbon fibers reinforced plastic tendons. Sensor durability issues are reviewed and the installation is described. Initial measurements indicate that the sensors are operational and provide some early comparison of tendon performance.

  7. A Noncontact Force Sensor Based on a Fiber Bragg Grating and Its Application for Corrosion Measurement

    OpenAIRE

    Antonio C. Bruno; Clara J. Pacheco

    2013-01-01

    A simple noncontact force sensor based on an optical fiber Bragg grating attached to a small magnet has been proposed and built. The sensor measures the force between the magnet and any ferromagnetic material placed within a few millimeters of the sensor. Maintaining the sensor at a constant standoff distance, material loss due to corrosion increases the distance between the magnet and the corroded surface, which decreases the magnetic force. This will decrease the strain in the optical fiber...

  8. A temperature insensitive Bragg grating sensor - using orthogonal polar polarisation modes for in situ temperature compensation

    OpenAIRE

    Parker, R M; J.C.Gates; Grossel, M. C.; P.G.R.Smith

    2010-01-01

    An exposed Bragg grating incorporated into a planar waveguide forms an optical device that acts as a refractive index sensor. The exposed evanescent field causes the Bragg peak to be sensitive to the refractive index of its surroundings and can be used to detect changes in this environment. The method reported is able to provide accurate temperature compensation by applying a scaling factor derived from measurement of the birefringence of the transverse electric (TE) and transverse magnetic (...

  9. Humidity insensitive step-index polymer optical fibre Bragg grating sensors

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Fasano, Andrea; Stefani, Alessio;

    2015-01-01

    We have fabricated and characterised a humidity insensitive step index(SI) polymer optical fibre(POF) Bragg grating sensors. The fibre was made based on the injection molding technique, which is an efficient method for fast, flexible and cost effective preparation of the fibre preform...

  10. Polymer PCF Bragg grating sensors based on poly(methyl methacrylate) and TOPAS cyclic olefin copolymer

    DEFF Research Database (Denmark)

    Johnson, Ian P; Webb, David J; Kalli, Kyriacos;

    2011-01-01

    Fibre Bragg grating (FBG) sensors have been fabricated in polymer photonic crystal fibre (PCF). Results are presented using two different types of polymer optical fibre (POF); first multimode PCF with a core diameter of 50μm based on poly(methyl methacrylate) (PMMA) and second, endlessly single m...

  11. 3D flexible needle steering in soft-tissue phantoms using fiber bragg grating sensors

    NARCIS (Netherlands)

    Abayazid, Momen; Kemp, Marco; Misra, Sarthak

    2013-01-01

    Needle insertion procedures are commonly used for surgical interventions. In this paper, we develop a three-dimensional (3D) closed-loop control algorithm to robotically steer flexible needles with an asymmetric tip towards a target in a soft-tissue phantom. Twelve Fiber Bragg Grating (FBG) sensors

  12. Applicability of a vibration sensor based on the optical fiber Bragg grating in radiation environment

    CERN Document Server

    Fujita, K; Nakazawa, M; Takahashi, H

    2003-01-01

    Fiber Bragg grating (FBG) is a kind of an optical device developing rapidly in these years and it has various excellent characteristics as a sensor. To investigate applicability of FBG as vibration sensor to nuclear plants, measurement systems were developed and tested. As a result, the FBGs could detect vibration even in gamma-ray environment. Moreover, vibration of a component around a cooling system at the YAYOI reactor could be detected successfully with FBG based sensors.

  13. Comparison of recoated fiber Bragg grating sensors under tension on a steel coupon

    Science.gov (United States)

    Rivera, E.; Thomson, D. J.; Mufti, A. A.

    2005-05-01

    One of the key elements in a structural health monitoring system is the sensing element and data acquisition system. One type of fiber optic sensor used to measure strain is the fiber Bragg grating. Bragg gratings are fabricated using different methods. One method involves placing a mask pattern over the optical fiber and projecting UV light through it to change the refractive index of the core. However, before the grating is written into the core of the fibre, the outer fibre coatings must be stripped away either mechanically or chemically. Fibre Bragg gratings are then recoated after the grating has been written to maintain the strength and flexibility of the fibre by protecting the exposed glass from damage. Acrylate and polyimide are two types of recoat material typically used on fibre Bragg grating sensors. This work is a controlled comparison of polyimide and acrylate recoated fibres for Bragg grating strain sensors. The comparison was carried out using a tension test coupon with recoated FBG and electrical strain gauges bonded to its surface. The tension test specimen was made of cold rolled steel and was designed according to ASTM A30-97a standard. The dimensions were chosen such that three fibre optic sensors and a strain gauge can be attached on each side. The load was applied in 40 μɛ steps until the strain reached approximately 200 ´ɛ. The load was then incrementally decreased back to zero. FBG sensors from 2 manufacturers were compared. For the first manufacturer the Acrylate coated sensors required a gauge factor is 0.75 in order for electrical and FBG strain readings to agree. For Polyimide coated sensors, the appropriate gauge factor was very close to the theoretically predicted value of 0.8. Using these gauge factors, the error between the first manufacturers sensor readings and the strain gauges was well within +/-5´ɛ. On the other hand, the second manufacturers sensors did not perform nearly as well. Their readings were substantially lower

  14. Orientation-Dependent Displacement Sensor Using an Inner Cladding Fiber Bragg Grating.

    Science.gov (United States)

    Yang, Tingting; Qiao, Xueguang; Rong, Qiangzhou; Bao, Weijia

    2016-01-01

    An orientation-dependent displacement sensor based on grating inscription over a fiber core and inner cladding has been demonstrated. The device comprises a short piece of multi-cladding fiber sandwiched between two standard single-mode fibers (SMFs). The grating structure is fabricated by a femtosecond laser side-illumination technique. Two well-defined resonances are achieved by the downstream both core and cladding fiber Bragg gratings (FBGs). The cladding resonance presents fiber bending dependence, together with a strong orientation dependence because of asymmetrical distribution of the "cladding" FBG along the fiber cross-section. PMID:27626427

  15. Orientation-Dependent Displacement Sensor Using an Inner Cladding Fiber Bragg Grating

    Science.gov (United States)

    Yang, Tingting; Qiao, Xueguang; Rong, Qiangzhou; Bao, Weijia

    2016-01-01

    An orientation-dependent displacement sensor based on grating inscription over a fiber core and inner cladding has been demonstrated. The device comprises a short piece of multi-cladding fiber sandwiched between two standard single-mode fibers (SMFs). The grating structure is fabricated by a femtosecond laser side-illumination technique. Two well-defined resonances are achieved by the downstream both core and cladding fiber Bragg gratings (FBGs). The cladding resonance presents fiber bending dependence, together with a strong orientation dependence because of asymmetrical distribution of the “cladding” FBG along the fiber cross-section. PMID:27626427

  16. Fiber Optic Fabry-Perot Current Sensor Integrated with Magnetic Fluid Using a Fiber Bragg Grating Demodulation

    OpenAIRE

    Ji Xia; Qi Wang; Xu Liu; Hong Luo

    2015-01-01

    An optical fiber current sensor based on Fabry-Perot interferometer using a fiber Bragg grating demodulation is proposed. Magnetic fluid is used as a sensitive medium in fiber optical Fabry-Perot (F-P) cavity for the optical characteristic of magnetic-controlled refractive index. A Fiber Bragg grating (FBG) is connected after the F-P interferometer which is used to reflect the optical power at the Bragg wavelength of the interference transmission spectrum. The corresponding reflective power o...

  17. Railway track component condition monitoring using optical fibre Bragg grating sensors

    International Nuclear Information System (INIS)

    The use of optical fibre Bragg grating (FBG) strain sensors to monitor the condition of safety critical rail components is investigated. Fishplates, switchblades and stretcher bars on the Stagecoach Supertram tramway in Sheffield in the UK have been instrumented with arrays of FBG sensors. The dynamic strain signatures induced by the passage of a tram over the instrumented components have been analysed to identify features indicative of changes in the condition of the components. (paper)

  18. Railway track component condition monitoring using optical fibre Bragg grating sensors

    Science.gov (United States)

    Buggy, S. J.; James, S. W.; Staines, S.; Carroll, R.; Kitson, P.; Farrington, D.; Drewett, L.; Jaiswal, J.; Tatam, R. P.

    2016-05-01

    The use of optical fibre Bragg grating (FBG) strain sensors to monitor the condition of safety critical rail components is investigated. Fishplates, switchblades and stretcher bars on the Stagecoach Supertram tramway in Sheffield in the UK have been instrumented with arrays of FBG sensors. The dynamic strain signatures induced by the passage of a tram over the instrumented components have been analysed to identify features indicative of changes in the condition of the components.

  19. Bragg gratings in Topas

    DEFF Research Database (Denmark)

    Zhang, C.; Webb, D.J.; Kalli, K.;

    We report for the first time fibre Bragg grating inscription in microstructured optical fibre fabricated from Topas® cyclic olefin copolymer. The temperature sensitivity of the grating was studied revealing a positive Bragg wavelength shift of approximately 0.8 nmK-1,the largest sensitivity yet...

  20. Fiber Optic Vibration Sensor Based on the Tilted Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Jiali An

    2013-01-01

    Full Text Available A temperature-insensitive fiber optic vibration sensor based on the tilted fiber Bragg grating (TFBG is presented. The sensing head is formed by insertion of a small section of MMF between a single-mode fiber and the TFBG. The reflection light from this tilted fiber Bragg grating includes two parts: the reflected Bragg mode and the cladding modes. The cladding modes were coupled back into the core mode as a function of the multimode fiber. The power of the cladding modes is sensitive to vibration, so the external vibration measurement can be obtained through the cladding mode average output power. Experiment results show that the root mean square (RMS of the detection error of the average power was 0.01 μW within the temperature range from 20 to 70°C, so it is proved to be temperature independent; its frequency response has been tested to 1 KHz.

  1. Dynamic strain detection using a fiber Bragg grating sensor array for geotechnical applications

    Science.gov (United States)

    Schmidt-Hattenberger, Cornelia; Naumann, M.; Borm, Gunter

    2003-03-01

    In recent years fiber Bragg gratings have been successfully introduced as sensors for strain, temperature and pressure variations. Their performance and reliability has been proven in many practical applications including strain monitoring in civil engineering and tunneling, downhole monitoring in oil reservoirs and flow assurance monitoring in pipelines. The gratings have great potential to at as true structurally integrated sensor elements. They can be embedded in typical structural or reinforcing elements of civil and geotechnical buildings. Several methods of interrogation schemes are established depending on the desired accuracy and resolution of the measurement. The most important methods are the linear discriminator, the tunable Fbry-Perot filter technique, and several interferometer setups.

  2. Dual Measurements of Pressure and Temperature With Fiber Bragg Grating Sensor

    Directory of Open Access Journals (Sweden)

    Tahreer S. Mansour

    2015-06-01

    Full Text Available The fiber Bragg grating (FBG technology has been rapidly applied in the sensing technology field. In this work, uniform FBG was used as pressure sensor based on measuring related Bragg wavelength shift. The pressure was applied directly by air compressor to the sensor and the pressure was ranged from 1 to 6 bar. This sensor also was affected by the external temperature so as a result it could be used as a temperature sensor. This sensor could be used to monitor the pressure of dams. It has been shown from the result that the sensor is very sensitive to the pressure and the sensitivity was (67 pmar and is very sensitive to temperature and the sensitivity was (10pm oC.

  3. A Noncontact Force Sensor Based on a Fiber Bragg Grating and Its Application for Corrosion Measurement

    Directory of Open Access Journals (Sweden)

    Antonio C. Bruno

    2013-08-01

    Full Text Available A simple noncontact force sensor based on an optical fiber Bragg grating attached to a small magnet has been proposed and built. The sensor measures the force between the magnet and any ferromagnetic material placed within a few millimeters of the sensor. Maintaining the sensor at a constant standoff distance, material loss due to corrosion increases the distance between the magnet and the corroded surface, which decreases the magnetic force. This will decrease the strain in the optical fiber shifting the reflected Bragg wavelength. The measured shift for the optical fiber used was 1.36 nm per Newton. Models were developed to optimize the magnet geometry for a specific sensor standoff distance and for particular corrosion pit depths. The sensor was able to detect corrosion pits on a fuel storage tank bottom with depths in the sub-millimeter range.

  4. Multi-Stress Monitoring System with Fiber-Optic Mandrels and Fiber Bragg Grating Sensors in a Sagnac Loop

    OpenAIRE

    Hyunjin Kim; Umesh Sampath; Minho Song

    2015-01-01

    Fiber Bragg grating sensors are placed in a fiber-optic Sagnac loop to combine the grating temperature sensors and the fiber-optic mandrel acoustic emission sensors in single optical circuit. A wavelength-scanning fiber-optic laser is used as a common light source for both sensors. A fiber-optic attenuator is placed at a specific position in the Sagnac loop in order to separate buried Bragg wavelengths from the Sagnac interferometer output. The Bragg wavelength shifts are measured with scanni...

  5. A high sensitive fiber Bragg grating strain sensor with automatic temperature compensation

    Institute of Scientific and Technical Information of China (English)

    Kuo Li; Zhen'an Zhou

    2009-01-01

    A high sensitive fiber Bragg grating (FBG) strain sensor with automatic temperature compensation is demonstrated. FBG is axially linked with a stick and their free ends are fixed to the measured object. When the measured strain changes, the stick does not change in length, but the FBG does. When the temperature changes, the stick changes in length to pull the FBG to realize temperature compensation. In experiments, 1.45 times strain sensitivity of bare FBG with temperature compensation of less than 0.1 nm Bragg wavelength drift over 100℃ shift is achieved.

  6. Liquid Resin Infusion process monitoring with embedded superimposed long period and short period Bragg grating sensor.

    Directory of Open Access Journals (Sweden)

    Robert L.

    2010-06-01

    Full Text Available We propose here the monitoring of the Liquid Resin Infusion (LRI process for using a superimposed long period (LPG and short period (FBG Bragg grating sensor. Monitoring of such a process is usually made measuring simultaneously temperature and strain by the use of an electro-optical device (FBG-Thermocouple. It has been shown that an applied solicitation is measured by a wavelength shift with a different sensitivity for LPG and FBG; thus strain and temperature influences can be determined separately by measuring corresponding wavelength shifts. The reported configuration is based on the use of these two Bragg gratings types written in the same fibre section, which allows us to discriminate the contributions of the temperature and strain. The sensor is embedded in a composite specimen manufactured by LRI process for monitoring in real time and simultaneously the applied temperature and strain.

  7. Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Montanini, Roberto; Recupero, Antonino; De Domenico, Fabrizio; Freni, Fabrizio

    2016-01-01

    Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data. PMID:27669251

  8. Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Montanini, Roberto; Recupero, Antonino; De Domenico, Fabrizio; Freni, Fabrizio

    2016-09-22

    Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data.

  9. Measurement Model for the Maximum Strain in Beam Structures Using Multiplexed Fiber Bragg Grating Sensors

    OpenAIRE

    Se Woon Choi; Jihoon Lee; Bo Hwan Oh; Hyo Seon Park

    2013-01-01

    This study develops a strain measurement model for beam structures subjected to multiloading conditions by defining the strain-shape function and participation factors to overcome the limitations of strain measurements using fiber Bragg grating (FBG) strain sensors. Using the proposed model, the maximum strain in a beam is obtained by the sum of the strains caused by the different loadings acting separately. In this paper, the strain-shape functions for various loading and support conditions ...

  10. Structural monitoring system with fiber Bragg grating sensors: Implementation and software solution

    CERN Document Server

    Fedorov, Aleksey; Makhrov, Ilya; Pozhar, Nikolay; Anufriev, Maxim; Pnev, Alexey; Karasik, Valeriy

    2014-01-01

    We present a structural health monitoring system for nondestructive testing of composite materials based on the fiber Bragg grating sensors and specialized software solution. Developed structural monitoring system has potential applications for preliminary tests of novel composite materials as well as real-time structural health monitoring of industrial objects. The software solution realizes control for the system, data processing and alert of an operator.

  11. A Fiber-Optical Intrusion Alarm System Based on Quasi-Distributed Fiber Bragg Grating Sensors

    Institute of Scientific and Technical Information of China (English)

    Qi Jiang; Yun-Jiang Rao; De-Hong Zeng

    2008-01-01

    A fiber-optical intrusion alarm system based on quasi-distributed fiber Bragg grating (FBG) sensors is demonstrated in this paper. The algorithms of empirical mode decomposition (EMD) and wavelet packet characteristic entropy are adopted to determine the intrusion location. The intrusion alarm software based on the Labview is developed, and it is also proved by the experiments. The results show that such a fiber-optical intrusion alarm system can offer the automatic intrusion alarm in real-time.

  12. Magneto-Optic Fiber Bragg Gratings with Application to High-Resolution Magnetic Field Sensors

    Institute of Scientific and Technical Information of China (English)

    Bao-Jian Wu; Ying Yang; Kun Qiu

    2008-01-01

    Magneto-optic fiber Bragg gratings (MFBG) based on magneto-optic materials have a lot of potential applications for sensing and optical signal processing. The transmission and reflection spectra of guided optical waves in the MFBG are investigated. According to the sensitivity of MFBG spectral lines to the magneto-optic coupling intensity varying with applied magnetic field, a novel magnetic field sensor of high-resolution up to 0.01 nm/(kA/m) is predicted.

  13. Monitoring damage development in composite repairs using chirped fibre Bragg grating sensors.

    OpenAIRE

    Rito, Rodolfo N.L.

    2015-01-01

    Composite repairs are often used for damaged structures in order to recover the mechanical properties of the original structure. During service, there is the possibility that damage will occur in the repaired region and hence it would be useful to be able to monitor such repairs. This research investigates the use of chirped fibre Bragg grating (CFBG) sensors to monitor the development of fatigue damage initiation and growth in the repaired region of three different repair systems, i.e. glass...

  14. Strain measurements on concrete beam and carbon fiber cable with distributed optical fiber Bragg grating sensors

    Science.gov (United States)

    Nellen, Philipp M.; Bronnimann, Rolf; Sennhauser, Urs J.; Askins, Charles G.; Putnam, Martin A.

    1996-09-01

    We report on civil engineering applications of wavelength multiplexed optical fiber Bragg grating arrays directly produced on the draw tower for testing and surveying advanced structures and materials such as carbon fiber reinforced concrete elements and prestressing cables. We equipped a 6 by 0.9 by 0.5 m concrete beam, which was reinforced with carbon fiber reinforced epoxy laminates, and a 7-m long prestressing carbon fiber cable made of seven twisted strands, with optical fiber Bragg grating sensors. Static strains up to 8000 micrometers/m and dynamic strains up to 1200 micrometers/m were measured with a Michelson interferometer used as Fourier spectrometer with a resolution of about 10 micrometers/m for all sensors. Comparative measurements with electrical resistance strain gauges were in good agreement with the fiber optical results. We installed the fiber sensors in two different arrangements: some Bragg grating array elements measured local strain while others were applied in an extensometric configuration to measure moderate strain over a base length of 0.1 to 1 m.

  15. Thinned fibre Bragg grating as a fuel adulteration sensor: simulation and experimental study

    Science.gov (United States)

    Agarwal, S.; Prajapati, Y. K.; Mishra, V.

    2015-12-01

    This paper presents the implementation of a thinned fibre Bragg grating as a fuel adulteration sensor for volatile organic compounds. The proposed sensor can detect upto 10% adulteration of benzene, toluene and xylene: hydrocarbons precisely, whereas traditional methods can detect only upto 20% adulteration. The results obtained from the experiments are verified using Finite Difference Time Domain method. It is found that experimental results have very less deviation from simulation results. The proposed sensor provides us with the new possibility that may have commercial application, as well.

  16. Embedded Fibre Bragg Grating Sensor Response Model: Crack Growing Detection in Fibre Reinforced Plastic Materials

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    This article presents a novel method to simulate the sensor output response of a Fibre Bragg Grating (FBG) sensor when embedded in a host material (Composite material or adhesive), during a crack growing/damage event. A finite element model of the crack growth mechanisms was developed...... the crack or non-uniform strain, and then identify the presence of such damage in the structure. Experimental tests were conducted in order to validate this concept and support the model. The FBG sensor response model was applied in a delamination of a Wind Turbine trailing edge, to demonstrate...

  17. Fibre Bragg Grating (FBG) sensors as flatness and mechanical stretching sensors

    CERN Document Server

    Benussi, Luigi

    2015-01-01

    Fibre Bragg Grating (FBG) sensors have been so far mainly used in high energy physics as high precision positioning and re-positioning sensor and as low cost, easy to mount and low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide GEM foils of the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS upgrade consists of 144 GEM chambers of about 0.5 $m^{2}$ active area each and based on the triple GEMs technology, to be installed in the very forward region of the CMS endcap. The large active are of each GE1/1 chamber consists of a single GEM foil (the GE1/1 chambers represent the largest GEM foils assembled and operated so far) to be mechanically stretched in order to secure its flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. A network of FBG sensors have been used to determine the optimal m...

  18. Dynamic gate algorithm for multimode fiber Bragg grating sensor systems

    DEFF Research Database (Denmark)

    Ganziy, Denis; Jespersen, O.; Woyessa, Getinet;

    2015-01-01

    -to-noise ratio and different peak shapes. Our simulations and experiments demonstrate that the DGA method is fast and robust with better stability and accuracy than conventional algorithms. This makes it very attractive for future implementation in sensing systems, especially based on multimode fiber Bragg...

  19. Bragg grating rogue wave

    CERN Document Server

    Degasperis, Antonio; Aceves, Alejandro B

    2015-01-01

    We derive the rogue wave solution of the classical massive Thirring model, that describes nonlinear optical pulse propagation in Bragg gratings. Combining electromagnetically induced transparency with Bragg scattering four-wave mixing, may lead to extreme waves at extremely low powers.

  20. Bragg grating rogue wave

    Energy Technology Data Exchange (ETDEWEB)

    Degasperis, Antonio [Dipartimento di Fisica, “Sapienza” Università di Roma, P.le A. Moro 2, 00185 Roma (Italy); Wabnitz, Stefan, E-mail: stefan.wabnitz@unibs.it [Dipartimento di Ingegneria dell' Informazione, Università degli Studi di Brescia and INO-CNR, via Branze 38, 25123 Brescia (Italy); Aceves, Alejandro B. [Southern Methodist University, Dallas (United States)

    2015-06-12

    We derive the rogue wave solution of the classical massive Thirring model, that describes nonlinear optical pulse propagation in Bragg gratings. Combining electromagnetically induced transparency with Bragg scattering four-wave mixing may lead to extreme waves at extremely low powers.

  1. Fiber Bragg Grating Sensor as Valuable Technological Platform for New Generation of Superconducting Magnets

    CERN Document Server

    Chiuchiolo, A; Cusano, A; Bajko, M; Perez, J C; Bajas, H; Viret, P; Giordano, M; Breglio, G

    2014-01-01

    New generation of superconducting magnets for high energy applications designed, manufactured and tested at the European Organization for Nuclear Research (CERN) require the implementation of reliable sensors able to monitor the mechanical stresses affecting the winding from fabrication to operation in magnetic field of 13 T. This work deals with the embedding of Fiber Bragg Grating sensors in a short model Nb3Sn dipole magnet in order to monitor the strain developed in the coil during the cool down to 1.9 K, the powering up to 15.8 kA and the warm up, offering perspectives for the replacement of standard strain gauges.

  2. A novel oil level monitoring sensor based on string tilted fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    JIANG Qi

    2011-01-01

    In this paper, we present a novel oil level monitoring sensor based on string tilted fiber Bragg grating (TFBG). The mea- surement range and sensitivity of oil level monitoring can be modulated via changing the length and number of string tilted fiber gratings. The transmission spectrum of string TFBGs immersed in oil changes obviously with the oil level variation. Experiments are conducted on three 2 crn-length serial TFBGs with the same tilted angle of 10°. A sensitivity of 3.28 dB/cm in the string TFBG sensor is achieved with good linearity by means of TFBG spectrum characteristic with peak-low value. The cladding mode transmission power and the amplitude of high order cladding mode resonance are nearly linear to the oil level variation. This kind of sensor is insensitive to temperature and attributed to be employed in extremely harsh environ- ment oil monitoring.

  3. Fiber Optic Bragg Grating Sensor for Crack Growth Detection of Structures

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Il Bum; Seo, Dae Cheol; Kim, Chi Yeop; Yoon, Dong Jin; Lee, Seung Seok [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2007-08-15

    There are to be some cracks on the material degradation part or the stress concentration parts of the main members, which carry on over-loads, of structures. Because these cracks can be used to evaluate the structural health status, it is important to monitor the crack growth for maintaining the structural safety. In this study, the fiber Bragg grating sensor with a drop ball was developed as a sensor for crack growth detection of an existing crack. The crack growth detection sensor was constructed with three parts: a probe part, a wavelength controlling light source and receiver part, and an impact part. The probe part was just formed with a fiber Bragg grating optical fiber The wavelength controlling light source part was composed of a current supplying circuit, a DFB laser diode, and a TEC controlling circuit for wavelength control. Also, the impact part was just implemented by dropping a steel ball. The performance of this sensor was confirmed by the experiments of the crack detection with an aluminum plate having one existing crack. According to these experiments, the difference of the sensor signal outputs was correlated with the crack length. So, it was confirmed that this sensor could be applied to monitor the crack growth

  4. Using Custom Fiber Bragg Grating-Based Sensors to Monitor Artificial Landslides.

    Science.gov (United States)

    Zhang, Qinghua; Wang, Yuan; Sun, Yangyang; Gao, Lei; Zhang, Zhenglin; Zhang, Wenyuan; Zhao, Pengchong; Yue, Yin

    2016-09-02

    Four custom fiber Bragg grating (FBG)-based sensors are developed to monitor an artificial landslide located in Nanjing, China. The sensors are composed of a rod and two FBGs. Based on the strength of the rods, two sensors are referred to as "hard sensors" (Sensor 1 and Sensor 2), the other two are referred to as "soft sensors" (Sensor 3 and Sensor 4). The two FBGs are fixed on each sensor rod at distances of 50 cm and 100 cm from the top of the rod (an upper FBG and a lower FBG). In the experiment presented in this paper, the sensors are installed on a slope on which an artificial landslide is generated through both machine-based and manual excavation. The fiber sensing system consists of the four custom FBG-based sensors, optical fiber, a static fiber grating demodulation instrument (SM125), and a PC with the necessary software. Experimental data was collected in the presence of an artificial landslide, and the results show that the lower FBGs are more sensitive than the upper FBGs for all four of the custom sensors. It was also found that Sensor 2 and Sensor 4 are more capable of monitoring small-scale landslides than Sensor 1 and Sensor 3, and this is mainly due to their placement location with respect to the landslide. The stronger rods used in the hard sensors make them more adaptable to the harsh environments of large landslides. Thus, hard sensors should be fixed near the landslide, while soft sensors should be placed farther away from the landslide. In addition, a clear tendency of strain variation can be detected by the soft sensors, which can be used to predict landslides and raise a hazard alarm.

  5. Sensitivity of contact-free fiber Bragg grating sensor to ultrasonic Lamb wave

    Science.gov (United States)

    Wee, Junghyun; Hackney, Drew; Peters, Kara; Wells, Brian; Bradford, Philip

    2016-04-01

    Networks of fiber Bragg grating (FBG) sensors can serve as structural health monitoring (SHM) systems for large-scale structures based on the collection of ultrasonic waves. The demodulation of structural Lamb waves requires a high signal-to-noise ratio because Lamb waves have a low amplitude. This paper investigates the signal transfer between Lamb waves propagating in an aluminum plate collected by an optical fiber containing a FBG. The fiber is bonded to the plate at locations away from the FBG. The Lamb waves are converted into longitudinal and flexural traveling waves propagating along the optical fiber, which are then transmitted to the Bragg grating. The signal wave amplitude is measured for different distances between the bond location and the Bragg grating. Bonding the optical fiber away from the FBG location and closer to the signal source produces a significant increase in signal amplitude, here measured to be 5.1 times that of bonding the Bragg grating itself. The arrival time of the different measured wave coupling paths are also calculated theoretically, verifying the source of the measured signals. The effect of the bond length to Lamb wavelength ratio is investigated, showing a peak response as the bond length is reduced compared to the wavelength. This study demonstrates that coupling Lamb waves into guided traveling waves in an optical fiber away from the FBG increases the signal-to-noise ratio of Lamb wave detection, as compared to direct transfer of the Lamb wave to the optical fiber at the location of the FBG.

  6. Fiber optic hydrogen sensor based on an etched Bragg grating coated with palladium.

    Science.gov (United States)

    Coelho, L; de Almeida, J M M M; Santos, J L; Viegas, D

    2015-12-10

    A study of a sensor for hydrogen (H2) detection based on fiber Bragg gratings coated with palladium (Pd) with self-temperature compensation is presented. The cladding around the gratings was reduced down to 50 μm diameter by a chemical etching process. One of the gratings was left uncoated, and the other was coated with 150 nm of Pd. It was observed that palladium hydride has unstable behavior in environments with high humidity level. A simple solution to overcome this problem based on a Teflon tape is presented. The sensing device studied was able to respond to H2 concentrations in the range 0%-1% v/v at room temperature and atmospheric pressure, achieving sensitivities larger than 20 pm/% v/v. Considering H2 concentrations in nitrogen up to 1%, the performance of the sensing head was characterized for different thicknesses of Pd coating ranging from 50 to 200 nm. PMID:26836856

  7. Fiber optic relative humidity sensor based on the tilted fiber Bragg grating coated with graphene oxide

    Science.gov (United States)

    Wang, Youqing; Shen, Changyu; Lou, Weimin; Shentu, Fengying; Zhong, Chuan; Dong, Xinyong; Tong, Limin

    2016-07-01

    A fiber optic relative humidity (RH) sensor based on the tilted fiber Bragg grating (TFBG) coated with graphene oxide (GO) film was presented. Amplitudes of the cladding mode resonances of the TFGB varies with the water sorption and desorption processes of the GO film, because of the strong interactions between the excited backward propagating cladding modes and the GO film. By detecting the transmission intensity changes of the cladding mode resonant dips at the wavelength of 1557 nm, the maximum sensitivity of 0.129 dB/%RH with a linear correlation coefficient of 99% under the RH range of 10-80% was obtained. The Bragg mode of TFBG can be used as power or wavelength references, since it is inherently insensitive to RH changes. In addition, the proposed humidity sensor shows a good performance in repeatability and stability.

  8. Dental composite resins: measuring the polymerization shrinkage using optical fiber Bragg grating sensors

    Science.gov (United States)

    Ottevaere, H.; Tabak, M.; Chah, K.; Mégret, P.; Thienpont, H.

    2012-04-01

    Polymerization shrinkage of dental composite materials is recognized as one of the main reasons for the development of marginal leakage between a tooth and filling material. As an alternative to conventional measurement methods, we propose optical fiber Bragg grating (FBG) based sensors to perform real-time strain and shrinkage measurements during the curing process of dental resin cements. We introduce a fully automated set-up to measure the Bragg wavelength shift of the FBG strain sensors and to accurately monitor the linear strain and shrinkage of dental resins during curing. Three different dental resin materials were studied in this work: matrix-filled BisGMA-based resins, glass ionomers and organic modified ceramics.

  9. Stress-transfer characteristics of embedded fiber Bragg grating sensors

    Institute of Scientific and Technical Information of China (English)

    BAO Ji-long; CHEN Ying; ZHAO Hong-xia

    2005-01-01

    The shear lag theory is used to analyze the stress transfer from concrete matrix to FBG sensors based on that the FBG sensor and the concrete matrix are composite. The stress transfer formula and the coefficient are obtained. The experiments prove that the theoretical results of the stress transfer by the stress transfer formula are in well agreement with the experimental data.

  10. Using Custom Fiber Bragg Grating-Based Sensors to Monitor Artificial Landslides

    Science.gov (United States)

    Zhang, Qinghua; Wang, Yuan; Sun, Yangyang; Gao, Lei; Zhang, Zhenglin; Zhang, Wenyuan; Zhao, Pengchong; Yue, Yin

    2016-01-01

    Four custom fiber Bragg grating (FBG)-based sensors are developed to monitor an artificial landslide located in Nanjing, China. The sensors are composed of a rod and two FBGs. Based on the strength of the rods, two sensors are referred to as “hard sensors” (Sensor 1 and Sensor 2), the other two are referred to as “soft sensors” (Sensor 3 and Sensor 4). The two FBGs are fixed on each sensor rod at distances of 50 cm and 100 cm from the top of the rod (an upper FBG and a lower FBG). In the experiment presented in this paper, the sensors are installed on a slope on which an artificial landslide is generated through both machine-based and manual excavation. The fiber sensing system consists of the four custom FBG-based sensors, optical fiber, a static fiber grating demodulation instrument (SM125), and a PC with the necessary software. Experimental data was collected in the presence of an artificial landslide, and the results show that the lower FBGs are more sensitive than the upper FBGs for all four of the custom sensors. It was also found that Sensor 2 and Sensor 4 are more capable of monitoring small-scale landslides than Sensor 1 and Sensor 3, and this is mainly due to their placement location with respect to the landslide. The stronger rods used in the hard sensors make them more adaptable to the harsh environments of large landslides. Thus, hard sensors should be fixed near the landslide, while soft sensors should be placed farther away from the landslide. In addition, a clear tendency of strain variation can be detected by the soft sensors, which can be used to predict landslides and raise a hazard alarm. PMID:27598163

  11. Advanced Interrogation of Fiber-Optic Bragg Grating and Fabry-Perot Sensors with KLT Analysis

    Directory of Open Access Journals (Sweden)

    Daniele Tosi

    2015-10-01

    Full Text Available The Karhunen-Loeve Transform (KLT is applied to accurate detection of optical fiber sensors in the spectral domain. By processing an optical spectrum, although coarsely sampled, through the KLT, and subsequently processing the obtained eigenvalues, it is possible to decode a plurality of optical sensor results. The KLT returns higher accuracy than other demodulation techniques, despite coarse sampling, and exhibits higher resilience to noise. Three case studies of KLT-based processing are presented, representing most of the current challenges in optical fiber sensing: (1 demodulation of individual sensors, such as Fiber Bragg Gratings (FBGs and Fabry-Perot Interferometers (FPIs; (2 demodulation of dual (FBG/FPI sensors; (3 application of reverse KLT to isolate different sensors operating on the same spectrum. A simulative outline is provided to demonstrate the KLT operation and estimate performance; a brief experimental section is also provided to validate accurate FBG and FPI decoding.

  12. Advanced Interrogation of Fiber-Optic Bragg Grating and Fabry-Perot Sensors with KLT Analysis.

    Science.gov (United States)

    Tosi, Daniele

    2015-10-29

    The Karhunen-Loeve Transform (KLT) is applied to accurate detection of optical fiber sensors in the spectral domain. By processing an optical spectrum, although coarsely sampled, through the KLT, and subsequently processing the obtained eigenvalues, it is possible to decode a plurality of optical sensor results. The KLT returns higher accuracy than other demodulation techniques, despite coarse sampling, and exhibits higher resilience to noise. Three case studies of KLT-based processing are presented, representing most of the current challenges in optical fiber sensing: (1) demodulation of individual sensors, such as Fiber Bragg Gratings (FBGs) and Fabry-Perot Interferometers (FPIs); (2) demodulation of dual (FBG/FPI) sensors; (3) application of reverse KLT to isolate different sensors operating on the same spectrum. A simulative outline is provided to demonstrate the KLT operation and estimate performance; a brief experimental section is also provided to validate accurate FBG and FPI decoding.

  13. Crack Growth Monitoring by Embedded Optical Fibre Bragg Grating Sensors: Fibre Reinforced Plastic Crack Growing Detection

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    caused by the crack, and to correlate with the FBG sensor. A Material-Sensor model was developed in order to predict the sensor output response under a crack/delamination situation, which can be used as an analysis tool for future application of this measurement technology in more complex structures.......This article presents a novel method to asses a crack growing/damage event in fibre reinforced plastic, or adhesive using Fibre Bragg Grating (FBG) sensors embedded in a host material. Different features of the crack mechanism that induce a change in the FBG response were identified. Double...... Cantilever Beams specimens made with glass fibre glued with structural adhesive, were instrumented with an array of FBG sensors embedded in the material and tested using an experimental fracture procedure. A digital image correlation technique was used to determine the presence of the specific phenomena...

  14. Coating based Fiber Bragg Grating humidity sensor array

    NARCIS (Netherlands)

    Cheng, L.K.; Boersma, A.; Jansen, T.H.

    2012-01-01

    A coating based FBG humidity sensor is developed for distributed humidity sensing. The sensitivity of the coated FBG is optimized by varying the chemical composition and the thickness of the coating. A sensitivity of ~2 pm/%RH and a rapid response are demonstrated. The composition of the coating can

  15. Estimating needle-tissue interaction forces for hollow needles using fiber Bragg grating sensors

    Science.gov (United States)

    Kumar, Saurabh; Shrikanth, V.; Bharadwaj, Amrutur; Asokan, Sundarrajan; Bobji, M. S.

    2016-03-01

    Brachytherapy and neurological procedures can benefit from real-time estimation of needle-tissue interaction forces, specifically for robotic or robot-assisted procedures. Fiber Bragg Grating Sensors provide advantages of very small size and electromagnetic immunity for use in measurement of the forces directly at the needle tip. This has advantages compared to measurements at the needle shaft which require extensive models of the friction between needle and tissues with varying depth. This paper presents the measurement of tip forces for a hollow needle and compensation for bending when encountering regions of varying stiffness in phantoms with multiple layers prepared using Polydimethylsiloxane.

  16. Remote fiber optic switch powered by light for robust interrogation of fiber Bragg grating sensor networks

    International Nuclear Information System (INIS)

    In this work, a remote fiber optic switch powered by light is demonstrated experimentally. This fiber optic switch is powered by a photovoltaic power converter illuminated by a Raman laser. The switch can operate at distances up to 100 km. This switch is used to develop a remote resilient fiber Bragg grating (FBG) multiplexing network interrogated by a commercial FBG interrogator. In the proposed set-up the switch selects the branch of the FBG network located 50 km away from the interrogation unit in order to enable a two-way interrogation path for each sensor to prevent connection failures or fiber breakages. (paper)

  17. Shear stress sensing with Bragg grating-based sensors in microstructured optical fibers.

    Science.gov (United States)

    Sulejmani, Sanne; Sonnenfeld, Camille; Geernaert, Thomas; Luyckx, Geert; Van Hemelrijck, Danny; Mergo, Pawel; Urbanczyk, Waclaw; Chah, Karima; Caucheteur, Christophe; Mégret, Patrice; Thienpont, Hugo; Berghmans, Francis

    2013-08-26

    We demonstrate shear stress sensing with a Bragg grating-based microstructured optical fiber sensor embedded in a single lap adhesive joint. We achieved an unprecedented shear stress sensitivity of 59.8 pm/MPa when the joint is loaded in tension. This corresponds to a shear strain sensitivity of 0.01 pm/µε. We verified these results with 2D and 3D finite element modeling. A comparative FEM study with conventional highly birefringent side-hole and bow-tie fibers shows that our dedicated fiber design yields a fourfold sensitivity improvement. PMID:24105585

  18. Quasi-distributed fiber Bragg grating temperature sensors for stator bars monitoring of large electric generators

    Science.gov (United States)

    Dreyer, Uilian J.; da Silva, Erlon V.; Biffe Di Renzo, André; Martelli, Cicero; Cardozo da Silva, Jean Carlos

    2016-05-01

    This work presents the application of a sensor based on quasi-distributed Fiber Bragg Gratings to monitor stator bars temperature of large electric generators. The applied FBG packaging method follows industrial standard procedures, and resulted in a robust and reliable sensing method, facilitating the future installation in the power plant. Experimental results are acquired in laboratory using the expected range of temperature values in the real machine. The measurement errors in the recorded results are within the calculated uncertainties and the time constant is shorter than what is obtained with conventional RTD for the same application.

  19. Strain transfer of surface-bonded fiber Bragg grating sensors for airship envelope structural health monitoring

    Institute of Scientific and Technical Information of China (English)

    Hai-tao ZHAO; Quan-bao WANG; Ye QIU; Ji-an CHEN; Yue-ying WANG; Zhen-min FAN

    2012-01-01

    This paper deals with an improved bonding approach ofsurface-bonded fiber Bragg grating (FBG) sensors for airship envelope structural health monitoring (SHM) under the strain transfer theory.A theoretical formula is derived from the proposed model to predict the strain transfer relationship between the airship envelope and fiber core.Then theoretical predictions are validated by numerical analysis using the finite element method (FEM).Finally,on the basis of the theoretical approach and numerical validation,parameters that influence the strain transfer rate from the airship envelope to fiber core and the ratio of effective sensing length are analyzed,and some meaningful conclusions are provided.

  20. Fiber Bragg Grating sensors for deformation monitoring of GEM foils in HEP detectors

    CERN Document Server

    Benussi, L; Caponero, M; Muhammad, S; Passamonti, L; Piccolo, D; Pierluigi, D; Raffone, G; Russo, A; Saviano, G

    2015-01-01

    Fiber Bragg Grating (FBG) sensors have been so far mainly used in high energy physics (HEP) as high precision positioning and re-positioning sensors and as low cost, easy to mount, radiation hard and low space- consuming temperature and humidity devices. FBGs are also commonly used for very precise strain measurements. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide Gas Electron Multiplier (GEM) foils of the GE1/1 chambers of the Compact Muon Solenoid (CMS) experiment at Large Hadron Collider (LHC) of CERN. A network of FBG sensors has been used to determine the optimal mechanical tension applied and to characterize the mechanical stress applied to the foils. The preliminary results of the test performed on a full size GE1/1 final prototype and possible future developments will be discussed.

  1. Crack growth monitoring in composite materials using embedded optical Fiber Bragg Grating sensor

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    In this paper a novel method to assess a crack growing/damage event in fiber reinforced plastic, or adhesive using Fiber Bragg Grating (FBG) sensors embedded in a host material is shown. Different features of the crack mechanism that induce a change in the FBG response were identified. Double...... Cantilever Beams specimens made with glass fibre glued with structural adhesive, were instrumented with an array of FBG sensors embedded in the material and tested using an experimental fracture procedure. A digital image correlation technique was used to determine the presence of the specific phenomena...... caused by the crack, and to correlate with the FBG sensor. An algorithm was developed that analyses the reflected peak at each measurement time, and calculates the contribution of each fracture phenomenon to the change in the FBG response. This Material-Sensor model was implemented in a Finite Element...

  2. Sensitivity Distribution Properties of a Phase-Shifted Fiber Bragg Grating Sensor to Ultrasonic Waves

    Directory of Open Access Journals (Sweden)

    Qi Wu

    2014-01-01

    Full Text Available In this research, the sensitivity distribution properties of a phase-shifted fiber Bragg grating (PS-FBG to ultrasonic waves were investigated employing the surface attachment method. A careful consideration was taken and examined by experimental results to explain that the distances and angles between the sensor and ultrasonic source influence not only the amplitudes, but also the initial phases, waveforms, and spectra of detected signals. Furthermore, factors, including the attachment method and the material’s geometric dimensions, were also discussed. Although these results were obtained based on PS-FBG, they are also applicable to a normal FBG sensor or even an optical fiber sensor, due to the identical physical changes induced by ultrasonic waves in all three. Thus, these results are useful for applications of optical fiber sensors in non-destructive testing and structural health monitoring.

  3. A Fiber Bragg Grating Temperature Sensor for 2-400 K

    Energy Technology Data Exchange (ETDEWEB)

    Zaynetdinov, Madrakhim; See, Erich M.; Geist, Brian; Ciovati, Gianluigi; Robinson, Hans D.; Kochergin, Vladimir

    2015-03-01

    We demonstrate fiber optic, multiplexible temperature sensing using a fiber Bragg grating (FBG) with an operational range of 2-400 K, and a temperature resolution better than 10 mK for temperatures < 12 K. This represents a significant reduction in the lowest usable temperature as well as a significant increase in sensitivity at cryogenic temperatures compared with previously reported multiplexible solutions. This is accomplished by mounting the section of the fiber with a FBG on a polytetrafluoroethylene coupon, which has a non-negligible coefficient of thermal expansion down to < 4 K. The sensors exhibit a good stability over multiple temperature cycles and acceptable sensor-to-sensor repeatability. Possible applications for this sensor include distributed temperature sensing across superconducting elements and cryogenic temperature measurements in environments where electrical measurements are impractical or unsafe.

  4. Fiber Bragg grating dynamic strain sensor using an adaptive reflective semiconductor optical amplifier source.

    Science.gov (United States)

    Wei, Heming; Tao, Chuanyi; Zhu, Yinian; Krishnaswamy, Sridhar

    2016-04-01

    In this paper, a reflective semiconductor optical amplifier (RSOA) is configured to demodulate dynamic spectral shifts of a fiber Bragg grating (FBG) dynamic strain sensor. The FBG sensor and the RSOA source form an adaptive fiber cavity laser. As the reflective spectrum of the FBG sensor changes due to dynamic strains, the wavelength of the laser output shifts accordingly, which is subsequently converted into a corresponding phase shift and demodulated by an unbalanced Michelson interferometer. Due to the short transition time of the RSOA, the RSOA-FBG cavity can respond to dynamic strains at high frequencies extending to megahertz. A demodulator using a PID controller is used to compensate for low-frequency drifts induced by temperature and large quasi-static strains. As the sensitivity of the demodulator is a function of the optical path difference and the FBG spectral width, optimal parameters to obtain high sensitivity are presented. Multiplexing to demodulate multiple FBG sensors is also discussed. PMID:27139682

  5. Sensitivity improvement of a fibre Bragg grating pH sensor with elastomeric coating

    International Nuclear Information System (INIS)

    A new optical pH sensor based on fibre Bragg grating (FBG) is demonstrated. The sensor consists of a FBG coated with pH sensitive hydrogel. The sensing was performed through the detection of wavelength shifts resulting from the induced strain on the FBG due to mechanical expansion of the hydrogel. An elastomeric coating was applied before the hydrogel coating to improve the sensitivity. The sensor performance was investigated by simulating the hydrogel swelling and the strain induced on the FBG. The swelling of hydrogel due to pH change was modelled using a free-energy function and was solved using the finite element method. With silicone rubber as the elastomer material, the results show that the sensitivity was improved by up to 66% compared to that of the FBG pH sensor without elastomeric coating

  6. Flat-Cladding Fiber Bragg Grating Sensors for Large Strain Amplitude Fatigue Tests

    Directory of Open Access Journals (Sweden)

    Xijia Gu

    2010-08-01

    Full Text Available We have successfully developed a flat-cladding fiber Bragg grating sensor for large cyclic strain amplitude tests of up to ±8,000 με. The increased contact area between the flat-cladding fiber and substrate, together with the application of a new bonding process, has significantly increased the bonding strength. In the push-pull fatigue tests of an aluminum alloy, the plastic strain amplitudes measured by three optical fiber sensors differ only by 0.43% at a cyclic strain amplitude of ±7,000 με and 1.9% at a cyclic strain amplitude of ±8,000 με. We also applied the sensor on an extruded magnesium alloy for evaluating the peculiar asymmetric hysteresis loops. The results obtained were in good agreement with those measured from the extensometer, a further validation of the sensor.

  7. Review of the Strain Modulation Methods Used in Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Kuo Li

    2016-01-01

    Full Text Available Fiber Bragg grating (FBG is inherently sensitive to temperature and strain. By modulating FBG’s strain, various FBG sensors have been developed, such as sensors with enhanced or reduced temperature sensitivity, strain/displacement sensors, inclinometers, accelerometers, pressure meters, and magnetic field meters. This paper reviews the strain modulation methods used in these FBG sensors and categorizes them according to whether the strain of an FBG is changed evenly. Then, those even-strain-change methods are subcategorized into (1 attaching/embedding an FBG throughout to a base and (2 fixing the two ends of an FBG and (2.1 changing the distance between the two ends or (2.2 bending the FBG by applying a transverse force at the middle of the FBG. This review shows that the methods of “fixing the two ends” are prominent because of the advantages of large tunability and frequency modulation.

  8. Multi-channel monolithic integrated optic fiber Bragg grating sensor interrogator

    Science.gov (United States)

    Mendoza, Edgar A.; Esterkin, Yan; Kempen, Cornelia; Sun, Zongjian

    2011-09-01

    Fiber Bragg grating (FBG) is a mature sensing technology for the measurement of strain, vibration, acoustics, acceleration, pressure, temperature, moisture, and corrosion. It has gained rapid acceptance in civil, aerospace, chemical and petrochemical, medicine, aviation and automotive industries. The most prominent advantages of FBG are: small size and light weight, distributed array of FBG transducers on a single fiber, and immunity to radio frequency interference. However, a major disadvantage of FBG technology is that conventional state-of-the-art FBG interrogation system is typically bulky, heavy, and costly bench top instruments that are typically assembled from off-the-shelf fiber optic and optical components integrated with a signal electronics board into an instrument console. Based on the industrial need for a compact FBG interrogation system, this paper describes recent progress towards the development of miniature fiber Bragg grating sensor interrogator (FBG-Transceiver™) system based on multi-channel monolithic integrated optic sensor microchip technology. The integrated optic microchip technology enables monolithic integration of all functionalities, both passive and active, of conventional bench top FBG sensor interrogator system, packaged in a miniaturized, low power operation, 2 cm×5 cm small form factor (SFF) package suitable for long-term structural health monitoring in applications where size, weight, and power are critical for operation.

  9. Fibre Bragg Grating Sensor Signal Post-processing Algorithm: Crack Growth Monitoring in Fibre Reinforced Plastic Structures

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2016-01-01

    A novel method to assess a crack growing/damage event in fibre reinforced plastic, using conventional single mode Fibre Bragg Grating sensors embedded in the host material is presented in this article. Three different damage mechanisms that can change the sensor output, longitudinal strain exx...... in three different loading conditions, where were obtained very promising results that enable crack growth monitoring...

  10. Fiber Bragg distributed chemical sensor

    NARCIS (Netherlands)

    Boersma, A.; Cheng, L.K.; Jansen, T.H.

    2010-01-01

    A distributed chemical sensor is developed by coating multiple Bragg gratings in a fibre with chemical selective responsive coatings. The optical response of the coated grating is optimised and the recoat process is very reproducible.

  11. Fiber Bragg Grating Sensor for Fault Detection in Radial and Network Transmission Lines

    Science.gov (United States)

    Moghadas, Amin A.; Shadaram, Mehdi

    2010-01-01

    In this paper, a fiber optic based sensor capable of fault detection in both radial and network overhead transmission power line systems is investigated. Bragg wavelength shift is used to measure the fault current and detect fault in power systems. Magnetic fields generated by currents in the overhead transmission lines cause a strain in magnetostrictive material which is then detected by Fiber Bragg Grating (FBG). The Fiber Bragg interrogator senses the reflected FBG signals, and the Bragg wavelength shift is calculated and the signals are processed. A broadband light source in the control room scans the shift in the reflected signal. Any surge in the magnetic field relates to an increased fault current at a certain location. Also, fault location can be precisely defined with an artificial neural network (ANN) algorithm. This algorithm can be easily coordinated with other protective devices. It is shown that the faults in the overhead transmission line cause a detectable wavelength shift on the reflected signal of FBG and can be used to detect and classify different kind of faults. The proposed method has been extensively tested by simulation and results confirm that the proposed scheme is able to detect different kinds of fault in both radial and network system. PMID:22163416

  12. Fiber Bragg Grating Sensor for Fault Detection in Radial and Network Transmission Lines

    Directory of Open Access Journals (Sweden)

    Mehdi Shadaram

    2010-10-01

    Full Text Available In this paper, a fiber optic based sensor capable of fault detection in both radial and network overhead transmission power line systems is investigated. Bragg wavelength shift is used to measure the fault current and detect fault in power systems. Magnetic fields generated by currents in the overhead transmission lines cause a strain in magnetostrictive material which is then detected by Fiber Bragg Grating (FBG. The Fiber Bragg interrogator senses the reflected FBG signals, and the Bragg wavelength shift is calculated and the signals are processed. A broadband light source in the control room scans the shift in the reflected signal. Any surge in the magnetic field relates to an increased fault current at a certain location. Also, fault location can be precisely defined with an artificial neural network (ANN algorithm. This algorithm can be easily coordinated with other protective devices. It is shown that the faults in the overhead transmission line cause a detectable wavelength shift on the reflected signal of FBG and can be used to detect and classify different kind of faults. The proposed method has been extensively tested by simulation and results confirm that the proposed scheme is able to detect different kinds of fault in both radial and network system.

  13. Post-Impact Fatigue Damage Monitoring Using Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Chow-Shing Shin

    2014-03-01

    Full Text Available It has been shown that impact damage to composite materials can be revealed by embedded Fiber Bragg Gratings (FBG as a broadening and splitting of the latter’s characteristic narrow peak reflected spectrum. The current work further subjected the impact damaged composite to cyclic loading and found that the FBG spectrum gradually submerged into a rise of background intensity as internal damages progressed. By skipping the impact, directing the impact to positions away from the FBG and examining the extracted fibers, we concluded that the above change is not a result of deterioration/damage of the sensor. It is caused solely by the damages initiated in the composite by the impact and aggravated by fatigue loading. Evolution of the grating spectrum may therefore be used to monitor qualitatively the development of the incurred damages.

  14. Digital monitoring for heavy duty mechanical equipment based on fiber Bragg grating sensor

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The digital monitoring principle and technologies for heavy duty mechanical equipment based on fiber Bragg grating (FBG) technology are introduced in this paper. The fundamentals of new-style FBG sensing technology, including the photorefractive effect of FBG, the physical formation, and the relation between optical properties and grating parameters, are investigated. The plaster, encapsulation and distribution planning of FBG sensor (FBGS), which is used to monitor heavy duty mechanical equipment under abominable environment and extreme conditions, are also studied. In addition, theoretical and experimental researches on the strain, temperature, displacement, and stress transmission characteristics between FBGS and detection interface are presented. The principle and method for temperature compensation in non-uniformity temperature field are described in detail as well. Comparing with the traditional sensing monitoring techniques, the application of FBGS technology on digital monitoring and diagnosis for heavy duty mechanical equipment has a number of significant technical advantages and will make a new breakthrough in this field.

  15. Optical fiber laser sensor with a cavity of 8.6 Km formed by two fiber Bragg gratings used as mirrors

    CERN Document Server

    May, M; Vázquez, R A; Basurto, M A; Shlyagin, M G; Márquez, I

    2002-01-01

    We report the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980 nm, an 8.67 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength is strained which can be used as a sensor element. The laser generation thus shows that the Bragg grating is under strain. Furthermore, our configuration give us the possibility for knowing the distance between two Bragg gratings when the laser beating frequency is measured. A measurement precision better than 25 m in 8.67 Km is shown to be feasible. (Author)

  16. Fiber Bragg Grating Array as a Quasi Distributed Temperature Sensor for Furnace Boiler Applications

    Science.gov (United States)

    Reddy, P. Saidi; Prasad, R. L. N. Sai; Sengupta, D.; Shankar, M. Sai; Srimannarayana, K.; Kishore, P.; Rao, P. Vengal

    2011-10-01

    This paper presents the experimental work on distributed temperature sensing making use of Fiber Bragg grating (FBG) array sensor for possible applications in the monitoring of temperature profile in high temperature boilers. A special sensor has been designed for this purpose which consists of four FBGs (of wavelengths λB1 = 1547.28 nm, λB2 = 1555.72 nm, λB3 = 1550.84 nm, λB4 = 1545.92 nm) written in hydrogen loaded fiber in line with a spacing of 15 cm between them. All the FBGs are encapsulated inside a stainless steel tube for avoiding micro cracks using rigid probe technique. The spatial distribution of temperature profile inside a prototype boiler has been measured experimentally both in horizontal and vertical directions employing the above sensor and the results are presented.

  17. Fiber Bragg grating laser sensor with direct radio-frequency readout.

    Science.gov (United States)

    Malara, P; Campanella, C E; Giorgini, A; Avino, S; Gagliardi, G

    2016-04-01

    A fiber Bragg grating (FBG)-coupled ring laser sensor is demonstrated. In the proposed configuration the interrogating source, the sensing head and the readout instrument are integrated in a single fiber-optic device. An FBG inserted within a bidirectional fiber ring couples the two counterpropagating modes of the cavity, generating a splitting of the resonant wavelengths proportional to the FBG reflectivity. When the cavity gain is brought beyond threshold, the two peaks of the split resonances simultaneously lase, leading to a beat note in the emission spectrum whose frequency tracks any small shift of the FBG reflectivity spectrum. Such a beat note can be simply monitored by a frequency counter, without the need for an optical spectrometer, allowing to significantly reduce size and costs of the sensor setup. The sensing performance compares well to the state-of-the-art thermo-mechanical fiber sensors. PMID:27192251

  18. Strain fiber sensor based on beat frequency with chirped fiber Bragg grating

    Science.gov (United States)

    Wang, Xu; Zhang, Haojie; Wen, Quan; Chen, Longfei; Wang, Fang; Liu, Yufang; Yu, Kun

    2016-07-01

    We propose a strain fiber sensor that is interrogated via longitudinal mode beat frequency with a linear chirped fiber Bragg grating (CFBG). Unlike conventional sensors, in the proposed sensor, the CFBG is used to convert wavelength changes into resonant cavity length changes. Further, the beat frequency stability of the fiber laser is fully utilized to significantly improve measurement accuracy. Consequently, because cavity changes account for 5.1% of the total cavity length, the measurement accuracy can be as large as 7.06×10-7 ɛ-i.e., approximately five times greater than the accuracy obtained by stretching the resonant cavity fiber. The maximum experimental strain error range is ±14.5 μɛ.

  19. Field tests of Fibre Bragg Grating sensors incorporated into CFRP for Railway Bridge strengthening condition monitoring

    DEFF Research Database (Denmark)

    Täljsten, Björn; Kerrouche, Abdelfathe; Leighton, J;

    2008-01-01

    This paper reports results obtained from an unusual situation in structural monitoring – a ‘test-to-destruction’, measuring strain using a series of fibre Bragg gratings (FBG) sensors on a decommissioned concrete Railway Bridge in Örnsköldsvik, Sweden. The study formed part of the FP6 EU funded...... the study, the FBG sensors were continuously monitored, allowing the incremental increases in the strain to be seen and through the yield point of the carbon composite reinforcement. The sensors were able to follow the resulting induced changes in strain of over a range in excess of 4000µε. The measurements...... reinforcements used in remedial repair and for monitoring better the performance of existing bridge structures....

  20. Temperature-Insensitive Chemical Sensor with Twin Bragg Gratings in an Optical Fibre

    Institute of Scientific and Technical Information of China (English)

    SANG Xin-Zhu; YU Chong-Xiu; YAN Bin-Bin; MA Jian-Xin; MENG Zhao-Fang; Mayteevarunyoo T.; LU Nai-Guang

    2006-01-01

    To reduce temperature sensitivity of the fibre Bragg grating (FBG) chemical sensor, a simple method is proposed by measuring the peak wavelength difference between an etched FBG and an un-etched one in an optical fibre.Thermal characteristics and chemical sensitivity of the sensor are experimentally investigated. The experimental results indicate that the etched FBG and the rest one have almost the same thermal response, and concentration changes of the surrounding chemical solutions can be detected by measuring the peak wavelength difference between them. The sensor has been used to measure the concentrations of propylene glycol solutions and sugar solutions, and it could detect 0.7% and 0.45% concentration changes for them with an optical spectrum analyser in resolution of 10pm.

  1. Compact bending sensor based on a fiber Bragg grating in an abrupt biconical taper.

    Science.gov (United States)

    Cui, Wei; Si, Jinhai; Chen, Tao; Hou, Xun

    2015-05-01

    We propose and experimentally demonstrate a compact bending sensor. The head of the sensor is only 0.8 mm in length, and consists of an abrupt biconical fiber taper formed using a conventional fusion splicer, in which a fiber Bragg grating (FBG) is inscribed using a femtosecond laser. The biconical taper incorporating the FBG can couple light from the cladding to the backward-propagating core mode, which realizes an interferometer in reflection-mode. Bending of the structure can be detected from the contrast change of interference fringes. A configuration to measure curvature is investigated to demonstrate the sensing characteristics. The temperature cross-sensitivity of the sensor is studied, and the results demonstrate that it is insensitive to temperature. PMID:25969198

  2. A minimally invasive in-fiber Bragg grating sensor for intervertebral disc pressure measurements

    International Nuclear Information System (INIS)

    We present an in-fiber Bragg grating (FBG) based intervertebral disc (IVD) pressure sensor that has pressure sensitivity seven times greater than that of a bare fiber, and a major diameter and sensing area of only 400 µm and 0.03 mm2, respectively. This is the only optical, the smallest and the most mechanically compliant disc pressure sensor reported in the literature. This is also an improvement over other FBG pressure sensors that achieve increased sensitivity through mechanical amplification schemes, usually resulting in major diameters and sensing lengths of many millimeters. Sensor sensitivity is predicted using numerical models, and the predicted sensitivity is verified through experimental calibrations. The sensor is validated by conducting IVD pressure measurements in porcine discs and comparing the FBG measurements to those obtained using the current standard sensor for IVD pressure. The predicted sensitivity of the FBG sensor matched with that measured experimentally. IVD pressure measurements showed excellent repeatability and agreement with those obtained from the standard sensor. Unlike the current larger sensors, the FBG sensor could be used in discs with small disc height (i.e. cervical or degenerated discs). Therefore, there is potential to conduct new measurements that could lead to new understanding of the biomechanics

  3. High Neutron Fluence Survivability Testing of Advanced Fiber Bragg Grating Sensors

    International Nuclear Information System (INIS)

    The motivation for the reported research was to support NASA space nuclear power initiatives through the development of advanced fiber optic sensors for space-based nuclear power applications. The purpose of the high-neutron fluence testing was to demonstrate the survivability of fiber Bragg grating (FBG) sensors in a fission reactor environment. 520 FBGs were installed in the Ford reactor at the University of Michigan. The reactor was operated for 1012 effective full power hours resulting in a maximum neutron fluence of approximately 5x1019 n/cm2, and a maximum gamma dose of 2x103 MGy gamma. This work is significant in that, to the knowledge of the authors, the exposure levels obtained are approximately 1000 times higher than for any previously published experiment. Four different fiber compositions were evaluated. An 87% survival rate was observed for fiber Bragg gratings located at the fuel centerline. Optical Frequency Domain Reflectometry (OFDR), originally developed at the NASA Langley Research Center, can be used to interrogate several thousand low-reflectivity FBG strain and/or temperature sensors along a single optical fiber. A key advantage of the OFDR sensor technology for space nuclear power is the extremely low mass of the sensor, which consists of only a silica fiber 125μm in diameter. The sensors produced using this technology will fill applications in nuclear power for current reactor plants, emerging Generation-IV reactors, and for space nuclear power. The reported research was conducted by Luna Innovations and was funded through a Small Business Innovative Research (SBIR) contract with the NASA Glenn Research Center

  4. Fiber Bragg Grating Based Thermometry

    OpenAIRE

    Ahmed, Zeeshan; Filla, James; Guthrie, William; Quintavalle, John

    2016-01-01

    In recent years there has been considerable interest in developing photonic temperature sensors such as the Fiber Bragg gratings (FBG) as an alternative to resistance thermometry. In this study we examine the thermal response of FBGs over the temperature range of 233 K to 393 K. We demonstrate, in a hermetically sealed dry Argon environment, that FBG devices show a quadratic dependence on temperature with expanded uncertainties (k = 2) of ~500 mK. Our measurements indicate that the combined m...

  5. Dynamic assessment of women pelvic floor function by using a fiber Bragg grating sensor system

    Science.gov (United States)

    Ferreira, Luis A.; Araújo, Francisco M.; Mascarenhas, Teresa; Natal Jorge, Renato M.; Fernandes, António A.

    2006-02-01

    We present a novel sensing system consisting of an intravaginal probe and an optoelectronic measurement unit, which allows an easy, comfortable and quantitative dynamic evaluation of women pelvic floor muscle strength. The sensing probe is based on a silicone cylinder that transduces radial muscle pressure into axial load applied to a fiber Bragg grating strain sensor. The performance of a first sensor probe prototype with temperature referentiation and of the autonomous, portable optoelectronic measurement unit with data logging capabilities and graphical user interface is disclosed. The presented results refer to an ongoing collaboration work between researchers from the Medical, Optoelectronics and Mechanical areas, directed to the development of equipment that can assist in medical practice and help in the research of primary mechanisms responsible for several pelvic floor disorders, in particular urogenital prolapses.

  6. Hydrogel-coated fiber Bragg grating sensor for pH monitoring

    Science.gov (United States)

    Pabbisetti, Vayu Nandana Kishore; Madhuvarasu, Sai Shankar

    2016-06-01

    We present a fiber-optic wavelength-modulated sensor for pH applications. Fiber Bragg grating (FBG) is functionalized with a stimulus-responsive hydrogel that induces a strain on FBG due to mechanical expansion of the gel in response to ambient pH changes. The gel is synthesized from the blends of poly (vinyl alcohol)/poly (acrylic acid). The induced strain results in a shift of FBG reflected peak that is monitored by an interrogator. The sensor system shows good linearity in the acidic pH range of 3 to 7 with a sensitivity of 12.16 pm/pH. In addition, it shows good repeatability and oscillator behavior, which proves it to be fit for pH sensing applications.

  7. Supersymmetric Bragg gratings

    CERN Document Server

    Longhi, Stefano

    2015-01-01

    The supersymmetric (SUSY) structure of coupled-mode equations that describe scattering of optical waves in one-dimensional Bragg gratings is highlighted. This property can find applications to the synthesis of special Bragg filters and distributed-feedback (DFB) optical cavities. In particular, multiple SUSY (Darboux-Crum) transformations can be used to synthesize DFB filters with any desired number of resonances at target frequencies. As an example, we describe the design of a DFB structure with a set of equally-spaced resonances, i.e. a frequency comb transmission filter.

  8. Supersymmetric Bragg gratings

    International Nuclear Information System (INIS)

    The supersymmetric (SUSY) structure of coupled-mode equations that describe scattering of optical waves in one-dimensional Bragg gratings is highlighted. This property can find applications to the synthesis of special Bragg filters and distributed-feedback (DFB) optical cavities. In particular, multiple SUSY (Darboux–Crum) transformations can be used to synthesize DFB filters with any desired number of resonances at target frequencies. As an example, we describe the design of a DFB structure with a set of equally-spaced resonances, i.e. a frequency comb transmission filter. (paper)

  9. Fiber Bragg Grating Sensor/Systems for In-Flight Wing Shape Monitoring of Unmanned Aerial Vehicles (UAVs)

    Science.gov (United States)

    Parker, Allen; Richards, Lance; Ko, William; Piazza, Anthony; Tran, Van

    2006-01-01

    A viewgraph presentation describing an in-flight wing shape measurement system based on fiber bragg grating sensors for use in Unmanned Aerial Vehicles (UAV) is shown. The topics include: 1) MOtivation; 2) Objective; 3) Background; 4) System Design; 5) Ground Testing; 6) Future Work; and 7) Conclusions

  10. Measurement of Temperature Field for the Spindle of Machine Tool Based on Optical Fiber Bragg Grating Sensors

    OpenAIRE

    Liu, Mingyao; Zhang, Erlong; Zhou, Zude; Tan, Yuegang; Liu, Yi

    2013-01-01

    The change of spindle temperature field is an important factor which influences machining precision. Many methods of spindle temperature field measurement have been proposed. However, most of the methods are based on the electric temperature sensors. There exist some defects (e.g., anti-interference, multiplexing, and stability capacity are poor). To increase the temperature sensitivity and reduce strain sensitivity of the bare Fiber Bragg Grating (FBG) sensor, a cassette packaged FBG sensor ...

  11. Dynamic Strain Measurements on Automotive and Aeronautic Composite Components by Means of Embedded Fiber Bragg Grating Sensors

    OpenAIRE

    Alfredo Lamberti; Gabriele Chiesura; Geert Luyckx; Joris Degrieck; Markus Kaufmann; Steve Vanlanduit

    2015-01-01

    The measurement of the internal deformations occurring in real-life composite components is a very challenging task, especially for those components that are rather difficult to access. Optical fiber sensors can overcome such a problem, since they can be embedded in the composite materials and serve as in situ sensors. In this article, embedded optical fiber Bragg grating (FBG) sensors are used to analyze the vibration characteristics of two real-life composite components. The first component...

  12. Digital monitoring and health diagnosis for mechanical equipment operation safety based on fiber Bragg grating sensor

    Institute of Scientific and Technical Information of China (English)

    Zude ZHOU; Desheng JIANG; Quan LIU

    2009-01-01

    This paper introduces fiber Bragg grating (FBG) based on a fiber optic grating sensor developed to be embedded on mechanical equipment for digital monitoring and health diagnosis. The theoretical and experimental researches on the new-style FBG sensor (FBGS) technology, high-speed demodulation, and data transmission are discussed. The transmission characteristics between the FBG and the detection interface, modeling and compensation method for online distributed multi-parameter digital monitoring and methods for data processing, synchronous sampling, and long-term dynamic digital monitoring using embedded technology are also presented. The acquired information by an FBGS can be used for the optimization of maintenance schedules and refinement of mechanical equipment design. It is a chal-lenge to gather real-time data from components working at high speed and in a severe environment of high temperature, high pressure, and high rotation speed. Currently, there are no sensors or technologies available for digital monitoring and health diagnosis under this rigorous situation for use in mechanical engineering operation safety. As a result, this paper introduces an online distributed and integrated digital monitoring system and health diagnosis. The new principle and new method will contribute to modem measurements in science and technology, mechanical engineering, and large mechanical equipment operation safety.

  13. Sensor based on macrobent fiber Bragg grating structure for simultaneous measurement of refractive index and temperature.

    Science.gov (United States)

    Liu, Tiegen; Chen, Yaofei; Han, Qun; Liu, Fangchao; Yao, Yunzhi

    2016-02-01

    A novel and compact all-fiber sensor based on a macrobent fiber Bragg grating (FBG) structure for simultaneous measurement of refractive index (RI) and temperature is proposed and experimentally investigated. The sensor can be easily fabricated by properly bending an FBG. The bending causes interference between the core mode and the whispering gallery mode, which induces another kind of dip in the transmission spectra of the sensor besides the sharp one of the FBG. Because the two kinds of dips respond differently to the surrounding RI and temperature, these two parameters can be unambiguously measured by the sensor. A sample sensor was fabricated and experimentally investigated, and RI sensitivity of 165.9276 nm/RIU in the range from 1.3330 to 1.3785 and temperature sensitivity of 31.7 pm/°C were achieved. This sensor provides a convenient and economical way for applications where temperature and RI have to be simultaneously measured. PMID:26836081

  14. Peak wavelength interrogation of fiber Bragg grating sensors during impact events

    International Nuclear Information System (INIS)

    In this paper, we embed fiber Bragg grating (FBG) sensors in graphite fiber–epoxy woven composite laminates to detect evolving damage modes. The peak wavelengths of the FBG sensors are interrogated at 625 and 295 kHz, while the laminates are subjected to 11.0 J low-velocity impact events. It is demonstrated that 295 kHz interrogation is sufficient for accurately collecting the dynamic response of the sensors. The FBG sensors embedded at the laminate midplanes successfully reconstructed the global laminate response to impact. The maximum and full width at half-maximum (FWHM) for the relative strain histories demonstrated the same trends as the maximum and FWHM of the contact force histories measured from the impactor. More noise was present in the strain histories obtained from the FBG sensors than the contact force histories, as the embedded FBGs were sensitive to local perturbations in the stress state. The FBG sensors embedded below the midplane of the laminate were closer to the damage regions and measured complex strain histories. In one case, this strain history revealed the presence of delamination

  15. Temperature-insensitive fiber Bragg grating displacement sensor based on a thin-wall ring

    Science.gov (United States)

    Tao, Sicong; Dong, Xiaopeng; Lai, Bowen

    2016-08-01

    The study on strain distribution of a thin-wall ring is presented and a bandwidth-demodulated displacement sensor based on a fiber Bragg grating (FBG) is proposed. The FBG is glued onto the inner surface of a spring steel ring, and it is found that its bandwidth is linearly changed with the displacement variation of the top point of the ring due to the ring-compression-induced gradient strain. The PD output responses of different grating lengths to the same dimension of the ring are investigated. Experimental results show that the high sensitivity and accuracy of 0.567 nm mm-1 and ±0.04 mm using 10 mm grating is achieved within a displacement range of 0-3.5 mm. The designed structure has a higher 3dB-bandwidth tuning ratio of 0.057 nm mm-2. A temperature stability better than ±0.02 mm over the temperature range from 0 to 60 °C is demonstrated.

  16. Influence of Fiber Bragg Grating Spectrum Degradation on the Performance of Sensor Interrogation Algorithms

    Directory of Open Access Journals (Sweden)

    Alfredo Lamberti

    2014-12-01

    Full Text Available The working principle of fiber Bragg grating (FBG sensors is mostly based on the tracking of the Bragg wavelength shift. To accomplish this task, different algorithms have been proposed, from conventional maximum and centroid detection algorithms to more recently-developed correlation-based techniques. Several studies regarding the performance of these algorithms have been conducted, but they did not take into account spectral distortions, which appear in many practical applications. This paper addresses this issue and analyzes the performance of four different wavelength tracking algorithms (maximum detection, centroid detection, cross-correlation and fast phase-correlation when applied to distorted FBG spectra used for measuring dynamic loads. Both simulations and experiments are used for the analyses. The dynamic behavior of distorted FBG spectra is simulated using the transfer-matrix approach, and the amount of distortion of the spectra is quantified using dedicated distortion indices. The algorithms are compared in terms of achievable precision and accuracy. To corroborate the simulation results, experiments were conducted using three FBG sensors glued on a steel plate and subjected to a combination of transverse force and vibration loads. The analysis of the results showed that the fast phase-correlation algorithm guarantees the best combination of versatility, precision and accuracy.

  17. Influence of Fiber Bragg Grating Spectrum Degradation on the Performance of Sensor Interrogation Algorithms

    Science.gov (United States)

    Lamberti, Alfredo; Vanlanduit, Steve; De Pauw, Ben; Berghmans, Francis

    2014-01-01

    The working principle of fiber Bragg grating (FBG) sensors is mostly based on the tracking of the Bragg wavelength shift. To accomplish this task, different algorithms have been proposed, from conventional maximum and centroid detection algorithms to more recently-developed correlation-based techniques. Several studies regarding the performance of these algorithms have been conducted, but they did not take into account spectral distortions, which appear in many practical applications. This paper addresses this issue and analyzes the performance of four different wavelength tracking algorithms (maximum detection, centroid detection, cross-correlation and fast phase-correlation) when applied to distorted FBG spectra used for measuring dynamic loads. Both simulations and experiments are used for the analyses. The dynamic behavior of distorted FBG spectra is simulated using the transfer-matrix approach, and the amount of distortion of the spectra is quantified using dedicated distortion indices. The algorithms are compared in terms of achievable precision and accuracy. To corroborate the simulation results, experiments were conducted using three FBG sensors glued on a steel plate and subjected to a combination of transverse force and vibration loads. The analysis of the results showed that the fast phase-correlation algorithm guarantees the best combination of versatility, precision and accuracy. PMID:25521386

  18. Fiber Optic Sensors for Health Monitoring of Morphing Airframes. Part 1; Bragg Grating Strain and Temperature Sensor

    Science.gov (United States)

    Wood, Karen; Brown, Timothy; Rogowski, Robert; Jensen, Brian

    2000-01-01

    Fiber optic sensors are being developed for health monitoring of future aircraft. Aircraft health monitoring involves the use of strain, temperature, vibration and chemical sensors to infer integrity of the aircraft structure. Part 1 of this two part series describes sensors that will measure load and temperature signatures of these structures. In some cases a single fiber may be used for measuring these parameters. Part 2 will describe techniques for using optical fibers to monitor composite cure in real time during manufacture and to monitor in-service integrity of composite structures using a single fiber optic sensor capable of measuring multiple chemical and physical parameters. The facilities for fabricating optical fiber and associated sensors and the methods of demodulating Bragg gratings for strain measurement will be described.

  19. Residual internal stress optimization for EPON 828/DEA thermoset resin using fiber Bragg grating sensors

    Science.gov (United States)

    Rohr, Garth D.; Rasberry, Roger D.; Kaczmarowski, Amy K.; Stavig, Mark E.; Gibson, Cory S.; Udd, Eric; Roach, Allen R.; Nation, Brendan

    2015-05-01

    Internal residual stresses and overall mechanical properties of thermoset resins are largely dictated by the curing process. It is well understood that fiber Bragg grating (FBG) sensors can be used to evaluate temperature and cure induced strain while embedded during curing. Herein, is an extension of this work whereby we use FBGs as a probe for minimizing the internal residual stress of an unfilled and filled Epon 828/DEA resin. Variables affecting stress including cure cycle, mold (release), and adhesion promoting additives will be discussed and stress measurements from a strain gauge pop-off test will be used as comparison. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  20. Production and Characterization of Polycarbonate Microstructured Polymer Optical Fiber Bragg Grating Sensor

    DEFF Research Database (Denmark)

    Fasano, Andrea; Woyessa, Getinet; Stajanca, P.;

    2015-01-01

    We present the fabrication and characterization of a polycarbonate (PC) microstructured polymer optical fiber (mPOF) and the writing of a fiber Bragg grating (FBG) in it to obtain a polymer optical FBG sen-sor. The manufacturing process of the PC mPOF consists of multiple consecutive stages......, such as casting of pol-ymer granulates into a solid rod, machining and drilling of a 3-ring hexagonal lattice of holes into it, and finally drawing into fiber. We demonstrate that the obtained PC mPOF is photosensitive and FBGs can be conveniently inscribed into it, thereby enabling FBG-based temperature...... and strain sensing. The PC optical fibers are for some applications an attractive alternative to conventional materials used in POF fabrication, such as polymethyl methacrylate (PMMA). In general, PC can be used at temperature up to 120 °C and breaks at considerably higher strains than PMMA....

  1. Interrogation of fiber-Bragg-grating temperature and strain sensors with a temperature-stabilized VCSEL

    Science.gov (United States)

    Mizunami, Toru; Yamada, Taichi; Tsuchiya, Satoshi

    2016-07-01

    The interrogation of fiber-Bragg-grating (FBG) sensors using a vertical-cavity surface-emitting laser (VCSEL) is discussed. A long-wavelength (1.54 μm) VCSEL was used as a wavelength-tunable source by variation in the current. Temperature stabilization was performed with a thermoelectric device. Characteristics of temperature and strain sensing were investigated. FBGs with different reflectivities were compared. For temperature sensing, the root-mean-square error in the measurement was reduced to 1/3 that without temperature stabilization. The dependence of the measurement error on the reflectivities of the FBGs was investigated. The measurement error was larger for FBGs with lower reflectivities in both temperature and strain sensing. Improvement on the sensing with low-reflectivity FBGs is discussed.

  2. Structural Health Monitoring of Superconducting Magnets at CERN Using Fiber Bragg Grating Sensors

    CERN Document Server

    Chiuchiolo, A; Perez, J C; Bajas, H; Guinchard, M; Giordano, M; Breglio, G; Consales, M; Cusano, A

    2014-01-01

    The use of Fiber Bragg Grating sensors is becoming particularly challenging for monitoring different parameters in extreme operative conditions such as ultra-low temperatures, high electromagnetic fields and strong mechanical stresses. This work reports the use of the FBG for a new generation of accelerator magnets with the goal to develop an adequate sensing technology able to provide complementary or alternative information to the conventional strain gauges through the whole service life of the magnet. The study is focused on the mechanical performances of the magnet structure, which has to preserve the sensitive coils from any damage during the entire magnet fabrication process preventing even microscopic movements of the winding that can eventually initiate a transition from superconducting to normal conducting state of the material used (called in the specific literature as “quench”). The FBGs have been glued on the aluminium structure of two magnets prototypes by using an adhesive suitable for cryog...

  3. Detuned Plasmonic Bragg Grating Sensor Based on a Defect Metal-Insulator-Metal Waveguide

    Science.gov (United States)

    Qu, Shinian; Song, Ci; Xia, Xiushan; Liang, Xiuye; Tang, Baojie; Hu, Zheng-Da; Wang, Jicheng

    2016-01-01

    A nanoscale Bragg grating reflector based on the defect metal-insulator-metal (MIM) waveguide is developed and numerically simulated by using the finite element method (FEM). The MIM-based structure promises a highly tunable broad stop-band in transmission spectra. The narrow transmission window is shown to appear in the previous stop-band by changing the certain geometrical parameters. The central wavelengths can be controlled easily by altering the geographical parameters. The development of surface plasmon polarition (SPP) technology in metallic waveguide structures leads to more possibilities of controlling light at deep sub-wavelengths. Its attractive ability of breaking the diffraction limit contributes to the design of optical sensors. PMID:27240381

  4. Note: A concrete erosion sensor based on a chirped fibre optic Bragg grating.

    Science.gov (United States)

    Kanopoulos, Patrick; Xia, Kaiwen; Gu, Xijia; Amirchoupani, Ardavan; Yao, Wei

    2015-12-01

    Erosion of concrete surfaces in major civil structures is a common problem, which in certain circumstances can undermine the structural and operational integrities of the structure. The manual monitoring of the erosion process can be difficult and dangerous under certain circumstances (such as within hydrotunnels and spillways of dams). This paper describes a concrete erosion sensor based on a chirped fibre Bragg grating (FBG) which is able to monitor the extent of concrete erosion at a single point to sub-millimetre accuracy. The chirped FBG length embedded below the concrete surface decreases as a result of concrete erosion and consequently the reflected light spectrum bandwidth narrows. A simple procedure is presented to determine the extent of erosion, and this procedure is applied to an experimental demonstration of the sensing device.

  5. A Fiber Bragg Grating Sensing-Based Micro-Vibration Sensor and Its Application.

    Science.gov (United States)

    Li, Tianliang; Tan, Yuegang; Zhou, Zude

    2016-01-01

    This paper proposes a fiber Bragg grating sensing-based micro-vibration sensor. The optical fiber has been directly treated as an elastomer to design the micro-vibration sensor, which possesses two FBGs. The mass is fixed on the middle of the fiber, and the vertical vibration of the mass has been converted into the axial tension/compression of the fiber. The principle of the sensor has been introduced, and the experiment conclusions show that the sensor sensitivity is 2362 pm/g within the range of 200-1200 mm/s², which is consistent with theoretical analysis sensitivity of 2532.6 pm/g, and it shows an excellent linearity of 1.376%, while the resonant frequency of the sensor is 34 Hz, and the flat frequency range resides in the 0-22 Hz range. When used to measure micro-vibrations, its measured frequency relative error is less than 1.69% compared with the values acquired with a MEMS accelerometer, and the amplitude values of its measured vibration signal are consistent with the MEMS accelerometer under different excitation conditions too, so it can effectively realize the micro-vibration measurements. PMID:27092507

  6. A fiber Bragg grating sensor for detection of liquid water in concrete structures

    International Nuclear Information System (INIS)

    Concrete structures rely greatly on the integrity of their supporting rebars to remain serviceable for their intended purposes. Unfortunately, rebars are vulnerable to corrosion due to the ingress of water from the environment, which often also carries a multitude of ionic particles that encourage corrosion. Liquid phase water may enter the structure through cracks that may not be obvious to human observation. Thus, a fiber Bragg grating sensor was designed that is able to detect (i.e. ‘on–off’) the presence of liquid water in order to provide an early warning signal for the ingress of water. Two tests were conducted to verify the functionality of the sensor: the first experiment tested the repeatability of the sensor to cyclic input of various volumes of water, and the second tested the sensor’s response to flooding conditions. The sensor showed a good repeatability, with fast response times (<10 min to reach a level guaranteeing the presence of water) and a recovery time of 11–15 h, depending on the input volume. The flooding test showed similar performance and viability of the sensor during flooding conditions. (paper)

  7. The sensitivity enhancement of tilted fibre Bragg grating sensors with polarization dependent resonant nano-scale coatings

    CERN Document Server

    Bialiayeu, Aliaksandr

    2015-01-01

    Fibre Bragg grating sensors have emerged as a simple, inexpensive, accurate, sensitive and reliable platform, a viable alternative to the traditional bulkier optical sensor platforms. In this work we present an extensive theoretical analysis of the tilted fibre Bragg grating sensor (TFBG) with a particular focus on its polarization-dependent properties. We have developed a highly efficient computer model capable of providing the full characterization of the TFBG device in less then $3$~minutes for a given state of incident light polarization. As a result, the polarization-dependent spectral response, the field distribution at the sensor surface as well as the fine structure of particular resonances have become accessible for theoretical analysis. As a part of this computer model we have developed a blazingly fast full-vector complex mode solver, capable of handling cylindrical waveguides of an arbitrary complex refractive index profile. Along with the theoretical study we have investigated optical properties ...

  8. Fiber Bragg grating strain sensors to monitor and study active volcanoes

    Science.gov (United States)

    Sorrentino, Fiodor; Beverini, Nicolò; Carbone, Daniele; Carelli, Giorgio; Francesconi, Francesco; Gambino, Salvo; Giacomelli, Umberto; Grassi, Renzo; Maccioni, Enrico; Morganti, Mauro

    2016-04-01

    Stress and strain changes are among the best indicators of impending volcanic activity. In volcano geodesy, borehole volumetric strain-meters are mostly utilized. However, they are not easy to install and involve high implementation costs. Advancements in opto-electronics have allowed the development of low-cost sensors, reliable, rugged and compact, thus particularly suitable for field application. In the framework of the EC FP7 MED-SUV project, we have developed strain sensors based on the fiber Bragg grating (FBG) technology. In comparison with previous implementation of the FBG technology to study rock deformations, we have designed a system that is expected to offer a significantly higher resolution and accuracy in static measurements and a smooth dynamic response up to 100 Hz, implying the possibility to observe seismic waves. The system performances are tailored to suit the requirements of volcano monitoring, with special attention to power consumption and to the trade-off between performance and cost. Preliminary field campaigns were carried out on Mt. Etna (Italy) using a prototypal single-axis FBG strain sensor, to check the system performances in out-of-the-lab conditions and in the harsh volcanic environment (lack of mains electricity for power, strong diurnal temperature changes, strong wind, erosive ash, snow and ice during the winter time). We also designed and built a FBG strain sensor featuring a multi-axial configuration which was tested and calibrated in the laboratory. This instrument is suitable for borehole installation and will be tested on Etna soon.

  9. An intrusion detection system for the protection of railway assets using Fiber Bragg Grating sensors.

    Science.gov (United States)

    Catalano, Angelo; Bruno, Francesco Antonio; Pisco, Marco; Cutolo, Antonello; Cusano, Andrea

    2014-01-01

    We demonstrate the ability of Fiber Bragg Gratings (FBGs) sensors to protect large areas from unauthorized activities in railway scenarios such as stations or tunnels. We report on the technological strategy adopted to protect a specific depot, representative of a common scenario for security applications in the railway environment. One of the concerns in the protection of a railway area centers on the presence of rail-tracks, which cannot be obstructed with physical barriers. We propose an integrated optical fiber system composed of FBG strain sensors that can detect human intrusion for protection of the perimeter combined with FBG accelerometer sensors for protection of rail-track access. Several trials were carried out in indoor and outdoor environments. The results demonstrate that FBG strain sensors bonded under a ribbed rubber mat enable the detection of intruder break-in via the pressure induced on the mat, whereas the FBG accelerometers installed under the rails enable the detection of intruders walking close to the railroad tracks via the acoustic surface waves generated by footsteps. Based on a single enabling technology, this integrated system represents a valuable intrusion detection system for railway security and could be integrated with other sensing functionalities in the railway field using fiber optic technology. PMID:25268920

  10. Internal and External Temperature Monitoring of a Li-Ion Battery with Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Novais, Susana; Nascimento, Micael; Grande, Lorenzo; Domingues, Maria Fátima; Antunes, Paulo; Alberto, Nélia; Leitão, Cátia; Oliveira, Ricardo; Koch, Stephan; Kim, Guk Tae; Passerini, Stefano; Pinto, João

    2016-08-30

    The integration of fiber Bragg grating (FBG) sensors in lithium-ion cells for in-situ and in-operando temperature monitoring is presented herein. The measuring of internal and external temperature variations was performed through four FBG sensors during galvanostatic cycling at C-rates ranging from 1C to 8C. The FBG sensors were placed both outside and inside the cell, located in the center of the electrochemically active area and at the tab-electrode connection. The internal sensors recorded temperature variations of 4.0 ± 0.1 °C at 5C and 4.7 ± 0.1 °C at 8C at the center of the active area, and 3.9 ± 0.1 °C at 5C and 4.0 ± 0.1 °C at 8C at the tab-electrode connection, respectively. This study is intended to contribute to detection of a temperature gradient in real time inside a cell, which can determine possible damage in the battery performance when it operates under normal and abnormal operating conditions, as well as to demonstrate the technical feasibility of the integration of in-operando microsensors inside Li-ion cells.

  11. Fiber Optic Bragg Grating Sensors for Thermographic Detection of Subsurface Anomalies

    Science.gov (United States)

    Allison, Sidney G.; Winfree, William P.; Wu, Meng-Chou

    2009-01-01

    Conventional thermography with an infrared imager has been shown to be an extremely viable technique for nondestructively detecting subsurface anomalies such as thickness variations due to corrosion. A recently developed technique using fiber optic sensors to measure temperature holds potential for performing similar inspections without requiring an infrared imager. The structure is heated using a heat source such as a quartz lamp with fiber Bragg grating (FBG) sensors at the surface of the structure to detect temperature. Investigated structures include a stainless steel plate with thickness variations simulated by small platelets attached to the back side using thermal grease. A relationship is shown between the FBG sensor thermal response and variations in material thickness. For comparison, finite element modeling was performed and found to agree closely with the fiber optic thermography results. This technique shows potential for applications where FBG sensors are already bonded to structures for Integrated Vehicle Health Monitoring (IVHM) strain measurements and can serve dual-use by also performing thermographic detection of subsurface anomalies.

  12. An Intrusion Detection System for the Protection of Railway Assets Using Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Angelo Catalano

    2014-09-01

    Full Text Available We demonstrate the ability of Fiber Bragg Gratings (FBGs sensors to protect large areas from unauthorized activities in railway scenarios such as stations or tunnels. We report on the technological strategy adopted to protect a specific depot, representative of a common scenario for security applications in the railway environment. One of the concerns in the protection of a railway area centers on the presence of rail-tracks, which cannot be obstructed with physical barriers. We propose an integrated optical fiber system composed of FBG strain sensors that can detect human intrusion for protection of the perimeter combined with FBG accelerometer sensors for protection of rail-track access. Several trials were carried out in indoor and outdoor environments. The results demonstrate that FBG strain sensors bonded under a ribbed rubber mat enable the detection of intruder break-in via the pressure induced on the mat, whereas the FBG accelerometers installed under the rails enable the detection of intruders walking close to the railroad tracks via the acoustic surface waves generated by footsteps. Based on a single enabling technology, this integrated system represents a valuable intrusion detection system for railway security and could be integrated with other sensing functionalities in the railway field using fiber optic technology.

  13. Gauge factors of fibre Bragg grating strain sensors in different types of optical fibres

    International Nuclear Information System (INIS)

    Gauge factors of fibre Bragg grating (FBG)-based strain sensors that had been inscribed into three different types of optical fibres, which differ in core diameters and doping concentrations, were determined at room temperature with high accuracy. Repeated measurements were carried out with several samples of each type of fibre to allow statistical evaluations. For each type, the gauge factors were measured in two configurations: when the bare fibres were glued on a specimen at the location of the FBG and when they were vertically suspended and not bonded to any structure at the location of the FBG. By combining the results of both configurations, the strain transfer ratio of the gluing process and the strain-optic coefficient, peff, of the different types of fibres were determined. The strain-optic coefficient was found to vary up to 1.5% for the different types of optical fibres. The strain transfer ratio was obtained to be close to unity (>99%), showing the high quality of the gluing technique employed. The investigations demonstrate that highly accurate strain sensing is possible with fibre-optic strain sensors. The results are important for the development of accurate and reliable attaching techniques for coated sensor fibres and fibre-optic sensor patches. (paper)

  14. Internal and External Temperature Monitoring of a Li-Ion Battery with Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Novais, Susana; Nascimento, Micael; Grande, Lorenzo; Domingues, Maria Fátima; Antunes, Paulo; Alberto, Nélia; Leitão, Cátia; Oliveira, Ricardo; Koch, Stephan; Kim, Guk Tae; Passerini, Stefano; Pinto, João

    2016-01-01

    The integration of fiber Bragg grating (FBG) sensors in lithium-ion cells for in-situ and in-operando temperature monitoring is presented herein. The measuring of internal and external temperature variations was performed through four FBG sensors during galvanostatic cycling at C-rates ranging from 1C to 8C. The FBG sensors were placed both outside and inside the cell, located in the center of the electrochemically active area and at the tab-electrode connection. The internal sensors recorded temperature variations of 4.0 ± 0.1 °C at 5C and 4.7 ± 0.1 °C at 8C at the center of the active area, and 3.9 ± 0.1 °C at 5C and 4.0 ± 0.1 °C at 8C at the tab-electrode connection, respectively. This study is intended to contribute to detection of a temperature gradient in real time inside a cell, which can determine possible damage in the battery performance when it operates under normal and abnormal operating conditions, as well as to demonstrate the technical feasibility of the integration of in-operando microsensors inside Li-ion cells. PMID:27589749

  15. A fiber Bragg grating--bimetal temperature sensor for solar panel inverters.

    Science.gov (United States)

    Ismail, Mohd Afiq; Tamchek, Nizam; Hassan, Muhammad Rosdi Abu; Dambul, Katrina D; Selvaraj, Jeyrai; Rahim, Nasrudin Abd; Sandoghchi, Reza; Adikan, Faisal Rafiq Mahamd

    2011-01-01

    This paper reports the design, characterization and implementation of a fiber Bragg grating (FBG)-based temperature sensor for an insulted-gate Bipolar transistor (IGBT) in a solar panel inverter. The FBG is bonded to the higher coefficient of thermal expansion (CTE) side of a bimetallic strip to increase its sensitivity. Characterization results show a linear relationship between increasing temperature and the wavelength shift. It is found that the sensitivity of the sensor can be categorized into three characterization temperature regions between 26 °C and 90 °C. The region from 41 °C to 90 °C shows the highest sensitivity, with a value of 14 pm/°C. A new empirical model that considers both temperature and strain effects has been developed for the sensor. Finally, the FBG-bimetal temperature sensor is placed in a solar panel inverter and results confirm that it can be used for real-time monitoring of the IGBT temperature.

  16. A fiber Bragg grating--bimetal temperature sensor for solar panel inverters.

    Science.gov (United States)

    Ismail, Mohd Afiq; Tamchek, Nizam; Hassan, Muhammad Rosdi Abu; Dambul, Katrina D; Selvaraj, Jeyrai; Rahim, Nasrudin Abd; Sandoghchi, Reza; Adikan, Faisal Rafiq Mahamd

    2011-01-01

    This paper reports the design, characterization and implementation of a fiber Bragg grating (FBG)-based temperature sensor for an insulted-gate Bipolar transistor (IGBT) in a solar panel inverter. The FBG is bonded to the higher coefficient of thermal expansion (CTE) side of a bimetallic strip to increase its sensitivity. Characterization results show a linear relationship between increasing temperature and the wavelength shift. It is found that the sensitivity of the sensor can be categorized into three characterization temperature regions between 26 °C and 90 °C. The region from 41 °C to 90 °C shows the highest sensitivity, with a value of 14 pm/°C. A new empirical model that considers both temperature and strain effects has been developed for the sensor. Finally, the FBG-bimetal temperature sensor is placed in a solar panel inverter and results confirm that it can be used for real-time monitoring of the IGBT temperature. PMID:22164098

  17. Real-time weigh-in-motion measurement using fiber Bragg grating sensors

    Science.gov (United States)

    Huang, Ying; Palek, Leonard; Strommen, Robert; Worel, Ben; Chen, Genda

    2014-03-01

    Overloading truck loads have long been one of the key reasons for accelerating road damage, especially in rural regions where the design loads are expected to be small and in the cold regions where the wet-and-dry cycle places a significant role. To control the designed traffic loads and further guide the road design in future, periodical weight stations have been implemented for double check of the truck loads. The weight stations give chances for missing measurement of overloaded vehicles, slow down the traffic, and require additional labors. Infrastructure weight-in-motion sensors, on the other hand, keep consistent traffic flow and monitor all types of vehicles on roads. However, traditional electrical weight-in-motion sensors showed high electromagnetic interference (EMI), high dependence on environmental conditions such as moisture, and relatively short life cycle, which are unreliable for long-term weigh-inmotion measurements. Fiber Bragg grating (FBG) sensors, with unique advantages of compactness, immune to EMI and moisture, capability of quasi-distributed sensing, and long life cycle, will be a perfect candidate for long-term weigh-in-motion measurements. However, the FBG sensors also surfer from their frangible nature of glass materials for a good survive rate during sensor installation. In this study, the FBG based weight-in-motion sensors were packaged by fiber reinforced polymer (FRP) materials and further validated at MnROAD facility, Minnesota DOT (MnDOT). The design and layout of the FRP-FBG weight-in-motion sensors, their field test setup, data acquisition, and data analysis will be presented. Upon validation, the FRP-FBG sensors can be applied weigh-in-motion measurement to assistant road managements.

  18. Fiber Optic Fabry-Perot Current Sensor Integrated with Magnetic Fluid Using a Fiber Bragg Grating Demodulation.

    Science.gov (United States)

    Xia, Ji; Wang, Qi; Liu, Xu; Luo, Hong

    2015-07-09

    An optical fiber current sensor based on Fabry-Perot interferometer using a fiber Bragg grating demodulation is proposed. Magnetic fluid is used as a sensitive medium in fiber optical Fabry-Perot (F-P) cavity for the optical characteristic of magnetic-controlled refractive index. A Fiber Bragg grating (FBG) is connected after the F-P interferometer which is used to reflect the optical power at the Bragg wavelength of the interference transmission spectrum. The corresponding reflective power of the FBG will change with different external current intensity, due to the shift on the interference spectrum of the F-P interferometer. The sensing probe has the advantages of convenient measurement for its demodulation, low cost and high current measurement accuracy on account of its sensing structure. Experimental results show that an optimal sensitivity of 0.8522 nw/A and measurement resolution of 0.001 A is obtained with a FBG at 1550 nm with 99% reflectivity.

  19. Cuspal Displacement Induced by Bulk Fill Resin Composite Polymerization: Biomechanical Evaluation Using Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Vinagre, Alexandra; Ramos, João; Alves, Sofia; Messias, Ana; Alberto, Nélia; Nogueira, Rogério

    2016-01-01

    Polymerization shrinkage is a major concern to the clinical success of direct composite resin restorations. The aim of this study was to compare the effect of polymerization shrinkage strain of two resin composites on cuspal movement based on the use of fiber Bragg grating (FBG) sensors. Twenty standardized Class II cavities prepared in upper third molars were allocated into two groups (n = 10). Restorations involved the bulk fill placement of conventional microhybrid resin composite (Esthet•X® HD, Dentsply DeTrey) (Group 1) or flowable "low-shrinkage" resin composite (SDR™, Dentsply DeTrey) (Group 2). Two FBG sensors were used per restoration for real-time measurement of cuspal linear deformation and temperature variation. Group comparisons were determined using ANCOVA (α = 0.05) considering temperature as the covariate. A statistically significant correlation between cuspal deflection, time, and material was observed (p < 0.01). Cuspal deflection reached 8.8 μm (0.23%) and 7.8 μm (0.20%) in Groups 1 and 2, respectively. When used with bulk fill technique, flowable resin composite SDR™ induced significantly less cuspal deflection than the conventional resin composite Esthet•X® HD (p = 0.015) and presented a smoother curve slope during the polymerization. FBG sensors appear to be a valid tool for accurate real-time monitoring of cuspal deformation. PMID:27190517

  20. Lamb wave detection in prepreg composite materials with fibre Bragg grating sensors

    Science.gov (United States)

    Miesen, Nick; Mizutani, Yoshihiro; Groves, Roger M.; Sinke, Jos; Benedictus, Rinze

    2011-04-01

    This paper demonstrates that existing Structural Health Monitoring (SHM) techniques have potential during the production phase in addition to their application for maintenance and for in-flight monitoring. Flaws occur during composite fabrication in industry, due to an imperfect process control and human errors. This decreases production efficiency and increases costs. In this paper, the monitoring of Lamb waves in unidirectional carbon fibre (UD-CFRP) prepreg material is demonstrated using both Fibre Bragg Gratings (FBG)s and piezolectric acoustic sensors, and that these SHM sensors may be used for flaw detection and production monitoring. The detection of Lamb waves in a one ply thick sheet of prepreg UD-CFRP material is demonstrated for an FBG sensor aligned with the carbon fibre orientation and bonded to the surface of the prepreg, Furthermore, the velocity of Lamb waves in prepreg UD-CFRP in different orientations is investigated. Finally the successful detection of a material crack in a prepreg UD-CFRP sheet using the Lamb wave detection method is demonstrated.

  1. Quasi-distributed fiber bragg grating array sensor for furnace applications

    Science.gov (United States)

    Reddy, P. Saidi; Sai Prasad, R. L. N.; Sen Gupta, D.; Sai Shankar, M.; Srimannarayana, K.; Ravinder Reddy, P.

    2012-05-01

    An experimental work on distributed temperature sensing making use of the fiber Bragg grating (FBG) array sensor for possible applications in the monitoring of the temperature profile in high temperature boilers is presented. A special sensor has been designed for this purpose which consists of four FBGs (of wavelengths λ B1 =1545.8 nm, λ B2 =1547 nm, λ B3 =1550.8 nm, λ B4 =1555.5 nm at 30 °C) written in the hydrogen-loaded fiber in line. All the FBGs are encapsulated inside a stainless steel tube using the rigid probe technique for avoiding micro cracks. The spatial distribution of the temperature profile inside a prototype boiler was measured experimentally both in horizontal and vertical directions employing the above sensor, and the results are presented. Further, the finite element simulation has been carried out by using ANSYS R11 software to predict temperature contours in the boiler, and the experimental and predicted results were found to be closely matching.

  2. A novel application of Fiber Bragg Grating (FBG) sensors in MPGD

    CERN Document Server

    Benussi, Luigi

    2015-01-01

    We present a novel application of Fiber Bragg Grating (FBG) sensors in the construction and characterisation of MPGD, with particular attention to the realisation of the largest triple GEM chambers so far operated, the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 qm active area each, employing three GEM foils per chamber, to be installed in the forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM foils that are mechanically stretched in order to secure their flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. So far FBGs have been used in high energy physics mainly as high precision positioning and re-positioning sensors and as low cost, easy to mount, low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements in material studies. In this work we present a novel use ...

  3. A novel application of Fiber Bragg Grating (FBG) sensors in MPGD

    CERN Document Server

    Abbaneo, D; Abbrescia, M; Abdelalim, A A; Akl, M Abi; Aboamer, O; Acosta, D; Ahmad, A; Ahmed, W; Aleksandrov, A; Aly, R; Altieri, P; Asawatangtrakuldee, C; Aspell, P; Assran, Y; Awan, I; Bally, S; Ban, Y; Banerjee, S; Barashko, V; Barria, P; Bencze, G; Beni, N; Benussi, L; Bhopatkar, V; Bianco, S; Bos, J; Bouhali, O; Braghieri, A; Braibant, S; Buontempo, S; Calabria, C; Caponero, M; Caputo, C; Cassese, F; Castaneda, A; Cauwenbergh, S; Cavallo, F R; Celik, A; Choi, M; Choi, S; Christiansen, J; Cimmino, A; Colafranceschi, S; Colaleo, A; Garcia, A Conde; Czellar, S; Dabrowski, M M; De Lentdecker, G; De Oliveira, R; de Robertis, G; Dildick, S; Dorney, B; Elmetenawee, W; Endroczi, G; Errico, F; Fenyvesi, A; Ferry, S; Furic, I; Giacomelli, P; Golovtsov, V; Guiducci, L; Guilloux, F; Gutierrez, A; Hadjiiska, R M; Hassan, A; Hauser, J; Hoepfner, K; Hohlmann, M; Hoorani, H; Iaydjiev, P; Jeng, Y G; Kamon, T; Karchin, P; Korytov, A; Krutelyov, S; Kumar, A; Kim, H; Lee, J; Lenzi, T; Litov, L; Loddo, F; Madorsky, A; Maerschalk, T; Maggi, M; Magnani, A; Mal, P K; Mandal, K; Marchioro, A; Marinov, A; Masod, R; Majumdar, N; Merlin, J A; Mitselmakher, G; Mohanty, A K; Muhammad, S; Mohapatra, A; Molnar, J; Mukhopadhyay, S; Naimuddin, M; Nuzzo, S; Oliveri, E; Pant, L M; Paolucci, P; Park, I; Passeggio, G; Passamonti, L; Pavlov, B; Philipps, B; Piccolo, D; Pierluigi, D; Postema, H; Baranac, A Puig; Radi, A; Radogna, R; Raffone, G; Ranieri, A; Rashevski, G; Riccardi, C; Rodozov, M; Rodrigues, A; Ropelewski, L; RoyChowdhury, S; Russo, A; Ryu, G; Ryu, M S; Safonov, A; Salva, S; Saviano, G; Sharma, A; Sharma, R; Shah, A H; Shopova, M; Sturdy, J; Sultanov, G; Swain, S K; Szillasi, Z; Tatarinov, A; Tuuva, T; Tytgat, M; Vai, I; Van Stenis, M; Venditti, R; Verhagen, E; Verwilligen, P; Vitulo, P; Volkov, S; Vorobyev, A; Wang, D; Wang, M; Yang, U; Yang, Y; Yonamine, R; Zaganidis, N; Zenoni, F; Zhang, A

    2015-01-01

    We present a novel application of Fiber Bragg Grating (FBG) sensors in the construction and characterisation of Micro Pattern Gaseous Detector (MPGD), with particular attention to the realisation of the largest triple (Gas electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 m2 active area each, employing three GEM foils per chamber, to be installed in the forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM foils that are mechanically stretched in order to secure their flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. So far FBGs have been used in high energy physics mainly as high precision positioning and re-positioning sensors and as low cost, easy to mount, low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurement...

  4. Cuspal Displacement Induced by Bulk Fill Resin Composite Polymerization: Biomechanical Evaluation Using Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Vinagre, Alexandra; Ramos, João; Alves, Sofia; Messias, Ana; Alberto, Nélia; Nogueira, Rogério

    2016-01-01

    Polymerization shrinkage is a major concern to the clinical success of direct composite resin restorations. The aim of this study was to compare the effect of polymerization shrinkage strain of two resin composites on cuspal movement based on the use of fiber Bragg grating (FBG) sensors. Twenty standardized Class II cavities prepared in upper third molars were allocated into two groups (n = 10). Restorations involved the bulk fill placement of conventional microhybrid resin composite (Esthet•X® HD, Dentsply DeTrey) (Group 1) or flowable "low-shrinkage" resin composite (SDR™, Dentsply DeTrey) (Group 2). Two FBG sensors were used per restoration for real-time measurement of cuspal linear deformation and temperature variation. Group comparisons were determined using ANCOVA (α = 0.05) considering temperature as the covariate. A statistically significant correlation between cuspal deflection, time, and material was observed (p resin composite SDR™ induced significantly less cuspal deflection than the conventional resin composite Esthet•X® HD (p = 0.015) and presented a smoother curve slope during the polymerization. FBG sensors appear to be a valid tool for accurate real-time monitoring of cuspal deformation.

  5. Fiber Bragg Grating Sensors Based Monitoring System for Superconducting Accelerator Magnets

    CERN Document Server

    Chiuchiolo, A; Perez, J C; Bajas, H; Consales, M; Giordano, M; Breglio, G; Cusano, A

    2014-01-01

    New generation of accelerator magnets for high energy applications currently designed, manufactured and tested at the European Organization for Nuclear Research (CERN) require the implementation of precise cryogenic sensors with long-term robustness and reliability able to withstand cryogenic temperature and to monitor the mechanical stresses affecting the winding during all the stages of his service life, assembly, cool down and powering. Monitoring the mechanical behavior of the magnet from assembly to operation is a critical task which aims to assure the integrity of the magnet and to safely handle the coils made of new brittle material. This contribution deals with the first successful embedding of Fiber Bragg Grating sensors in a subscale Nb3Sn dipole magnet in order to monitor the strain developed in the coil during the cool down to 1.9 K, the powering up to 15.8 kA and the warm up, offering new perspectives for the development of a complementary sensing technology based on fiber optic sensors.

  6. Fiber Bragg Grating Sensor System for Monitoring Smart Composite Aerospace Structures

    Science.gov (United States)

    Moslehi, Behzad; Black, Richard J.; Gowayed, Yasser

    2012-01-01

    Lightweight, electromagnetic interference (EMI) immune, fiber-optic, sensor- based structural health monitoring (SHM) will play an increasing role in aerospace structures ranging from aircraft wings to jet engine vanes. Fiber Bragg Grating (FBG) sensors for SHM include advanced signal processing, system and damage identification, and location and quantification algorithms. Potentially, the solution could be developed into an autonomous onboard system to inspect and perform non-destructive evaluation and SHM. A novel method has been developed to massively multiplex FBG sensors, supported by a parallel processing interrogator, which enables high sampling rates combined with highly distributed sensing (up to 96 sensors per system). The interrogation system comprises several subsystems. A broadband optical source subsystem (BOSS) and routing and interface module (RIM) send light from the interrogation system to a composite embedded FBG sensor matrix, which returns measurand-dependent wavelengths back to the interrogation system for measurement with subpicometer resolution. In particular, the returned wavelengths are channeled by the RIM to a photonic signal processing subsystem based on powerful optical chips, then passed through an optoelectronic interface to an analog post-detection electronics subsystem, digital post-detection electronics subsystem, and finally via a data interface to a computer. A range of composite structures has been fabricated with FBGs embedded. Stress tensile, bending, and dynamic strain tests were performed. The experimental work proved that the FBG sensors have a good level of accuracy in measuring the static response of the tested composite coupons (down to submicrostrain levels), the capability to detect and monitor dynamic loads, and the ability to detect defects in composites by a variety of methods including monitoring the decay time under different dynamic loading conditions. In addition to quasi-static and dynamic load monitoring, the

  7. Fiber Bragg Grating Based Thermometry

    CERN Document Server

    Ahmed, Zeeshan; Guthrie, William; Quintavalle, John

    2016-01-01

    In recent years there has been considerable interest in developing photonic temperature sensors such as the Fiber Bragg gratings (FBG) as an alternative to resistance thermometry. In this study we examine the thermal response of FBGs over the temperature range of 233 K to 393 K. We demonstrate, in a hermetically sealed dry Argon environment, that FBG devices show a quadratic dependence on temperature with expanded uncertainties (k = 2) of ~500 mK. Our measurements indicate that the combined measurement uncertainty is dominated by uncertainty in determining the peak center fitting and by thermal aging of polyimide coated fibers.

  8. Fiber-optic liquid level monitoring system using microstructured polymer fiber Bragg grating array sensors: performance analysis

    DEFF Research Database (Denmark)

    Marques, C. A. F.; Pospori, A.; Saez-Rodriguez, D.;

    2015-01-01

    A highly sensitive liquid level monitoring system based on microstructured polymer optical fiber Bragg grating (mPOFBG) array sensors is reported for the first time. The configuration is based on five mPOFBGs inscribed in the same fiber in the 850 nm spectral region, showing the potential...... of the sensor is found to be 98 pm/cm of water, enhanced by more than a factor of 9 when compared to an equivalent sensor based on a silica fiber around 1550 nm. The temperature sensitivity is studied and a multi-sensor arrangement proposed, which has the potential to provide level readings independent...

  9. Miniature fiber Bragg grating sensor interrogator (FBG-Transceiver) system for use in aerospace and automotive health monitoring systems

    Science.gov (United States)

    Mendoza, Edgar A.; Kempen, Cornelia; Panahi, Allan; Lopatin, Craig

    2007-09-01

    Fiber Bragg grating sensors (FBGs) have gained rapid acceptance in aerospace and automotive structural health monitoring applications for the measurement of strain, stress, vibration, acoustics, acceleration, pressure, temperature, moisture, and corrosion distributed at multiple locations within the structure using a single fiber element. The most prominent advantages of FBGs are: small size and light weight, multiple FBG transducers on a single fiber, and immunity to radio frequency interference. A major disadvantage of FBG technology is that conventional state-of-the-art fiber Bragg grating interrogation systems are typically bulky and heavy bench top instruments that are assembled from off-the-shelf fiber optic and optical components integrated with a signal electronics board into an instrument console. Based on the need for a compact FBG interrogation system, this paper describes recent progress towards the development of a miniature fiber Bragg grating sensor interrogator (FBG-Transceiver TM) system based on multi-channel integrated optic sensor (InOSense) microchip technology. The hybrid InOSense microchip technology enables the integration of all of the functionalities, both passive and active, of conventional bench top FBG sensor interrogators systems, packaged in a miniaturized, low power operation, 2-cm x 5-cm small form factor (SFF) package suitable for the long-term structural health monitoring in applications where size, weight, and power are critical for operation. The sponsor of this program is NAVAIR under a DOD SBIR contract.

  10. Using a Fiber Loop and Fiber Bragg Grating as a Fiber Optic Sensor to Simultaneously Measure Temperature and Displacement

    Science.gov (United States)

    Chang, Yao-Tang; Yen, Chih-Ta; Wu, Yue-Shiun; Cheng, Hsu-Chih

    2013-01-01

    This study integrated a fiber loop manufactured by using commercial fiber (SMF-28, Corning) and a fiber Bragg grating (FBG) to form a fiber optic sensor that could simultaneously measure displacement and temperature. The fiber loop was placed in a thermoelectric cooling module with FBG affixed to the module, and, consequently, the center wavelength displacement of FBG was limited by only the effects of temperature change. Displacement and temperature were determined by measuring changes in the transmission of optical power and shifts in Bragg wavelength. This study provides a simple and economical method to measure displacement and temperature simultaneously. PMID:23681094

  11. Using a Fiber Loop and Fiber Bragg Grating as a Fiber Optic Sensor to Simultaneously Measure Temperature and Displacement

    Directory of Open Access Journals (Sweden)

    Hsu-Chih Cheng

    2013-05-01

    Full Text Available This study integrated a fiber loop manufactured by using commercial fiber (SMF-28, Corning and a fiber Bragg grating (FBG to form a fiber optic sensor that could simultaneously measure displacement and temperature. The fiber loop was placed in a thermoelectric cooling module with FBG affixed to the module, and, consequently, the center wavelength displacement of FBG was limited by only the effects of temperature change. Displacement and temperature were determined by measuring changes in the transmission of optical power and shifts in Bragg wavelength. This study provides a simple and economical method to measure displacement and temperature simultaneously.

  12. A Simple Fiber Bragg Grating-Based Sensor Network Architecture with Self-Protecting and Monitoring Functions

    Science.gov (United States)

    Yeh, Chien-Hung; Chow, Chi-Wai; Wu, Ping-Chun; Tseng, Fan-Gang

    2011-01-01

    A novel fiber Bragg grating (FBG)-based passive sensor architecture, which can be used to protect the fiber cut and monitor the multiple sensors simultaneously, is proposed and experimentally demonstrated. Here, we employ a wavelength-tunable erbium-doped fiber (EDF) laser scheme with 25 km cavity length acting as the detecting light source in central office (CO). Each FBG sensor, serving as a feedback element, is used in proposed sensor architecture. By tuning the tunable bandpass filter (TBF) placing inside cavity to match the corresponding Bragg wavelength of FBG over the amplification bandwidth, we can retrieve the related wavelength lasing for the FBG sensing and monitoring simultaneously. Moreover, the survivability and capacity of the passive FBG sensor architecture can be also enhanced. PMID:22319357

  13. High temperature strain sensor based on a fiber Bragg grating and rhombus metal structure.

    Science.gov (United States)

    Zhang, Liang; Liu, Yueming; Gao, Xiaoliang; Xia, Zhongcheng

    2015-10-01

    In this paper, a novel high temperature strain sensor based on a polyimide-coated fiber Bragg grating (FBG) and a rhombus metal structure is presented and experimentally demonstrated. By heating low softening point glass via a micro torch, the polyimide-coated FBG could be fixed into the rhombus metal structure. Consequently, when the rhombus structure is stretched and compressed, respectively, then the FBG will be subjected to a reverse state. Moreover, the strain sensitivity is controllable and enhanced by adjusting the dimension of the rhombus metal structure appropriately. The experiment was then carried out by using an equi-intensity cantilever beam and high temperature chamber, and the result showed that the proposed high temperature strain sensor could be used at the high temperature of 300°C. A resolution of ∼10  με has been experimentally achieved. The average wavelength strain sensitivity at 300°C is 1.821 and 1.814 pm/με, for the compressed and stretched states, respectively. PMID:26479639

  14. Life cycle strain monitoring in glass fibre reinforced polymer laminates using embedded fibre Bragg grating sensors from manufacturing to failure

    DEFF Research Database (Denmark)

    Nielsen, Michael Wenani; Schmidt, Jacob Wittrup; Høgh, Jacob Herold;

    2013-01-01

    failure. The internal process-induced strain development is investigated through use of different cure schedules and tool/part interactions. The fibre Bragg grating sensors successfully monitor resin flow front progression during infusion, and strain development during curing, representative...... of the different cure temperatures and tool/part interfaces used. Substantial internal process-induced strains develop in the transverse fibre direction, which should be taken into consideration when designing fibre-reinforced polymer laminates. Flexure tests indicate no significant difference in the mechanical......A holistic approach to strain monitoring in fibre-reinforced polymer composites is presented using embedded fibre Bragg grating sensors. Internal strains are monitored in unidirectional E-glass/epoxy laminate beams during vacuum infusion, curing, post-curing and subsequent loading in flexure until...

  15. Enhancement of the sensitivity of a temperature sensor based on Fiber Bragg Gratings via weak value amplification

    CERN Document Server

    Salazar-Serrano, L J; Amaya, W; Sales, S; Pruneri, V; Torres, J P

    2015-01-01

    We present a proof-of-concept experiment aimed at increasing the sensitivity of temperature sensors implemented with Fiber Bragg gratings by making use of a weak value amplification scheme. The technique requires only linear optics elements for its implementation, and appears as a promising method for extending the range of temperatures changes detectable to increasingly lower values than state-of the-art sensors can currently provide. The device implemented here is able to generate a shift of the centroid of the spectrum of a pulse of $\\mathrm{\\sim 0.035\\,nm/^{\\circ}C}$, a nearly fourfold increase in sensitivity over the same Fiber Bragg Grating system interrogated using standard methods.

  16. Smart Textile Based on Fiber Bragg Grating Sensors for Respiratory Monitoring: Design and Preliminary Trials.

    Science.gov (United States)

    Ciocchetti, Marco; Massaroni, Carlo; Saccomandi, Paola; Caponero, Michele A; Polimadei, Andrea; Formica, Domenico; Schena, Emiliano

    2015-09-14

    Continuous respiratory monitoring is important to assess adequate ventilation. We present a fiber optic-based smart textile for respiratory monitoring able to work during Magnetic Resonance (MR) examinations. The system is based on the conversion of chest wall movements into strain of two fiber Bragg grating (FBG) sensors, placed on the upper thorax (UT). FBGs are glued on the textile by an adhesive silicon rubber. To increase the system sensitivity, the FBGs positioning was led by preliminary experiments performed using an optoelectronic system: FBGs placed on the chest surface experienced the largest strain during breathing. System performances, in terms of respiratory period (TR), duration of inspiratory (TI) and expiratory (TE) phases, as well as left and right UT volumes, were assessed on four healthy volunteers. The comparison of results obtained by the proposed system and an optoelectronic plethysmography highlights the high accuracy in the estimation of TR, TI, and TE: Bland-Altman analysis shows mean of difference values lower than 0.045 s, 0.33 s, and 0.35 s for TR, TI, and TE, respectively. The mean difference of UT volumes between the two systems is about 8.3%. The promising results foster further development of the system to allow routine use during MR examinations.Continuous respiratory monitoring is important to assess adequate ventilation. We present a fiber optic-based smart textile for respiratory monitoring able to work during Magnetic Resonance (MR) examinations. The system is based on the conversion of chest wall movements into strain of two fiber Bragg grating (FBG) sensors, placed on the upper thorax (UT). FBGs are glued on the textile by an adhesive silicon rubber. To increase the system sensitivity, the FBGs positioning was led by preliminary experiments performed using an optoelectronic system: FBGs placed on the chest surface experienced the largest strain during breathing. System performances, in terms of respiratory period (TR

  17. Using a Fiber Loop and Fiber Bragg Grating as a Fiber Optic Sensor to Simultaneously Measure Temperature and Displacement

    OpenAIRE

    Hsu-Chih Cheng; Yue-Shiun Wu; Chih-Ta Yen; Yao-Tang Chang

    2013-01-01

    This study integrated a fiber loop manufactured by using commercial fiber (SMF-28, Corning) and a fiber Bragg grating (FBG) to form a fiber optic sensor that could simultaneously measure displacement and temperature. The fiber loop was placed in a thermoelectric cooling module with FBG affixed to the module, and, consequently, the center wavelength displacement of FBG was limited by only the effects of temperature change. Displacement and temperature were determined by measuring changes in th...

  18. Dual fiber Bragg gratings configuration-based fiber acoustic sensor for low-frequency signal detection

    Science.gov (United States)

    Yang, Dong; Wang, Shun; Lu, Ping; Liu, Deming

    2014-11-01

    We propose and fabricate a new type fiber acoustic sensor based on dual fiber Bragg gratings (FBGs) configuration. The acoustic sensor head is constructed by putting the sensing cells enclosed in an aluminum cylinder space built by two Cband FBGs and a titanium diaphragm of 50 um thickness. One end of each FBG is longitudinally adhered to the diaphragm by UV glue. Both of the two FBGs are employed for reflecting light. The dual FBGs play roles not only as signal transmission system but also as sensing component, and they demodulate each other's optical signal mutually during the measurement. Both of the two FBGs are pre-strained and the output optical power experiences fluctuation in a linear relationship along with a variation of axial strain and surrounding acoustic interference. So a precise approach to measure the frequency and sound pressure of the acoustic disturbance is achieved. Experiments are performed and results show that a relatively flat frequency response in a range from 200 Hz to 1 kHz with the average signal-to-noise ratio (SNR) above 21 dB is obtained. The maximum sound pressure sensitivity of 11.35mV/Pa is achieved with the Rsquared value of 0.99131 when the sound pressure in the range of 87.7-106.6dB. It has potential applications in low frequency signal detection. Owing to its direct self-demodulation method, the sensing system reveals the advantages of easy to demodulate, good temperature stability and measurement reliability. Besides, performance of the proposed sensor could be improved by optimizing the parameters of the sensor, especially the diaphragm.

  19. Advances in bio-tactile sensors for minimally invasive surgery using the fibre Bragg grating force sensor technique: a survey.

    Science.gov (United States)

    Abushagur, Abdulfatah A G; Arsad, Norhana; Reaz, Mamun Ibne; Bakar, A Ashrif A

    2014-04-09

    The large interest in utilising fibre Bragg grating (FBG) strain sensors for minimally invasive surgery (MIS) applications to replace conventional electrical tactile sensors has grown in the past few years. FBG strain sensors offer the advantages of optical fibre sensors, such as high sensitivity, immunity to electromagnetic noise, electrical passivity and chemical inertness, but are not limited by phase discontinuity or intensity fluctuations. FBG sensors feature a wavelength-encoding sensing signal that enables distributed sensing that utilises fewer connections. In addition, their flexibility and lightness allow easy insertion into needles and catheters, thus enabling localised measurements inside tissues and blood. Two types of FBG tactile sensors have been emphasised in the literature: single-point and array FBG tactile sensors. This paper describes the current design, development and research of the optical fibre tactile techniques that are based on FBGs to enhance the performance of MIS procedures in general. Providing MIS or microsurgery surgeons with accurate and precise measurements and control of the contact forces during tissues manipulation will benefit both surgeons and patients.

  20. High-sensitivity Cryogenic Temperature Sensors using Pressurized Fiber Bragg Gratings

    Science.gov (United States)

    Wu, Meng-Chou; DeHaven, Stanton L.

    2006-01-01

    Cryogenic temperature sensing was studied using a pressurized fiber Bragg grating (PFBG). The PFBG was obtained by simply applying a small diametric load to a regular fiber Bragg grating (FBG), which was coated with polyimide of a thickness of 11 micrometers. The Bragg wavelength of the PFBG was measured at temperatures from 295 to 4.2 K. A pressure-induced transition occurred at 200 K during the cooling cycle. As a result the temperature sensitivity of the PFBG was found to be nonlinear but reach 24 pm/K below 200 K, more than three times the regular FBG. For the temperature change from 80 K to 10 K, the PFBG has a total Bragg wavelength shift of about 470 pm, 10 times more than the regular FBG. From room temperature to liquid helium temperature the PFBG gives a total wavelength shift of 3.78 nm, compared to the FBG of 1.51 nm. The effect of the coating thickness on the temperature sensitivity of the gratings is also discussed.

  1. Fiber Bragg Grating Sensor Array System Based on Digital Phase Generated Carrier Demodulation and Reference Compensation Method

    Institute of Scientific and Technical Information of China (English)

    Jun He; Fang Li; Hao Xiao; Yu-Liang Liu

    2008-01-01

    A novel fiber Bragg grating (FBG) sensor array system based on digital phase generated carrier (PGC) demodulation and reference compensation method is proposed and set up. Experimental results confirm that the digital PGC demodulation can be used for wavelength-division-multiplexed FBG sensor array and the reference compensation method can reduce the environmental interference by approximately 40 dB in the frequency range from 20 Hz to 2 kHz. The minimum detectable wavelength-shift of the sensor system is 1×10-3 pm/Hz1/2.

  2. Effects of Coating and Diametric Load on Fiber Bragg Gratings as Cryogenic Temperature Sensors

    Science.gov (United States)

    Wu, meng-Chou; Pater, Ruth H.; DeHaven, Stanton L.

    2008-01-01

    Cryogenic temperature sensing was demonstrated using pressurized fiber Bragg gratings (PFBGs) with polymer coating of various thicknesses. The PFBG was obtained by applying a small diametric load to a regular fiber Bragg grating (FBG). The Bragg wavelengths of FBGs and PFBG were measured at temperatures from 295 K to 4.2 K. The temperature sensitivities of the FBGs were increased by the polymer coating. A physical model was developed to relate the Bragg wavelength shifts to the thermal expansion coefficients, Young's moduli, and thicknesses of the coating polymers. When a diametric load of no more than 15 N was applied to a FBG, a pressure-induced transition occurred at 200 K during the cooling cycle. The pressure induced transition yielded PFBG temperature sensitivities three times greater than conventional FBGs for temperatures ranging from 80 to 200 K, and ten times greater than conventional fibers for temperatures below 80 K. PFBGs were found to produce an increased Bragg wavelength shift of 2.2 nm compared to conventional FBGs over the temperature range of 4.2 to 300 K. This effect was independent of coating thickness and attributed to the change of the fiber thermo-optic coefficient.

  3. Sensitivity Enhancement for Fiber Bragg Grating Sensors by Four Wave Mixing

    Directory of Open Access Journals (Sweden)

    Jiangbing Du

    2015-04-01

    Full Text Available All-optical signal processing based on four wave mixing (FWM in a highly nonlinear fiber (HNLF to enhance the sensitivity of a fiber sensor is demonstrated and comprehensively reviewed in this paper. The principle is based on the frequency chirp magnification (FCM by FWM. Degenerated FWM, cascaded two-stage FWM and pump-pulsed FWM with optical parametric amplification (OPA are experimentally utilized for magnifying the frequency chirp. By using the pump pulse modulation to increase the peak power, OPA can be induced with the use of a dispersion-optimized HNLF. Therefore, ultra-highly efficient FWM can be realized due to the high peak power and OPA. By using the fiber Bragg grating (FBG laser as the FWM pump, the wavelength drift of the FBG can thus be magnified due to the FCM. We obtain a sensing performance of 13.3 pm/με strain sensitivity and 141.2 pm/°C temperature sensitivity for a conventional FBG, which has an intrinsic strain sensitivity of only ~1 pm/με and an intrinsic temperature sensitivity of only ~10 pm/°C, respectively.

  4. Smart Textile Based on Fiber Bragg Grating Sensors for Respiratory Monitoring: Design and Preliminary Trials

    Science.gov (United States)

    Ciocchetti, Marco; Massaroni, Carlo; Saccomandi, Paola; Caponero, Michele A.; Polimadei, Andrea; Formica, Domenico; Schena, Emiliano

    2015-01-01

    Continuous respiratory monitoring is important to assess adequate ventilation. We present a fiber optic-based smart textile for respiratory monitoring able to work during Magnetic Resonance (MR) examinations. The system is based on the conversion of chest wall movements into strain of two fiber Bragg grating (FBG) sensors, placed on the upper thorax (UT). FBGs are glued on the textile by an adhesive silicon rubber. To increase the system sensitivity, the FBGs positioning was led by preliminary experiments performed using an optoelectronic system: FBGs placed on the chest surface experienced the largest strain during breathing. System performances, in terms of respiratory period (TR), duration of inspiratory (TI) and expiratory (TE) phases, as well as left and right UT volumes, were assessed on four healthy volunteers. The comparison of results obtained by the proposed system and an optoelectronic plethysmography highlights the high accuracy in the estimation of TR, TI, and TE: Bland-Altman analysis shows mean of difference values lower than 0.045 s, 0.33 s, and 0.35 s for TR, TI, and TE, respectively. The mean difference of UT volumes between the two systems is about 8.3%. The promising results foster further development of the system to allow routine use during MR examinations. PMID:26389961

  5. Lamb wave sensing using fiber Bragg grating sensors for delamination detection in composite laminates

    Science.gov (United States)

    Takeda, N.; Okabe, Y.; Kuwahara, J.; Kojima, S.

    2005-05-01

    The authors are constructing a damage detection system using ultrasonic waves. In this system, a piezo-ceramic actuator generates Lamb waves in a CFRP laminate. After the waves propagate in the laminate, transmitted waves are received by a fiber Bragg grating (FBG) sensor attached on the laminate using a newly developed high-speed optical wavelength interrogation system. At first, the optimal gauge length of the FBG to detect ultrasonic waves was investigated through theoretical simulations and experiments. Then, the directional sensitivity of the FBG to ultrasonic waves was evaluated experimentally. On the basis of the above results, the 1mm FBG sensors were applied to the detection of Lamb waves propagated in carbon fiber reinforced plastic (CFRP) cross-ply laminates. The piezo-actuator was put on the laminate about 50mm away from the FBG sensor glued on the laminate, and three-cycle sine waves of 300kHz were excited repeatedly. The waveforms obtained by the FBG showed that S0 and A0 modes could be detected appropriately. Then, artificial delamination was made in the laminate by removing of a Teflon sheet embedded in the 0/90 interface after the manufacturing. When the Lamb waves passed through the delamination, the amplitude decreased and a new wave mode appeared. These phenomena could be well simulated using a finite element method. Furthermore, since the amplitude and the velocity of the new mode increased with an increase in the delamination length, this system has a potential to evaluate the interlaminar delamination length quantitatively.

  6. Tunable Polymer Fiber Bragg Grating (FBG) Inscription: Fabrication of Dual-FBG Temperature Compensated Polymer Optical Fiber Strain Sensors

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Stefani, Alessio; Bang, Ole

    2012-01-01

    We demonstrate stable wavelength tunable inscription of polymer optical fiber Bragg gratings (FBGs). By straining the fiber during FBG inscription, we linearly tune the center wavelength over 7 nm with less than 1% strain. Above 1% strain, the tuning curve saturates and we show a maximum tuning o...... of 12 nm with 2.25% strain. We use this inscription method to fabricate a dual-FBG strain sensor in a poly (methyl methacrylate) single-mode microstructured polymer optical fiber and demonstrate temperature compensated strain sensing around 850 nm.......We demonstrate stable wavelength tunable inscription of polymer optical fiber Bragg gratings (FBGs). By straining the fiber during FBG inscription, we linearly tune the center wavelength over 7 nm with less than 1% strain. Above 1% strain, the tuning curve saturates and we show a maximum tuning...

  7. A novel fiber-laser-based fiber Bragg grating strain sensor with high-birefringence Sagnac fiber loop mirror

    Institute of Scientific and Technical Information of China (English)

    Ou Xu; Shaohua Lu; Suchun Feng; Shuisheng Jian

    2008-01-01

    A novel fiber-laser-based strain sensor is proposed and experimentally demonstrated. The laser cavity is composed of a high-birefringence Sagnac fiber loop mirror (HiBi-SFLM) and a fiher Bragg grating (FBG) which also acts as a strain-sensing element. In the linear region of the HiBi-SFI,M reflection spectrum, when the strain applied on the FBG makes the Bragg grating wavelength shift,, the laser output power changes due to reflectivity variation of the HiBi-SFLM. Experimental results show that the laser output power varies ahnost linearly with the applied strain. The measurement of the output power can be performed by a conventional photo-detector.

  8. Post-Impact Fatigue Damage Monitoring Using Fiber Bragg Grating Sensors

    OpenAIRE

    Chow-Shing Shin; Shien-Kuei Liaw; Shi-Wei Yang

    2014-01-01

    It has been shown that impact damage to composite materials can be revealed by embedded Fiber Bragg Gratings (FBG) as a broadening and splitting of the latter’s characteristic narrow peak reflected spectrum. The current work further subjected the impact damaged composite to cyclic loading and found that the FBG spectrum gradually submerged into a rise of background intensity as internal damages progressed. By skipping the impact, directing the impact to positions away from the FBG and examin...

  9. A Fiber Bragg Grating Sensor Interrogation System Based on a Linearly Wavelength-Swept Thermo-Optic Laser Chip

    OpenAIRE

    Hyung-Seok Lee; Hwi Don Lee; Hyo Jin Kim; Jae Du Cho; Myung Yung Jeong; Chang-Seok Kim

    2014-01-01

    A linearized wavelength-swept thermo-optic laser chip was applied to demonstrate a fiber Bragg grating (FBG) sensor interrogation system. A broad tuning range of 11.8 nm was periodically obtained from the laser chip for a sweep rate of 16 Hz. To measure the linear time response of the reflection signal from the FBG sensor, a programmed driving signal was directly applied to the wavelength-swept laser chip. The linear wavelength response of the applied strain was clearly extracted with an R-sq...

  10. Micrometric Position Monitoring Using Fiber Bragg Grating Sensors in Silicon Detectors

    CERN Document Server

    Basile, E; Benussi, L; Bertani, M; Bianco, S; Caponero, M A; Colonna, D; Falco, F D; Fabbri, F L; Felli, F; Giardoni, M; La Monaca, A; Massa, F; Mensitieri, G; Ortenzi, B; Pallotta, M; Paolozzi, A; Passamonti, L; Pierluigi, D; Pucci, C; Russo, A; Saviano, G

    2005-01-01

    We show R&D results including long term stability, resolution, radiation hardness and characterization of Fiber Grating sensors used to monitor structure deformation, repositioning and surveying of silicon detector in High Energy Physics.

  11. A volatile-solvent gas fiber sensor based on polyaniline film coated on superstructure fiber Bragg gratings

    International Nuclear Information System (INIS)

    A fiber sensor based on a polyaniline (PANI) film that is coated on the surface of an etched superstructure fiber grating to detect volatile solvent vapors is experimentally demonstrated. This sensing mechanism is based on the interaction of the testing gas with the polyaniline coating film, which changes the film index, resulting in a shift in the Bragg wavelength. The sensitivity of this sensor to ammonia (NH3) gas is about 0.073 pm ppm−1, which depends on the optical characteristics of the fiber grating, the diameter of the fiber cladding and the constituents of the sensing film. Methanol concentrations can also be measured using this sensing scheme. The sensitivity of this sensor must be improved to provide a simple, reliable, repeatable and non-destructive method for sensing various chemical gases. (technical design note)

  12. Fiber Optic Sensors for Health Monitoring of Morphing Airframes. Part 2; Chemical Sensing Using Optical Fibers with Bragg Gratings

    Science.gov (United States)

    Wood, Karen; Brown, Timothy; Rogowski, Robert; Jensen, Brian

    2000-01-01

    Part 1 of this two part series described the fabrication and calibration of Bragg gratings written into a single mode optical fiber for use in strain and temperature monitoring. Part 2 of the series describes the use of identical fibers and additional multimode fibers, both with and without Bragg gratings, to perform near infrared spectroscopy. The demodulation system being developed at NASA Langley Research Center currently requires the use of a single mode optical fiber. Attempts to use this single mode fiber for spectroscopic analysis are problematic given its small core diameter, resulting in low signal intensity. Nonetheless, we have conducted a preliminary investigation using a single mode fiber in conjunction with an infrared spectrometer to obtain spectra of a high-performance epoxy resin system. Spectra were obtained using single mode fibers that contained Bragg gratings; however, the peaks of interest were barely discernible above the noise. The goal of this research is to provide a multipurpose sensor in a single optical fiber capable of measuring a variety of chemical and physical properties.

  13. Fiber Bragg Grating Sensor to Monitor Stress Kinetics in Drying Process of Commercial Latex Paints

    Directory of Open Access Journals (Sweden)

    Ivo de Lourenço

    2010-05-01

    Full Text Available In this paper, we report a study about the application of packaged fiber Bragg gratings used as strain sensors to monitor the stress kinetics during the drying process of commercial latex paints. Three stages of drying with distinct mechanical deformation and temporal behaviors were identified for the samples, with mechanical deformation from 15 μm to 21 μm in the longitudinal film dimension on time intervals from 370 to 600 minutes. Drying time tests based on human sense technique described by the Brazilian Technical Standards NBR 9558 were also done. The results obtained shows that human sense technique has a limited perception of the drying process and that the optical measurement system proposed can be used to characterize correctly the dry-through stage of paint. The influence of solvent (water addition in the drying process was also investigated. The paint was diluted with four parts paint and one part water (80% paint, and one part paint and one part water (50% paint. It was observed that the increase of the water ratio mixed into the paint decreases both the mechanical deformation magnitude and the paint dry-through time. Contraction of 5.2 μm and 10.4 μm were measured for concentrations of 50% and 80% of paint in the mixture, respectively. For both diluted paints the dry-through time was approximately 170 minutes less than undiluted paint. The optical technique proposed in this work can contribute to the development of new standards to specify the drying time of paint coatings.

  14. Sensitivity-Improved Strain Sensor over a Large Range of Temperatures Using an Etched and Regenerated Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Yupeng Wang

    2014-10-01

    Full Text Available A sensitivity-improved fiber-optic strain sensor using an etched and regenerated fiber Bragg grating (ER-FBG suitable for a large range of temperature measurements has been proposed and experimentally demonstrated. The process of chemical etching (from 125 µm to 60 µm provides regenerated gratings (at a temperature of 680 °C with a stronger reflective intensity (from 43.7% to 69.8%, together with an improved and linear strain sensitivity (from 0.9 pm/με to 4.5 pm/με over a large temperature range (from room temperature to 800 °C, making it a useful strain sensor for high temperature environments.

  15. Properties of Specialist Fibres and Bragg Gratings for Optical Fiber Sensors

    Directory of Open Access Journals (Sweden)

    John Canning

    2009-01-01

    Full Text Available The advent of optical fibres based on air holes running along their entirety opens up new directions in addressing various properties relevant to sensing, including the temperature/strain challenge of optical fibre sensors. This paper looks at the measurement challenges associated with temperature and strain, examines the potentially unique functionality structured fibre designs with and without gratings open up, and briefly describes some current research directions within conventional fibre and grating technologies.

  16. Deformation reconstruction of a smart Geogrid embedded with fiber Bragg grating sensors

    Science.gov (United States)

    Wang, Zheng-fang; Wang, Jing; Sui, Qing-mei; Jia, Lei; Li, Shu-cai; Liang, Xun-mei; Lu, Shi-de

    2015-12-01

    Due to the disadvantages of the current smart Geogrid for geotechnical use only being able measure strain and evaluate load location, a smart Geogrid embedded with fiber Bragg grating (FBG) sensors has been developed. Also, a deformation reconstruction technique has been investigated, which enables the newly designed smart Geogrid to evaluate the deformation fields of the key areas in geotechnical structures. After the fabricating process of the FBG embedded smart Geogrid was briefly introduced, a curvature information based deformation reconstruction method for the smart Geogrid was detailed. In order to optimize the distribution of the FBG nodes in the smart Geogrid, the finite element (FE) simulation data of the three possible causes of deformation were extracted, and the reconstruction results of the four distributions were compared. The results indicated that equidistantly distributed FBG sensors at the ribs of the smart Geogrid were the optimal distribution for the newly designed smart Geogrid. In addition, a modified deformation reconstruction technique was proposed to reduce reconstruction errors due to the stress concentration on the junctions of the smart Geogrid. The modified method, which employs FBG measured strains for calculating the deformation of the ribs and weighted strains to compute the coordinates of the two junctions, was validated by FE simulations. The simulation results illustrated that the modified method can improve the deformation reconstruction accuracy for both a Geogrid embedded with one fiber optic cable into one warp thread and a Geogrid embedded with multiple fiber optic cables in different warp threads. For the purpose of verifying the feasibility of the deformation measurements for the designed smart Geogrid using the proposed reconstruction techniques, experiments for the smart Geogrid embedded with one fiber optic cable were conducted in constant temperature environments. The curvatures of the smart Geogrid were calibrated

  17. Using maximum spectrum of continuous wavelet transform for demodulation of an overlapped spectrum in a fiber Bragg grating sensor network.

    Science.gov (United States)

    Hu, Ying; Mo, Wenqin; Dong, Kaifeng; Jin, Fang; Song, Junlei

    2016-06-10

    The maximum spectrum of the continuous wavelet transform (MSCWT) is proposed to demodulate the central wavelengths for the overlapped spectrum in a serial fiber Bragg grating (FBG) sensing system. We describe the operation principle of the MSCWT method. Moreover, the influence of the interval gap between two FBG wavelengths, 3 dB bandwidths, and optical powers of the reflected spectra are discussed. The simulation and experimental results indicate that the MSCWT can resolve an overlapped spectrum and decode the central wavelength with high accuracy. More importantly, the proposed peak detection method can enhance the sensing capacity of a wavelength division multiplexing FBG sensor network. PMID:27409024

  18. Strain Measurement Using Embedded Fiber Bragg Grating Sensors Inside an Anchored Carbon Fiber Polymer Reinforcement Prestressing Rod for Structural Monitoring

    DEFF Research Database (Denmark)

    Kerrouche, Abdelfateh; Boyle, William J.O.; Sun, Tong;

    2009-01-01

    Results are reported from a study carried out using a series of Bragg grating based optical fiber sensors written into a very short length (60mm) optical fiber net work and integrated into carbon fiber polymer reinforcement (CFPR) rod. Such rods are used as reinforcements in concrete structures...... from the calibrated force applied by the pulling machine and from a conventional resistive strain gauge mounted on the rod itself is obtained. Calculations from strain to shear stress show a relatively uniform stress distribution along the bar anchor used. The results give confidence to results from...

  19. Temperature insensitive hysteresis free highly sensitive polymer optical fiber Bragg grating humidity sensor.

    Science.gov (United States)

    Woyessa, Getinet; Nielsen, Kristian; Stefani, Alessio; Markos, Christos; Bang, Ole

    2016-01-25

    The effect of humidity on annealing of poly (methyl methacrylate) (PMMA) based microstructured polymer optical fiber Bragg gratings (mPOFBGs) and the resulting humidity responsivity are investigated. Typically annealing of PMMA POFs is done in an oven without humidity control around 80°C and therefore at low humidity. We demonstrate that annealing at high humidity and high temperature improves the performances of mPOFBGs in terms of stability and sensitivity to humidity. PMMA POFBGs that are not annealed or annealed at low humidity level will have a low and highly temperature dependent sensitivity and a high hysteresis in the humidity response, in particular when operated at high temperature. PMMA mPOFBGs annealed at high humidity show higher and more linear humidity sensitivity with negligible hysteresis. We also report how annealing at high humidity can blue-shift the FBG wavelength more than 230 nm without loss in the grating strength. PMID:26832503

  20. Fiber Optic Fabry-Perot Current Sensor Integrated with Magnetic Fluid Using a Fiber Bragg Grating Demodulation

    Directory of Open Access Journals (Sweden)

    Ji Xia

    2015-07-01

    Full Text Available An optical fiber current sensor based on Fabry-Perot interferometer using a fiber Bragg grating demodulation is proposed. Magnetic fluid is used as a sensitive medium in fiber optical Fabry-Perot (F-P cavity for the optical characteristic of magnetic-controlled refractive index. A Fiber Bragg grating (FBG is connected after the F-P interferometer which is used to reflect the optical power at the Bragg wavelength of the interference transmission spectrum. The corresponding reflective power of the FBG will change with different external current intensity, due to the shift on the interference spectrum of the F-P interferometer. The sensing probe has the advantages of convenient measurement for its demodulation, low cost and high current measurement accuracy on account of its sensing structure. Experimental results show that an optimal sensitivity of 0.8522 nw/A and measurement resolution of 0.001 A is obtained with a FBG at 1550 nm with 99% reflectivity.

  1. Optical fibres sensor based in the intensity switch of a linear laser with two Bragg gratings; Sensor de fibra optica basado en el salto de intensidad de un laser lineal con dos rejillas de Bragg

    Energy Technology Data Exchange (ETDEWEB)

    Basurto P, M.A.; Kuzin, E.A.; Archundia B, C.; Marroquin, E.; May A, M.; Cerecedo N, H.H.; Sanchez M, J.J. [Departamento de Fotonica y Fisica Optica, Instituto Nacional de Astrofisica, Optica y Electronica (INAOE). Apartado Postal 51 y 216, 72000 Puebla (Mexico); Tentori S, D.; Marquez B, I.; Shliagin, M.; Miridonov, S. [Centro de Investigacion CESE (Mexico)

    2000-07-01

    In this work we propose a new configuration for an optical fiber temperature sensor, based on a linear type Er-doped fiber laser. The laser cavity consists of an Er-doped fiber and two identical Bragg gratings at the fiber ends (working as reflectors). Temperature changes are detected by measuring, through one of the gratings, the intensity variations atthe system's output. When the temperature of one of the Bragg gratings is modified, a wavelength shift of its spectral reflectivity is observed. Hence, the laser emission intensity of the system is modified. We present experimental results of the intensity switch observed when the temperature difference between the gratings detunes their spectral reflectance. Making use of this effect it is possible to develop limit comparators to bound the temperature range for the object under supervision. This limiting work can be performed with a high sensitivity using a very simple interrogation procedure. (Author)

  2. Feedforward Neural Network for Force Coding of an MRI-Compatible Tactile Sensor Array Based on Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Paola Saccomandi

    2015-01-01

    Full Text Available This work shows the development and characterization of a fiber optic tactile sensor based on Fiber Bragg Grating (FBG technology. The sensor is a 3 × 3 array of FBGs encapsulated in a PDMS compliant polymer. The strain experienced by each FBG is transduced into a Bragg wavelength shift and the inverse characteristics of the sensor were computed by means of a feedforward neural network. A 21 mN RMSE error was achieved in estimating the force over the 8 N experimented load range while including all probing sites in the neural network training procedure, whereas the median force RMSE was 199 mN across the 200 instances of a Monte Carlo randomized selection of experimental sessions to evaluate the calibration under generalized probing conditions. The static metrological properties and the possibility to fabricate sensors with relatively high spatial resolution make the proposed design attractive for the sensorization of robotic hands. Furthermore, the proved MRI-compatibility of the sensor opens other application scenarios, such as the possibility to employ the array for force measurement during functional MRI-measured brain activation.

  3. A novel fiber Bragg grating pressure sensor with the smart metal structure based on the planar diaphragm

    Science.gov (United States)

    Guo, Ming-jin; Liang, Lei

    2010-10-01

    This study develops a novel fiber Bragg grating (FBG) pressure sensor encapsulated with the smart metal structure. The smart metal structure sensor made of welding the FBG plating a gold coat and the nickel tube together using Au-Ge solder is introduced, and the FBG is mounted on a planar diaphragm to enhance the pressure sensitivity. The diaphragm can be pressurized along one axial direction, and responds to an axial force only. The FBG sensor pressure sensitivity is derived theoretically and validated experimentally. The measured pressure sensitivity of the shift in the Bragg wavelength of our experimental sensor is about 1.68×10-4MPa-1, which is approximately 85 times higher than that can be achieved with a bare FBG. The pressure measurement precision of 0.5% over a full measurement range of 20 MPa has been achieved. The linearity of our sensor is also good, and there is almost no hysteresis effect. The temperature compensation performance of the pressure sensor is also studied.

  4. A Fiber Bragg Grating Sensor Interrogation System Based on a Linearly Wavelength-Swept Thermo-Optic Laser Chip

    Science.gov (United States)

    Lee, Hyung-Seok; Lee, Hwi Don; Kim, Hyo Jin; Cho, Jae Du; Jeong, Myung Yung; Kim, Chang-Seok

    2014-01-01

    A linearized wavelength-swept thermo-optic laser chip was applied to demonstrate a fiber Bragg grating (FBG) sensor interrogation system. A broad tuning range of 11.8 nm was periodically obtained from the laser chip for a sweep rate of 16 Hz. To measure the linear time response of the reflection signal from the FBG sensor, a programmed driving signal was directly applied to the wavelength-swept laser chip. The linear wavelength response of the applied strain was clearly extracted with an R-squared value of 0.99994. To test the feasibility of the system for dynamic measurements, the dynamic strain was successfully interrogated with a repetition rate of 0.2 Hz by using this FBG sensor interrogation system. PMID:25177803

  5. A Fiber Bragg Grating Sensor Interrogation System Based on a Linearly Wavelength-Swept Thermo-Optic Laser Chip

    Directory of Open Access Journals (Sweden)

    Hyung-Seok Lee

    2014-08-01

    Full Text Available A linearized wavelength-swept thermo-optic laser chip was applied to demonstrate a fiber Bragg grating (FBG sensor interrogation system. A broad tuning range of 11.8 nm was periodically obtained from the laser chip for a sweep rate of 16 Hz. To measure the linear time response of the reflection signal from the FBG sensor, a programmed driving signal was directly applied to the wavelength-swept laser chip. The linear wavelength response of the applied strain was clearly extracted with an R-squared value of 0.99994. To test the feasibility of the system for dynamic measurements, the dynamic strain was successfully interrogated with a repetition rate of 0.2 Hz by using this FBG sensor interrogation system.

  6. Crack Detection in Fibre Reinforced Plastic Structures Using Embedded Fibre Bragg Grating Sensors: Theory, Model Development and Experimental Validation

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    properties. When applying this concept to different structures, sensor systems and damage types, a combination of damage mechanics, monitoring technology, and modelling is required. The primary objective of this article is to demonstrate such a combination. This article is divided in three main topics......In a fibre-reinforced polymer (FRP) structure designed using the emerging damage tolerance and structural health monitoring philosophy, sensors and models that describe crack propagation will enable a structure to operate despite the presence of damage by fully exploiting the material’s mechanical...... a crack growth/damage event in fibre-reinforced polymer or structural adhesive-bonded structures using embedded fibre Bragg grating (FBG) sensors is presented by combining conventional measured parameters, such as wavelength shift, with parameters associated with measurement errors, typically ignored...

  7. Liquid level and temperature sensor based on an asymmetrical fiber Mach-Zehnder interferometer combined with a fiber Bragg grating

    Science.gov (United States)

    Li, Chao; Ning, Tigang; Zhang, Chan; Wen, Xiaodong; Li, Jing; Zhang, Chuanbiao

    2016-08-01

    A fiber optic sensor capable of simultaneous measurement of liquid level and temperature is proposed and demonstrated. The sensor is formed by the integration of an asymmetrical fiber Mach-Zehnder interferometer (aFMZI) with a fiber Bragg grating (FBG). The aFMZI was realized by concatenating a fiber taper and a lateral-shifted junction. By using the temperature sensing property of FBG, the liquid level sensor with dynamic temperature compensation can be achieved. For 10 pm wavelength resolution, a resolution of 0.15 cm in liquid level and 1.01 °C in temperature can be achieved. The prototype has the advantages of low fabrication cost and temperature compensated, which are desirable features in liquid level measurement.

  8. Interrogation of a linearly chirped fiber Bragg grating sensor with high resolution using a linearly chirped optical waveform.

    Science.gov (United States)

    Wang, Yiping; Zhang, Jiejun; Coutinho, Olympio; Yao, Jianping

    2015-11-01

    An approach to the interrogation of a linearly chirped fiber Bragg grating (LCFBG) sensor using a linearly frequency-modulated (or chirped) optical waveform (LFMOW) with a high resolution is proposed and experimentally demonstrated. An LFMOW is generated at a laser diode through linear frequency modulation. The generated LFMOW is then launched into an LCFBG pair consisting of two identical LCFBGs, with one serving as a sensing LCFBG and the other as a reference LCFBG. The reflection of the LFMOW from the two LCFBGs would lead to two time delayed LFMOWs. By beating the LFMOWs at a photodetector, a microwave signal with a beat frequency that is proportional to the time delay difference between the two reflected LFMOWs is generated. By measuring the frequency change of the beat signal, the strain applied to the sensing LCFBG is estimated. The proposed approach is experimentally evaluated. An LCFBG sensor with a resolution of 0.25 με is experimentally demonstrated. PMID:26512484

  9. Embedded fiber Bragg grating sensors for true temperature monitoring in Nb3Sn superconducting magnets for high energy physics

    Science.gov (United States)

    Chiuchiolo, A.; Bajas, H.; Bajko, M.; Consales, M.; Giordano, M.; Perez, J. C.; Cusano, A.

    2016-05-01

    The luminosity upgrade of the Large Hadron Collider (HL-LHC) planned at the European Organization for Nuclear Research (CERN) requires the development of a new generation of superconducting magnets based on Nb3Sn technology. The instrumentation required for the racetrack coils needs the development of reliable sensing systems able to monitor the magnet thermo-mechanical behavior during its service life, from the coil fabrication to the magnet operation. With this purpose, Fiber Bragg Grating (FBG) sensors have been embedded in the coils of the Short Model Coil (SMC) magnet fabricated at CERN. The FBG sensitivity to both temperature and strain required the development of a solution able to separate mechanical and temperature effects. This work presents for the first time a feasibility study devoted to the implementation of an embedded FBG sensor for the measurement of the "true" temperature in the impregnated Nb3Sn coil during the fabrication process.

  10. Comparative Study of Fiber Bragg Gratings and Fiber Polarimetric Sensors for Structural Health Monitoring of Carbon Composites

    Directory of Open Access Journals (Sweden)

    Massimo Olivero

    2014-01-01

    Full Text Available A comparative study is presented between Bragg grating (FBG and polarimetric sensors (PS, two of the most promising fiber optic sensing techniques for the structural health monitoring of smart materials based on carbon fiber composites. The paper describes the realization of a test plate equipped with both types of sensors and reports the characterization under static and dynamic conditions, highlighting pros and cons of both technologies. The FBG setup achieves 1.15 ± 0.0016 pm/kg static load response and reproduces dynamic excitation with 0.1% frequency uncertainty; the PS system exhibits a sensitivity of 1.74 ± 0.001 mV/kg and reproduces dynamic excitation with 0.5% frequency uncertainty. It is shown that the PS technology is a good and cheap alternative to FBG for vibration-monitoring of small structures at high frequency.

  11. Interrogation of a linearly chirped fiber Bragg grating sensor with high resolution using a linearly chirped optical waveform.

    Science.gov (United States)

    Wang, Yiping; Zhang, Jiejun; Coutinho, Olympio; Yao, Jianping

    2015-11-01

    An approach to the interrogation of a linearly chirped fiber Bragg grating (LCFBG) sensor using a linearly frequency-modulated (or chirped) optical waveform (LFMOW) with a high resolution is proposed and experimentally demonstrated. An LFMOW is generated at a laser diode through linear frequency modulation. The generated LFMOW is then launched into an LCFBG pair consisting of two identical LCFBGs, with one serving as a sensing LCFBG and the other as a reference LCFBG. The reflection of the LFMOW from the two LCFBGs would lead to two time delayed LFMOWs. By beating the LFMOWs at a photodetector, a microwave signal with a beat frequency that is proportional to the time delay difference between the two reflected LFMOWs is generated. By measuring the frequency change of the beat signal, the strain applied to the sensing LCFBG is estimated. The proposed approach is experimentally evaluated. An LCFBG sensor with a resolution of 0.25 με is experimentally demonstrated.

  12. Fuel level sensor based on polymer optical fiber Bragg gratings for aircraft applications

    DEFF Research Database (Denmark)

    Marques, C. A. F.; Pospori, A.; Sáez-Rodríguez, D.;

    2016-01-01

    Safety in civil aviation is increasingly important due to the increase in flight routes and their more challenging nature. Like other important systems in aircraft, fuel level monitoring is always a technical challenge. The most frequently used level sensors in aircraft fuel systems are based...... and present many advantages for aircraft fuel measurement. Different OFLLSs have been developed, such as the pressure type, float type, optical radar type, TIR type and side-leaking type. Amongst these, many types of OFLLSs based on fiber gratings have been demonstrated. However, these sensors have not been...... previously published in the literature, making it a potentially useful tool for aircraft fuel monitoring....

  13. Trends and future of fiber Bragg grating sensing technologies: tailored draw tower gratings (DTGs)

    Science.gov (United States)

    Lindner, E.; Hartung, A.; Hoh, D.; Chojetzki, C.; Schuster, K.; Bierlich, J.; Rothhardt, M.

    2014-05-01

    Today fiber Bragg gratings are commonly used in sensing technology as well as in telecommunications. Numerous requirements must be satisfied for their application as a sensor such as the number of sensors per system, the measurement resolution and repeatability, the sensor reusability as well as the sensor costs. In addition current challenges need to be met in the near future for sensing fibers to keep and extend their marketability such as the suitability for sterilization, hydrogen darkening or the separation of strain and temperature (or pressure and temperature). In this contribution we will give an outlook about trends and future of the fiber Bragg gratings in sensing technologies. Specifically, we will discuss how the use of draw tower grating technology enables the production of tailored Bragg grating sensing fibers, and we will present a method of separating strain and temperature by the use of a single Bragg grating only, avoiding the need for additional sensors to realize the commonly applied temperature compensation.

  14. Thermal Expansion Measurements in Fresh and Saline Ice Using Fiber Optic Strain Gauges and Multipoint Temperature Sensors Based on Bragg Gratings

    OpenAIRE

    Aleksey Marchenko; Ben Lishman; David Wrangborg; Torsten Thiel

    2016-01-01

    This paper describes the use of Fiber Bragg Grating (FBG) sensors to investigate the thermomechanical properties of saline ice. FBG sensors allowed laboratory measurements of thermal expansion of ice samples with a range of different sizes and geometries. The high sampling frequency, accuracy, and resolution of the FBG sensors provide good quality data across a temperature range from 0°C to −20°C. Negative values of the effective coefficient of thermal expansion were observed in ice samples w...

  15. The capability of fiber Bragg grating sensors to measure amputees' trans-tibial stump/socket interface pressures.

    Science.gov (United States)

    Al-Fakih, Ebrahim A; Osman, Noor Azuan Abu; Eshraghi, Arezoo; Adikan, Faisal Rafiq Mahamd

    2013-08-12

    This study presents the first investigation into the capability of fiber Bragg grating (FBG) sensors to measure interface pressure between the stump and the prosthetic sockets of a trans-tibial amputee. FBG element(s) were recoated with and embedded in a thin layer of epoxy material to form a sensing pad, which was in turn embedded in a silicone polymer material to form a pressure sensor. The sensor was tested in real time by inserting a heavy-duty balloon into the socket and inflating it by using an air compressor. This test was conducted to examine the sensitivity and repeatability of the sensor when subjected to pressure from the stump of the trans-tibial amputee and to mimic the actual environment of the amputee's Patellar Tendon (PT) bar. The sensor exhibited a sensitivity of 127 pm/N and a maximum FSO hysteresis of around ~0.09 in real-time operation. Very good reliability was achieved when the sensor was utilized for in situ measurements. This study may lead to smart FBG-based amputee stump/socket structures for pressure monitoring in amputee socket systems, which will result in better-designed prosthetic sockets that ensure improved patient satisfaction.

  16. The Capability of Fiber Bragg Grating Sensors to Measure Amputees’ Trans-Tibial Stump/Socket Interface Pressures

    Directory of Open Access Journals (Sweden)

    Faisal Rafiq Mahamd Adikan

    2013-08-01

    Full Text Available This study presents the first investigation into the capability of fiber Bragg grating (FBG sensors to measure interface pressure between the stump and the prosthetic sockets of a trans-tibial amputee. FBG element(s were recoated with and embedded in a thin layer of epoxy material to form a sensing pad, which was in turn embedded in a silicone polymer material to form a pressure sensor. The sensor was tested in real time by inserting a heavy-duty balloon into the socket and inflating it by using an air compressor. This test was conducted to examine the sensitivity and repeatability of the sensor when subjected to pressure from the stump of the trans-tibial amputee and to mimic the actual environment of the amputee’s Patellar Tendon (PT bar. The sensor exhibited a sensitivity of 127 pm/N and a maximum FSO hysteresis of around ~0.09 in real-time operation. Very good reliability was achieved when the sensor was utilized for in situ measurements. This study may lead to smart FBG-based amputee stump/socket structures for pressure monitoring in amputee socket systems, which will result in better-designed prosthetic sockets that ensure improved patient satisfaction.

  17. Inverse problem of determining periodic surface profile oscillation defects of steel materials with a fiber Bragg grating sensor.

    Science.gov (United States)

    Cięszczyk, Sławomir; Kisała, Piotr

    2016-02-20

    We propose and experimentally demonstrate a method for the detection of steel material defects utilizing a fiber Bragg grating sensor. The considered defects are periodic grooves along the length of the tested steel profile. Direct measurement of the spectral reflectance characteristics of the fiber is performed, and the related inverse problem of indirect defect shape determination is solved. It has been demonstrated that the defect periodicity estimation is 2.5 mm, with an error of less than 0.1. Furthermore, it has been shown that for periodic intervals of the order of 5 mm, the difference between the strain amplitude calculated using our method and the amplitude obtained via the finite element method was 1.4 mϵ. PMID:26906595

  18. In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement.

    Science.gov (United States)

    Sampath, Umesh; Kim, Hyunjin; Kim, Dae-gil; Kim, Young-Chon; Song, Minho

    2015-07-27

    A fiber-optic cure monitoring system is proposed to measure curing status of composite structure such as a large scale wind turbine blade. The monitoring is based on the measurement of Fresnel reflectivity at the optical fiber/epoxy resin interface. The refractive index of epoxy resin varies throughout curing stages, changing the Fresnel reflectivity. The curing status is decided by monitoring the reflected intensity variation. The usage of fiber Bragg grating (FBG) sensor helps to separate the temperature-induced cross effects. A Gaussian curve fitting algorithm was applied to FBG spectra which were distorted in curing procedure. The substantial measurement errors could be minimized by locating the centroids of the Gaussian curve-fitted spectra. From the experiments performed in various isothermal conditions, the proposed system successfully identified the onset of gelation and the completion of curing of epoxy resins.

  19. In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement

    Directory of Open Access Journals (Sweden)

    Umesh Sampath

    2015-07-01

    Full Text Available A fiber-optic cure monitoring system is proposed to measure curing status of composite structure such as a large scale wind turbine blade. The monitoring is based on the measurement of Fresnel reflectivity at the optical fiber/epoxy resin interface. The refractive index of epoxy resin varies throughout curing stages, changing the Fresnel reflectivity. The curing status is decided by monitoring the reflected intensity variation. The usage of fiber Bragg grating (FBG sensor helps to separate the temperature-induced cross effects. A Gaussian curve fitting algorithm was applied to FBG spectra which were distorted in curing procedure. The substantial measurement errors could be minimized by locating the centroids of the Gaussian curve-fitted spectra. From the experiments performed in various isothermal conditions, the proposed system successfully identified the onset of gelation and the completion of curing of epoxy resins.

  20. In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement.

    Science.gov (United States)

    Sampath, Umesh; Kim, Hyunjin; Kim, Dae-gil; Kim, Young-Chon; Song, Minho

    2015-01-01

    A fiber-optic cure monitoring system is proposed to measure curing status of composite structure such as a large scale wind turbine blade. The monitoring is based on the measurement of Fresnel reflectivity at the optical fiber/epoxy resin interface. The refractive index of epoxy resin varies throughout curing stages, changing the Fresnel reflectivity. The curing status is decided by monitoring the reflected intensity variation. The usage of fiber Bragg grating (FBG) sensor helps to separate the temperature-induced cross effects. A Gaussian curve fitting algorithm was applied to FBG spectra which were distorted in curing procedure. The substantial measurement errors could be minimized by locating the centroids of the Gaussian curve-fitted spectra. From the experiments performed in various isothermal conditions, the proposed system successfully identified the onset of gelation and the completion of curing of epoxy resins. PMID:26225970

  1. Fiber Bragg grating based tunable sensitivity goniometer

    Science.gov (United States)

    Padma, Srivani; Umesh, Sharath; Pant, Shweta; Srinivas, Talabattula; Asokan, Sundarrajan

    2016-03-01

    Goniometer has found extensive usage in diverse applications, primary being medical field in which it is employed for obtaining the range of motion of joints during physical therapy. It is imperative to have a dynamic system to measure the range of motion which will aid for a progressive therapeutic treatment. Hence in the present study, a novel goniometer for real time dynamic angle measurement between two surfaces with the aid of a Fiber Bragg Grating sensor is proposed. The angular rotation between the two surfaces will be identified by the two arms of the Fiber Bragg Grating Goniometer (FBGG), which is translated to the rotation of the shaft which holds these arms together. A cantilever beam is fixed onto the base plate whose free end is connected to the rotating shaft. The rotating shaft will actuate a mechanism which will pull the free end of the cantilever resulting in strain variation over the cantilever beam. The strain variation on the cantilever beam is measured by the Fiber Bragg Grating sensor bonded over it. Further, the proposed FBGG facilitates tunable sensitivity by the discs of varying diameters on the rotating shaft. Tunable sensitivity of the FBGG is realised by the movement of these discs by varying circumferential arc lengths for the same angular movement, which will actuate the pull on the cantilever beam. As per the requirement of the application in terms of resolution and range of angular measurement, individual mode of sensitivity may be selected.

  2. An expandable crosstalk reduction method for inline fiber Fabry–Pérot sensor array based on fiber Bragg gratings

    Science.gov (United States)

    Jiang, Peng; Ma, Lina; Hu, Zhengliang; Hu, Yongming

    2016-07-01

    The inline time division multiplexing (TDM) fiber Fabry–Pérot (FFP) sensor array based on fiber Bragg gratings (FBGs) is attractive for many applications. But the intrinsic multi-reflection (MR) induced crosstalk limits applications especially those needing high resolution. In this paper we proposed an expandable method for MR-induced crosstalk reduction. The method is based on complexing-exponent synthesis using the phase-generated carrier (PGC) scheme and the special common character of the impulse responses. The method could promote demodulation stability simultaneously with the reduction of MR-induced crosstalk. A polarization-maintaining 3-TDM experimental system with an FBG reflectivity of about 5 % was set up to validate the method. The experimental results showed that crosstalk reduction of 13 dB and 15 dB was achieved for sensor 2 and sensor 3 respectively when a signal was applied to the first sensor and crosstalk reduction of 8 dB was achieved for sensor 3 when a signal was applied to sensor 2. The demodulation stability of the applied signal was promoted as well. The standard deviations of the amplitude distributions of the demodulated signals were reduced from 0.0046 to 0.0021 for sensor 2 and from 0.0114 to 0.0044 for sensor 3. Because of the convenience of the linear operation of the complexing-exponent and according to the common character of the impulse response we found, the method can be effectively extended to the array with more TDM channels if the impulse response of the inline FFP sensor array with more TDM channels is derived. It offers potential to develop a low-crosstalk inline FFP sensor array using the PGC interrogation technique with relatively high reflectivity FBGs which can guarantee enough light power received by the photo-detector.

  3. A novel durable intelligent fiber reinforced polymer anchor with embedded optical fiber Bragg grating sensors

    Institute of Scientific and Technical Information of China (English)

    HUANG MingHua; ZHOU Zhi; YUE Shuai; HE JianPing; OU JinPing

    2012-01-01

    Anchors are the key members of the geotechnical anchorage engineering,it is urgent to monitor their behavior in service for preventing the potential risks.This paper proposes a novel durable intelligent fiber reinforced polymer (FRP) anchor to understand the behavior of the anchor in the field application.Series of optical fiber Bmgg grating (FBG) sensors were embedded into the central axis along the anchor to sense itself axial strain variations.An evolution model of axial strain was also developed to evaluate the behavior along the anchor.A demonstration test was carried out to test its self-sensing properties in the laboratory.The experimental results indicated that the embedded FBG sensors monitored the behavior,e.g.axial strain/interfacial damage evolutions along the anchor and displacement/applied load at the pulling end effectively,without influence from the interfacial compression and slip effects.

  4. Measurement of the thermal expansion of space structures using fiber Bragg grating sensors and displacement measuring interferometers

    International Nuclear Information System (INIS)

    A thermal deformation measurement system, composed of fiber Bragg grating (FBG) sensors for strain measurement and a displacement measuring interferometer (DMI) system for accurate specimen expansion data acquisition, was prepared and installed in a vacuum chamber where the temperature of the test specimen can be controlled to simulate space environments. The DMI system, which consists of two heterodyne interferometers, a laser head, electronics and a thermally stable specimen base made of fused silica, was used to validate the thermal expansions of the specimens measured by the FBG sensors. We measured the average coefficient of thermal expansion (CTE) of an Invar specimen, known as a thermally stable material, using both the FBG sensors and the DMI system in vacuum conditions from 20 °C to 40 °C. The CTE results of the Invar specimen were found to be 1.226 × 10−6 K−1 and 1.298 × 10−6 K−1 based on the FBG and DMI measurements, respectively. The present results show that it is possible to precisely measure the thermal deformation of a specimen or structure in space environments using FBG sensors

  5. Fibre Bragg Grating Components for Filtering, Switching and Lasing

    OpenAIRE

    Yu, Zhangwei

    2008-01-01

    Fibre Bragg gratings (FBGs) are key components for a vast number of applications in optical communication systems, microwave photonics systems, and optical sensors, etc. The main topic of this thesis is fibre Bragg grating fabrication and applications in direct microwave optical filtering, high speed switching and switchable dual-wavelength fibre lasers. First, a brief overview is given about the photosensitivity in optical fibre, basic FBG fabrication techniques, the popular coupled-mode the...

  6. 光纤布喇格光栅沉降传感器%Fiber Bragg Grating Settlement Sensors

    Institute of Scientific and Technical Information of China (English)

    杜磊; 龚元; 吴宇; 饶云江; 赵天

    2011-01-01

    According to the fiber Bragg gratings optical sensing principle,a novel structure of fiber Bragg settlement sensors are developed, based on a cantilever beam and a metal diaphragm. The sensing characteristics are investigated. In the experiment, water level differences to are used simulate foundation settlement. The experimental results indicate that sensitivity of -2. Llpm/mm and good linearity of higher than 0. 999 can be obtained. By changing the thickness and the effective length of cantilever beam, the measurement range and sensitivity of the sensor can be optimized to meet various applications. From the results,it is known that the sensor will play an important role in bridges,railways and other foundation settlement monitoring.%根据光纤布喇格光栅的光学传感原理,提出了一种基于悬臂梁及金属弹性膜片的光纤布喇格光栅沉降传感器结构,对其传感特性进行了实验研究.实验通过产生水的液位差来模拟地基沉降,分析结果显示,光纤布喇格光栅中心反射波长漂移对液位差呈现良好的线性关系,线性度高于0.999,灵敏度可达一2.11 pm/mm.通过改变悬臂梁厚度和有效长度,可以对传感器测量范围和灵敏度进行调整,以满足各种应用场合.综合实验结果,该传感器在桥梁、铁路地基等沉降监测方面具有重要意义.

  7. Design of copper/carbon-coated fiber Bragg grating acoustic sensor net for integrated health monitoring of nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Chong, See Yenn [Department of Aerospace Engineering, Chonbuk National University, 664-14 Duckjin-dong, Duckjin-gu, Jeonju, Chonbuk 561-756 (Korea, Republic of); Lee, Jung-Ryul, E-mail: leejrr@jbnu.ac.k [Department of Aerospace Engineering, Chonbuk National University, 664-14 Duckjin-dong, Duckjin-gu, Jeonju, Chonbuk 561-756 (Korea, Republic of); Yun, Chang-Yong [Department of Aerospace Engineering, Chonbuk National University, 664-14 Duckjin-dong, Duckjin-gu, Jeonju, Chonbuk 561-756 (Korea, Republic of); Sohn, Hoon [Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 335, Gwahangno, Yuseong-gu, Daejon 305-701 (Korea, Republic of)

    2011-05-15

    Research highlights: We develop a cost-effective fiber Bragg grating (FBG) acoustic sensor net for nuclear power plants using copper/carbon (Cu/C)-coated fiber. A chemical method is proposed to remove the Cu/C coating. A 5 mm FBG is successfully inscribed in a Ge-doped silica core through a 7 mm-long silica section with the coating removed. The Cu/C-coated fiber net shows good thermal resistance (<345 {sup o}C). The Cu/C-coated FBG sensor using the metallic adhesive successfully detects the acousto-ultrasonic waves generated by pencil lead breaking and laser beam excitation. - Abstract: A nuclear power plant (NPP) is a harsh environment that gives rise to age-related degradation of the plant structures, and eventually leads to radiation leakage that threatens humans. Integrated structural health monitoring (ISHM) technology is a strong candidate for the prevention of the NPP accidents during operation. Prior studies have shown that fiber Bragg gratings (FBGs) and metal-coated fibers have good radiation and high temperature resistance. In this study, a FBG acoustic sensor using a metallic adhesive for installation and a relatively economical copper/carbon (Cu/C)-coated fiber is developed for ISHM of high temperature NPP structures. A chemical method is proposed to remove the Cu/C coating. A 5 mm FBG was successfully inscribed in a Ge-doped silica core through a 7 mm-long silica section with the coating removed. The Cu/C-coated fiber with the same core/clad structure as the standard SMF allowed no-loss fusion splicing, and showed good adaptability to the economical standard fiber, adaptor, connector, and instruments. It showed also good thermal resistance (<345 {sup o}C) with no degradation in optical power during the optical transmission. The metallic adhesive used to install the FBG in a one-end-free configuration showed superior bonding reliability during temperature cycles ranging from 25 {sup o}C to 345 {sup o}C. The FBG reflectivity was stabilized at a 58% drop

  8. Fabrication and characterization of metal-packaged fiber Bragg grating sensor by one-step ultrasonic welding

    Science.gov (United States)

    Zhang, Yumin; Zhu, Lianqing; Luo, Fei; Dong, Mingli; Ding, Xiangdong; He, Wei

    2016-06-01

    A metallic packaging technique of fiber Bragg grating (FBG) sensors is developed for measurement of strain and temperature, and it can be simply achieved via one-step ultrasonic welding. The average strain transfer rate of the metal-packaged sensor is theoretically evaluated by a proposed model aiming at surface-bonded metallic packaging FBG. According to analytical results, the metallic packaging shows higher average strain transfer rate compared with traditional adhesive packaging under the same packaging conditions. Strain tests are performed on an elaborate uniform strength beam for both tensile and compressive strains; strain sensitivities of approximately 1.16 and 1.30 pm/μɛ are obtained for the tensile and compressive situations, respectively. Temperature rising and cooling tests are also executed from 50°C to 200°C, and the sensitivity of temperature is 36.59 pm/°C. All the measurements of strain and temperature exhibit good linearity and stability. These results demonstrate that the metal-packaged sensors can be successfully fabricated by one-step welding technique and provide great promise for long-term and high-precision structural health monitoring.

  9. Fiber Bragg grating fabrication for the implementation of sensors in the electronics and optoelectronics laboratory at BUAP

    Science.gov (United States)

    Bracamontes Rodríguez, Y. E.; Beltrán Pérez, G.; Castillo Mixcóatl, J.; Muñoz Aguirre, S.

    2011-09-01

    Fiber Bragg gratings (FBG) are important optical devices since they have been quite successful not only in the field of communications but also in sensor systems and optical fiber lasers. In the sensors area they are generally used as detection elements for different physical parameters such as temperature, strain, flow, etc. In the electronics and optoelectronics laboratory at Benemérita Universidad Autónoma de Puebla (LEyO-BUAP), there are already experimental setups of sensors as well as laser systems, where FBGs are fundamental elements for their adequate performance. However, these FBGs are commercial devices and they present limited characteristics in their transmission profiles, bandwidth and reflectivity. On the other hand, in some occasions, the delivery time from the fabricant to the customer is quite long. Therefore, it is important for LEyO to implement a system to fabricate this kind of devices, which would mean LEyO independence in the technological development. In this work, results of FBGs fabrication based on the phase mask technique are presented. Such mask is optimized for UV and it has a period of 1060 nm. A Nd:YAG pulsed laser with a 5 ns pulse length and an energy of 40 mJ was used as the UV source employing the 4th harmonic generation to obtain a 266 nm wavelength. Ge-doped fiber was used to fabricate the devices.

  10. On-line monitoring of multi-component strain development in a tufting needle using optical fibre Bragg grating sensors

    International Nuclear Information System (INIS)

    Dynamic loadings induced on a tufting needle during the tufting of dry carbon fibre preform via a commercial robot-controlled tufting head were investigated in situ and in real-time using optical fibre Bragg grating (FBG) sensors bonded to the needle shaft. The sensors were configured such that the axial strain and bending moments experienced by the needle could be measured. A study of the influence of thread and thread type on the strain imparted to the needle revealed axial strain profiles which had equivalent trends but different magnitudes. The mean of the maximum axial compression strains measured during the tufting of a 4-ply quasi-isotropic carbon fibre dry preform were − 499 ± 79 με, − 463 ± 51 με and − 431 ± 59 με for a needle without thread, with metal wire and with Kevlar® thread, respectively. The needle similarly exhibited bending moments of different magnitude when the different needle feeding configurations were used. (paper)

  11. Structural health monitoring of wind turbine blade using fiber Bragg grating sensors and fiber optic rotary joint

    Science.gov (United States)

    Chen, Y.; Ni, Y. Q.; Ye, X. W.; Yang, H. X.; Zhu, S.

    2012-04-01

    Wind energy utilization as a reliable energy source has become a large industry in the last 20 years. Nowadays, wind turbines can generate megawatts of power and have rotor diameters that are on the order of 100 meters in diameter. One of the key components in a wind turbine is the blade which could be damaged by moisture absorption, fatigue, wind gusts or lighting strikes. The wind turbine blades should be routinely monitored to improve safety, minimize downtime, lower the risk of sudden breakdowns and associated huge maintenance and logistics costs, and provide reliable power generation. In this paper, a real-time wind turbine blade monitoring system using fiber Bragg grating (FBG) sensors with the fiber optic rotary joint (FORJ) is proposed, and applied to monitor the structural responses of a 600 W small scale wind turbine. The feasibility and effectiveness of the FORJ is validated by continuously transmitting the optical signals between the FBG interrogator at the stationary side and the FBG sensors on the rotating part. A comparison study between the measured data from the proposed system and those from an IMote2-based wireless strain measurement system is conducted.

  12. Evaluation of debonding progress in composite bonded structures by ultrasonic wave sensing with fiber Bragg grating sensors

    Science.gov (United States)

    Okabe, Yoji; Kuwahara, Junichiro; Takeda, Nobuo; Ogisu, Toshimichi; Kojima, Seiji; Komatsuzaki, Shinji

    2006-03-01

    The authors are constructing a damage detection system using ultrasonic waves. In this system, a piezo-ceramic actuator generates ultrasonic waves in a carbon fiber reinforced plastic (CFRP) laminate. After the waves propagate in the laminate, transmitted waves are received by a fiber Bragg grating (FBG) sensor using a newly developed high-speed optical wavelength interrogation system. In this research, this system was applied to the evaluation of debonding progress in CFRP bonded structures. At first, small-diameter FBG sensors, whose cladding diameter is about 1/3 of common optical fibers, were embedded in an adhesive layer of a double-lap type coupon specimen consisting of CFRP quasi-isotropic laminates, and the ultrasonic wave was propagated through the debonded region. After that, the wavelet transform was applied to the received waveforms and the results showed clear difference depending on the debonding length. Hence, a new damage index was proposed, which could be obtained from the difference in the distribution of the wavelet transform coefficient. As a result, the damage index increased with an increase in the debonded area. Furthermore this system was applied to the skin/stringer structural element of airplanes made of CFRP laminates. Both of the waves received by a bonded FBG and by an embedded FBG changed sensitively to the debonding progress. Also, the damage index could evaluate the length of the debonding between the skin and the stringer.

  13. On-line monitoring of multi-component strain development in a tufting needle using optical fibre Bragg grating sensors

    Science.gov (United States)

    Chehura, Edmon; Dell'Anno, Giuseppe; Huet, Tristan; Staines, Stephen; James, Stephen W.; Partridge, Ivana K.; Tatam, Ralph P.

    2014-07-01

    Dynamic loadings induced on a tufting needle during the tufting of dry carbon fibre preform via a commercial robot-controlled tufting head were investigated in situ and in real-time using optical fibre Bragg grating (FBG) sensors bonded to the needle shaft. The sensors were configured such that the axial strain and bending moments experienced by the needle could be measured. A study of the influence of thread and thread type on the strain imparted to the needle revealed axial strain profiles which had equivalent trends but different magnitudes. The mean of the maximum axial compression strains measured during the tufting of a 4-ply quasi-isotropic carbon fibre dry preform were - 499 ± 79 μɛ, - 463 ± 51 μɛ and - 431 ± 59 μɛ for a needle without thread, with metal wire and with Kevlar® thread, respectively. The needle similarly exhibited bending moments of different magnitude when the different needle feeding configurations were used.

  14. Dynamic Strain Measurements on Automotive and Aeronautic Composite Components by Means of Embedded Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Lamberti, Alfredo; Chiesura, Gabriele; Luyckx, Geert; Degrieck, Joris; Kaufmann, Markus; Vanlanduit, Steve

    2015-01-01

    The measurement of the internal deformations occurring in real-life composite components is a very challenging task, especially for those components that are rather difficult to access. Optical fiber sensors can overcome such a problem, since they can be embedded in the composite materials and serve as in situ sensors. In this article, embedded optical fiber Bragg grating (FBG) sensors are used to analyze the vibration characteristics of two real-life composite components. The first component is a carbon fiber-reinforced polymer automotive control arm; the second is a glass fiber-reinforced polymer aeronautic hinge arm. The modal parameters of both components were estimated by processing the FBG signals with two interrogation techniques: the maximum detection and fast phase correlation algorithms were employed for the demodulation of the FBG signals; the Peak-Picking and PolyMax techniques were instead used for the parameter estimation. To validate the FBG outcomes, reference measurements were performed by means of a laser Doppler vibrometer. Sensors 2015, 15 27175 The analysis of the results showed that the FBG sensing capabilities were enhanced when the recently-introduced fast phase correlation algorithm was combined with the state-of-the-art PolyMax estimator curve fitting method. In this case, the FBGs provided the most accurate results, i.e. it was possible to fully characterize the vibration behavior of both composite components. When using more traditional interrogation algorithms (maximum detection) and modal parameter estimation techniques (Peak-Picking), some of the modes were not successfully identified. PMID:26516854

  15. Dynamic Strain Measurements on Automotive and Aeronautic Composite Components by Means of Embedded Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Lamberti, Alfredo; Chiesura, Gabriele; Luyckx, Geert; Degrieck, Joris; Kaufmann, Markus; Vanlanduit, Steve

    2015-01-01

    The measurement of the internal deformations occurring in real-life composite components is a very challenging task, especially for those components that are rather difficult to access. Optical fiber sensors can overcome such a problem, since they can be embedded in the composite materials and serve as in situ sensors. In this article, embedded optical fiber Bragg grating (FBG) sensors are used to analyze the vibration characteristics of two real-life composite components. The first component is a carbon fiber-reinforced polymer automotive control arm; the second is a glass fiber-reinforced polymer aeronautic hinge arm. The modal parameters of both components were estimated by processing the FBG signals with two interrogation techniques: the maximum detection and fast phase correlation algorithms were employed for the demodulation of the FBG signals; the Peak-Picking and PolyMax techniques were instead used for the parameter estimation. To validate the FBG outcomes, reference measurements were performed by means of a laser Doppler vibrometer. Sensors 2015, 15 27175 The analysis of the results showed that the FBG sensing capabilities were enhanced when the recently-introduced fast phase correlation algorithm was combined with the state-of-the-art PolyMax estimator curve fitting method. In this case, the FBGs provided the most accurate results, i.e. it was possible to fully characterize the vibration behavior of both composite components. When using more traditional interrogation algorithms (maximum detection) and modal parameter estimation techniques (Peak-Picking), some of the modes were not successfully identified.

  16. Dynamic Strain Measurements on Automotive and Aeronautic Composite Components by Means of Embedded Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Alfredo Lamberti

    2015-10-01

    Full Text Available The measurement of the internal deformations occurring in real-life composite components is a very challenging task, especially for those components that are rather difficult to access. Optical fiber sensors can overcome such a problem, since they can be embedded in the composite materials and serve as in situ sensors. In this article, embedded optical fiber Bragg grating (FBG sensors are used to analyze the vibration characteristics of two real-life composite components. The first component is a carbon fiber-reinforced polymer automotive control arm; the second is a glass fiber-reinforced polymer aeronautic hinge arm. The modal parameters of both components were estimated by processing the FBG signals with two interrogation techniques: the maximum detection and fast phase correlation algorithms were employed for the demodulation of the FBG signals; the Peak-Picking and PolyMax techniques were instead used for the parameter estimation. To validate the FBG outcomes, reference measurements were performed by means of a laser Doppler vibrometer. Sensors 2015, 15 27175 The analysis of the results showed that the FBG sensing capabilities were enhanced when the recently-introduced fast phase correlation algorithm was combined with the state-of-the-art PolyMax estimator curve fitting method. In this case, the FBGs provided the most accurate results, i.e. it was possible to fully characterize the vibration behavior of both composite components. When using more traditional interrogation algorithms (maximum detection and modal parameter estimation techniques (Peak-Picking, some of the modes were not successfully identified.

  17. Smart pressure and temperature measurement on paper machine rolls: an embedded fiber Bragg grating sensor system enables continuous nip monitoring during paper production

    Science.gov (United States)

    Ecke, Wolfgang; Schmitt, Matthias W.; Shieh, Yang; Lindner, Eric; Zöller, Lothar

    2012-04-01

    Special fiber Bragg grating (FBG) sensor embedding and interrogation schemes have been designed to capture the momentary peak pressure forces in the nip of adjacent paper machine rolls, and the spatial distribution of these nip forces along circumference and length of the roll, for production speeds of up to 2000 m/min. Additionally, this FBG sensor system measures the temperature distribution in the roll cover. FBG sensor embedment has been investigated and optimized for the implementation of pressure force measurements in various roll cover materials. These measurements enable immediate quality control during various stages of the production process. Draw Tower Grating sensor arrays, simultaneously performing spectrometric interrogation, and autonomous power supply technologies result in an extremely robust fiberoptic sensor system operating at rotation speeds of 700 rpm, equivalent to centrifugal accelerations of 300 G.

  18. Packaging Effects on Fiber Bragg Grating Sensor Performance%光纤光珊的封装效果对其性能的影响

    Institute of Scientific and Technical Information of China (English)

    郝建忠; 高桥志郎; 蔡朝晖; 吴俊宏; 杨秀峰; 陈智浩; 吕超

    2006-01-01

    In this paper, the effects of packaging material and structure of fiber Bragg grating sensor performance are investigated. The effects of thermal expansion coefficient of different embedding materials on the temperature sensitivities of the FBG sensors are studied both theoretically and experimentally with good agreement, which provides a means for selection of FBG packaging material to achieve desiredtemperature sensitivity. We also demonstrate a 4-point bending structured FBG lateral force sensor that measures up to 242N force with well-preserved reflection spectrum, whereas for 3-point bending structure, multiple-peaks start to occur when applied force reaches 72N.

  19. Efficient iterative technique for designing bragg gratings

    DEFF Research Database (Denmark)

    Plougmann, Nikolai; Kristensen, Martin

    2004-01-01

    We present a new iterative method for designing Bragg gratings based on the Levenberg-Marquardt method of minimizing a chi-squared merit function. It is effective for designing both weak and strong gratings and is particularly well suited for unchirped gratings....

  20. Measurement of Temperature and Residual Strain during Fatigue of a CFRP Composite Using Fiber Bragg Grating Sensors

    Institute of Scientific and Technical Information of China (English)

    SHEN Xiaoyan; LIN Yuchi; WANG Wei

    2009-01-01

    Fatigue behaviour has important implications for engineering composite structures in sectors ranging from automotive to aerospace. Optical sensing technology displays excellent performance in these fields for monitoring. In this paper, temperature and residual strain during fatigue of a carbon fiber reinforced polymer(CFRP) are investigated. Four autoclaved CFRP beam specimens, with fiber Bragg grating(FBG) sensors and thermocouples embedded at selected locations, are subjected to three-point bending cyclic loading on the BOSE testing machine for fatigue testing. Thermocouples are used to measure the temperature while FBGs can sense the temperature and strain as well. Seven tests in total are conducted at different frequencies, and each test lasts for several days. From the experimental results, transient steep peaks of temperature increases (up to 2.3 ℃) are discovered at the beginning of the load. The following constant temperature increments are around 1.0 ℃, which is not relevant to frequencies from 0.1 Hz to 20 Hz and suspected due to fatigue. Residual strains of 1×10-5-2×10-5 during fatigue, fading away rapidly when unloading, are also reported. Embedded FBGs here are validated to sense temperature and strains in composite structures, which demonstrates promising potentials in structure monitoring fields. CFRP are verified to have an excellent performance during fatigue with low temperature increase and residual strain.

  1. Embedding silica and polymer fibre Bragg gratings (FBG) in plastic 3D-printed sensing patches

    DEFF Research Database (Denmark)

    Zubel, Michal G.; Sugden, Kate; Webb, David J.;

    2016-01-01

    This paper reports the first demonstration of a silica fibre Bragg grating (SOFBG) embedded in an FDM 3-D printed housing to yield a dual grating temperature-compensated strain sensor. We also report the first ever integration of polymer fibre Bragg grating (POFBG) within a 3-D printed sensing...

  2. In Search of Multi-Peaked Reflective Spectrum with Optic Fiber Bragg Grating Sensor for Dynamic Strain Measurement

    Science.gov (United States)

    Tai, Hsiang

    2006-01-01

    In a typical optic fiber Bragg grating (FBG) strain measurement, unless in an ideal static laboratory environment, the presence of vibration or often disturbance always exists, which often creates spurious multiple peaks in the reflected spectrum, resulting in a non-unique determination of strain value. In this report we attempt to investigate the origin of this phenomenon by physical arguments and simple numerical simulation. We postulate that the fiber gratings execute small amplitude transverse vibrations changing the optical path in which the reflected light traverses slightly and non-uniformly. Ultimately, this causes the multi-peak reflected spectrum.

  3. Coating process of Fiber Bragg Grating sensors for SHM applications in metallic structures

    Science.gov (United States)

    Piñeiro, E.; Grandal, T.; Asensio, A.; Rodriguez, F.

    2014-05-01

    Embedded fiber optic sensors into composites have been studied for a long time, but embedding a fiber sensor into metallic structure is beginning to study. Recently, this has raised interest due to embedded FBG in the metallic structure provide capabilities for controlling parameters of the structural health status and also information about their own process of deterioration. In this paper we study three different techniques for coating a FBG sensor: physical vapour deposition (PVD), electroless deposition and electroplating. This paper describes the experimental procedure for coating metallic fiber optic sensors and the optical characterization.

  4. Fiber Bragg grating sensors as a tool to evaluate the influence of filler on shrinkage of geopolymer matrices

    Science.gov (United States)

    Campopiano, Stefania; Iadicicco, Agostino; Messina, Francesco; Ferone, Claudio; Cioffi, Raffaele

    2015-05-01

    Geopolymer matrices represent one of the main sustainable alternatives to ordinary Portland cement (OPC) and other clinker-based blended cements. Real scale applications are limited and a relevant amount of data is still needed to assess the early age and long-term behavior of these systems. Particularly, the early-age monitoring of geopolymers represent a key parameter for mix design optimization. Most of the available methods for the measurement of temperature evolution due to polycondensation kinetics and early age deformations are related to laboratory activities. The upscaling to in situ techniques represents a crucial step toward technological assessment. To this aim, authors propose to use Fiber Bragg Gratings (FBGs) embedded in the geopolymer matrices. Starting from a case study by authors related to the design of externally bonded fiber reinforced geopolymers for strengthening of existing structures, the matrix was optimized in terms of quartz filler content. The measurements carried out by means of FBG sensors allowed to reduce filler content respect to the abovementioned work. Particularly, quartz content can be reduced by 50%. The temperature associated to polycondensation was slightly below 65°C for the three studied systems, limiting the use of designed metakaolin geopolymer to non-massive structures, since thermal cracking could occur, unless further research will be able to assess the viability of retardants. The experimental results confirm that FBG represent an accurate method for simultaneous shrinkage and temperature measurements for geopolymers and the application in real scale structures for remote sensing could help to create database on inner temperatures and early age deformations.

  5. Fiber Bragg Grating sensors for structural health monitoring of Tsing Ma bridge: background and experimental observation

    NARCIS (Netherlands)

    Chan, T.H.T.; Yu, L.; Tam, H.Y.; Ni, Y.Q.; Liu, S.Y.; Chung, W.H.; Cheng, L.K.

    2006-01-01

    The rapid expansion of the optical fiber telecommunication industry due to the explosion of the Internet has substantially driven down the cost of optical components, making fiber optic sensors more economically viable. In addition, the rapid development of fiber-optic sensors, particularly the fibe

  6. Application of the fiber Bragg grating (FBG) sensors in coal mines

    Science.gov (United States)

    Wang, Jinyu; Song, Guang-Dong; Hu, Binxin; Li, Lianqing; Liu, Tongyu

    2013-09-01

    The FBG strain sensors were applied to the Dongtan Mine to monitor the stress variation of the lined wall in the gateway retained along goaf of No. 3203 coal mining face on line. The results showed that the FBG strain sensor with high measuring range could measure the stress variation accurately during the support process of the gateway retained along goaf and could provide the basis to further optimize the support structure and to determine the support plan of the gateway retained along the goaf. The FBG micro-seismic sensors were used in Xinglong Mine to detect micro-seismic signal. The signals are well received and analyzed to determine the earthquake source and do warming. The FBG sensors and detecting system show great prospect in micro-seismic detection, and geological disasters detecting.

  7. Advanced Interrogation of Fiber-Optic Bragg Grating and Fabry-Perot Sensors with KLT Analysis

    OpenAIRE

    Daniele Tosi

    2015-01-01

    The Karhunen-Loeve Transform (KLT) is applied to accurate detection of optical fiber sensors in the spectral domain. By processing an optical spectrum, although coarsely sampled, through the KLT, and subsequently processing the obtained eigenvalues, it is possible to decode a plurality of optical sensor results. The KLT returns higher accuracy than other demodulation techniques, despite coarse sampling, and exhibits higher resilience to noise. Three case studies of KLT-based processing are pr...

  8. Dynamic fiber Bragg grating sensing method

    Science.gov (United States)

    Ho, Siu Chun Michael; Ren, Liang; Li, Hongnan; Song, Gangbing

    2016-02-01

    The measurement of high frequency vibrations is important in many scientific and engineering problems. This paper presents a novel, cost effective method using fiber optic fiber Bragg gratings (FBGs) for the measurement of high frequency vibrations. The method uses wavelength matched FBG sensors, with the first sensor acting as a transmission filter and the second sensor acting as the sensing portion. Energy fluctuations in the reflection spectrum of the second FBG due to wavelength mismatch between the sensors are captured by a photodiode. An in-depth analysis of the optical circuit is provided to predict the behavior of the method as well as identify ways to optimize the method. Simple demonstrations of the method were performed with the FBG sensing system installed on a piezoelectric transducer and on a wind turbine blade. Vibrations were measured with sampling frequencies up to 1 MHz for demonstrative purposes. The sensing method can be multiplexed for use with multiple sensors, and with care, can be retrofitted to work with FBG sensors already installed on a structure.

  9. Design and modeling of an all-optical frequency modulated MEMS strain sensor using nanoscale Bragg gratings

    DEFF Research Database (Denmark)

    Reck, Kasper; Almind, Ninia Sejersen; Mar, Mikkel Dysseholm;

    2009-01-01

    comparable designs, e.g. Fabry-Perot and Mach-Zender. Also, multiplexing of several sensors with different period gratings, allow sensors to be connected to a single fiber, thereby minimizing cabling and simplifying readout. We show through analytical analysis and finite element modeling (FEM) that large...

  10. Field monitoring of static, dynamic, and statnamic pile loading tests using fibre Bragg grating strain sensors

    Science.gov (United States)

    Li, Jin; Correia, Ricardo P.; Chehura, Edmon; Staines, Stephen; James, Stephen W.; Tatam, Ralph; Butcher, Antony P.; Fuentes, Raul

    2009-10-01

    Pile loading test plays an important role in the field of piling engineering. In order to gain further insight into the load transfer mechanism, strain gauges are often used to measure local strains along the piles. This paper reports a case whereby FBG strain sensors was employed in a field trial conducted on three different types of pile loading tests in a glacial till. The instrumentation systems were configured to suit the specific characteristic of each type of test. Typical test results are presented. The great potential of using FBG sensors for pile testing is shown.

  11. A plating method for metal coating of fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    Yulong Li; Hua Zhang; Yan Feng; Gang Peng

    2009-01-01

    We present a method for metal coating optical fiber and in-fiber Bragg grating. The technology process which is based on electroless plating and electroplating method is described in detail. The fiber is firstly coated with a thin copper or nickel plate with electroless plating method. Then, a thicker nickel plate is coated on the surface of the conductive layer. Under the optimum conditions, the surfaces of chemical plating and electroplating coatings are all smooth and compact. There is no visible defect found in the cross-section. Using this two-step metallization method, the in-fiber Bragg grating can be well protected and its thermal sensitivity can be enhanced. After the metallization process, the fiber sensor is successfully embedded in the 42CrMo steel by brazing method. Thus a smart metal structure is achieved. The embedding results show that the plating method for metallization protection of in-fiber Bragg grating is effective.

  12. Single mode step-index polymer optical fiber for humidity insensitive high temperature fiber Bragg grating sensors

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Fasano, Andrea; Stefani, Alessio;

    2016-01-01

    preform. The fabricated single-mode step-index (SI) polymer optical fiber (POF) has a 4.8µm core made from TOPAS grade 5013S-04 with a glass transition temperature of 134°C and a 150 µm cladding made from ZEONEX grade 480R with a glass transition temperature of 138°C. The key advantages of the proposed...... SIPOF are low water absorption, high operating temperature and chemical inertness to acids and bases and many polar solvents as compared to the conventional poly-methyl-methacrylate (PMMA) and polystyrene based POFs. In addition, the fiber Bragg grating writing time is short compared to microstructured...

  13. Planar Bragg Grating Sensors—Fabrication and Applications: A Review

    Directory of Open Access Journals (Sweden)

    I. J. G. Sparrow

    2009-01-01

    Full Text Available We discuss the background and technology of planar Bragg grating sensors, reviewing their development and describing the latest developments. The physical operating principles are discussed, relating device operation to user requirements. Recent performance of such devices includes a planar Bragg grating sensor design which allows refractive index resolution of 1.9×10−6 RIU and temperature resolution of 0.03∘C. This sensor design is incorporated into industrialised applications allowing the sensor to be used for real time sensing in intrinsically safe, high-pressure pipelines, or for insertion probe applications such as fermentation. Initial data demonstrating the ability to identify solvents and monitor long term industrial processes is presented. A brief review of the technology used to fabricate the sensors is given along with examples of the flexibility afforded by the technique.

  14. A wide dynamics and fast scan interrogating method for a fiber Bragg grating sensor network implemented using code division multiple access.

    Science.gov (United States)

    Kim, Youngbok; Jeon, Sie-Wook; Kwon, Won-Bae; Park, Chang-Soo

    2012-01-01

    We propose and demonstrate a fiber Bragg grating (FBG) sensor network employing the code division multiple access (CDMA) technique to identify information from individual sensors. To detect information without considering time delays between sensors, a sliding correlation method is applied, in which two different signals with the same pseudo-random binary sequence (PRBS) pattern, but slightly different frequencies, are applied to the source and detector sides. Moreover, for time domain detection, a wavelength-to-time conversion technique using a wavelength dispersive medium is introduced. The experimental results show that the proposed sensor network has a wide strain dynamic range of 2,400 με and a low crosstalk of 950:1. PMID:22778619

  15. A Wide Dynamics and Fast Scan Interrogating Method for a Fiber Bragg Grating Sensor Network Implemented Using Code Division Multiple Access

    Directory of Open Access Journals (Sweden)

    Chang-Soo Park

    2012-05-01

    Full Text Available We propose and demonstrate a fiber Bragg grating (FBG sensor network employing the code division multiple access (CDMA technique to identify information from individual sensors. To detect information without considering time delays between sensors, a sliding correlation method is applied, in which two different signals with the same pseudo-random binary sequence (PRBS pattern, but slightly different frequencies, are applied to the source and detector sides. Moreover, for time domain detection, a wavelength-to-time conversion technique using a wavelength dispersive medium is introduced. The experimental results show that the proposed sensor network has a wide strain dynamic range of 2,400 μe and a low crosstalk of 950:1.

  16. Estimation of Curvature Changes for Steel-Concrete Composite Bridge Using Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Donghoon Kang

    2013-01-01

    Full Text Available This study is focused on the verification of the key idea of a newly developed steel-concrete composite bridge. The key idea of the proposed bridge is to reduce the design moment by applying vertical prestressing force to steel girders, so that a moment distribution of a continuous span bridge is formed in a simple span bridge. For the verification of the key technology, curvature changes of the bridge should be monitored sequentially at every construction stage. A pair of multiplexed FBG sensor arrays is proposed in order to measure curvature changes in this study. They are embedded in a full-scale test bridge and measured local strains, which are finally converted to curvatures. From the result of curvature changes, it is successfully ensured that the key idea of the proposed bridge, expected theoretically, is viable.

  17. A no adhesive and temperature-insensitive package design of fiber Bragg grating pressure sensor

    Science.gov (United States)

    Wang, Hui; Zhu, Jun; Yin, Hao; Zhang, Zhao; Tang, Haiyu; Yu, Benli

    2012-11-01

    In this study, an innovative temperature-insensitive and no adhesive package for FBG pressure sensor was designed. We presents an package construction to compensate for temperature deviation of a FBG by mechanical properties of different metal materials; the package realize no adhesive utilizing combined technique of electroless plating NI-P and electroplating NI and laser spot welding technology. On the basis of the study on the Material structural properties and the compensation principles analysis of the FBG, the finite element method is used to analysis of the feasibility of the construction and optimize the construction parameters. The results show that this compensation construction can effectively reduce the temperature sensitivity of the FBG.

  18. Spot event detection along a large-scale sensor based on ultra-weak fiber Bragg gratings using time-frequency analysis.

    Science.gov (United States)

    Ricchiuti, Amelia Lavinia; Sales, Salvador

    2016-02-10

    A simple scheme for interrogating a 5 m long photonics device and its potential applications to quasi-distributed fiber sensing is proposed. The sensor consists of an array of 500 identical, very weak fiber Bragg gratings (FBGs). The gratings are 9 mm long and have been serially written in cascade along a single optical fiber. The measurement system is based on a combination of optical time domain reflectometry and frequency scanning of the interrogating pulse. The time-frequency analysis is performed by launching an optical pulse into the sensor and retrieving and analyzing the back-reflected signal. The measurement of the temperature, length, and position of spot events along the sensors is demonstrated with good accuracy. As both spatial and temperature resolution of the method depend on the input pulse duration, the system performance can be controlled and optimized by properly choosing the temporal duration of the interrogating pulse. A spatial resolution of 9 mm (ultimately dictated by one grating length) has been obtained with an 80 ps optical pulse, while a temperature resolution of less than 0.42 K has been demonstrated using a 500 ps incident pulse. The sensor proposed proves to be simple, robust, and polarization insensitive and alleviates the instrumentation complexity for distributed sensing applications. PMID:26906375

  19. Spot event detection along a large-scale sensor based on ultra-weak fiber Bragg gratings using time-frequency analysis.

    Science.gov (United States)

    Ricchiuti, Amelia Lavinia; Sales, Salvador

    2016-02-10

    A simple scheme for interrogating a 5 m long photonics device and its potential applications to quasi-distributed fiber sensing is proposed. The sensor consists of an array of 500 identical, very weak fiber Bragg gratings (FBGs). The gratings are 9 mm long and have been serially written in cascade along a single optical fiber. The measurement system is based on a combination of optical time domain reflectometry and frequency scanning of the interrogating pulse. The time-frequency analysis is performed by launching an optical pulse into the sensor and retrieving and analyzing the back-reflected signal. The measurement of the temperature, length, and position of spot events along the sensors is demonstrated with good accuracy. As both spatial and temperature resolution of the method depend on the input pulse duration, the system performance can be controlled and optimized by properly choosing the temporal duration of the interrogating pulse. A spatial resolution of 9 mm (ultimately dictated by one grating length) has been obtained with an 80 ps optical pulse, while a temperature resolution of less than 0.42 K has been demonstrated using a 500 ps incident pulse. The sensor proposed proves to be simple, robust, and polarization insensitive and alleviates the instrumentation complexity for distributed sensing applications.

  20. Performance of low-cost few-mode fiber Bragg grating sensor systems: polarization sensitivity and linearity of temperature and strain response

    DEFF Research Database (Denmark)

    Ganziy, Denis; Rose, Bjarke; Bang, Ole

    2016-01-01

    We evaluate whether 850 nm fiber Bragg grating (FBG) sensor systems can use low-cost 1550 nm telecom fibers; in other words, how detrimental the influence of higher-order modes is to the polarization stability and linearity of the strain and temperature response. We do this by comparing...... polarization sensitivity of a few-mode 850 nm FBG sensor to a strictly single-mode 850 nm FBG sensor system using 850 nm single-mode fibers. We also compare the performance of the FBGs in strain and temperature tests. Our results show that the polarization stability and the linearity of the response degrade...... due to the presence of the higher-order modes. We demonstrate that, by using simple coiling of the 1550 nm fiber, one can regain the performance of the few-mode system and make it usable for high precision measurements....

  1. Ultrafast laser inscribed fiber Bragg gratings for sensing applications

    Science.gov (United States)

    Mihailov, Stephen J.

    2016-05-01

    Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on femtosecond infrared laser-material processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This tutorial paper will present a review of some of the more recent developments.

  2. Investigation of thermal cycling response and stability of polymer coated Fiber Bragg Grating sensors at cryogenic temperatures

    International Nuclear Information System (INIS)

    The purpose of this paper is to study the polymer coated FBG sensor characteristics. For this study, FBG sensors coated with Acrylate, sensor coated with Ormocer (polymer) and uncoated FBG sensors were arranged in single fiber using wavelength division multiplexing (WDM) scheme. The sensitivity of the gratings coated with Ormocer and acrylate was found to be about 2.7 and 2.3 times greater than that of the bare FBG at low temperature. Also, the sensor array was found to be highly stable and shows good repeatability and reproducibility after 200 thermal cycling. The time response of the Ormocer coated sensor which was protected by a 1.6mm diameter stainless steel capillary tube was found to be nearly 12 sec. Expanded uncertainty of Ormocer coated sensor has been estimated to be 0.13 K at 77 K. (author)

  3. Sampled phase-shift fiber Bragg gratings

    Institute of Scientific and Technical Information of China (English)

    Xu Wang(王旭); Chongxiu Yu(余重秀); Zhihui Yu(于志辉); Qiang Wu(吴强)

    2004-01-01

    A phase-shift fiber Bragg grating (FBG) with sampling is proposed to generate a multi-channel bandpass filter in the background of multi-channel stopbands. The sampled noire fiber gratings are analyzed by Fourier transform theory first, and then simulation and experiment are performed, the results show that transmission peaks are opened in every reflective channel, the spectrum shape of every channel is identical.It can be used to fabricate multi-wavelength distributed feedback (DFB) fiber laser.

  4. Fabrication and characterization of polycarbonate microstructured polymer optical fibers for high-temperature-resistant fiber Bragg grating strain sensors

    DEFF Research Database (Denmark)

    Fasano, Andrea; Woyessa, Getinet; Stajanca, Pavol;

    2016-01-01

    Here we present the fabrication of a solid-core microstructured polymer optical fiber (mPOF) made of polycarbonate (PC), and report the first experimental demonstration of a fiber Bragg grating (FBG) written in a PC optical fiber. The PC used in this work has a glass transition temperature of 145°C....... We also characterize the mPOF optically and mechanically, and further test the sensitivity of the PC FBG to strain and temperature. We demonstrate that the PC FBG can bear temperatures as high as 125°C without malfunctioning. In contrast, polymethyl methacrylate-based FBG technology is generally...

  5. Single mode step-index polymer optical fiber for humidity insensitive high temperature fiber Bragg grating sensors.

    Science.gov (United States)

    Woyessa, Getinet; Fasano, Andrea; Stefani, Alessio; Markos, Christos; Nielsen, Kristian; Rasmussen, Henrik K; Bang, Ole

    2016-01-25

    We have fabricated the first single-mode step-index and humidity insensitive polymer optical fiber operating in the 850 nm wavelength ranges. The step-index preform is fabricated using injection molding, which is an efficient method for cost effective, flexible and fast preparation of the fiber preform. The fabricated single-mode step-index (SI) polymer optical fiber (POF) has a 4.8µm core made from TOPAS grade 5013S-04 with a glass transition temperature of 134°C and a 150 µm cladding made from ZEONEX grade 480R with a glass transition temperature of 138°C. The key advantages of the proposed SIPOF are low water absorption, high operating temperature and chemical inertness to acids and bases and many polar solvents as compared to the conventional poly-methyl-methacrylate (PMMA) and polystyrene based POFs. In addition, the fiber Bragg grating writing time is short compared to microstructured POFs. PMID:26832507

  6. Uniform spacing interrogation of a Fourier domain mode-locked fiber Bragg grating sensor system using a polarization-maintaining fiber Sagnac interferometer

    International Nuclear Information System (INIS)

    A novel linearized interrogation method is presented for a Fourier domain mode-locked (FDML) fiber Bragg grating (FBG) sensor system. In a high speed regime over several tens of kHz modulations, a sinusoidal wave is available to scan the center wavelength of an FDML wavelength-swept laser, instead of a conventional triangular wave. However, sinusoidal wave modulation suffers from an exaggerated non-uniform wavelength-spacing response in demodulating the time-encoded parameter to the absolute wavelength. In this work, the calibration signal from a polarization-maintaining fiber Sagnac interferometer shares the FDML wavelength-swept laser for FBG sensors to convert the time-encoded FBG signal to the wavelength-encoded uniform-spacing signal. (paper)

  7. Temperature-Strain Discrimination Sensor Using a WDM Chirped in-Fibre Bragg Grating and an Extrinsic Fabry-Pérot

    Institute of Scientific and Technical Information of China (English)

    RAO Yun-Jiang; ZENG Xiang-Kai; ZHU Yong; WANG Yi-Ping; ZHU Tao; RAN Zeng-Ling; ZHANG Lin; IAN Bennion

    2001-01-01

    A novel fibre-optic sensing system used for temperature-strain discrimination is presented. This system consists of an extrinsic Fabry-Pérot interferometric sensor (EFPI) and a chirped in-fibre Bragg grating (CFBG) in series.The EFPI and the CFBG are wavelength-division-multiplexed (WDM) to provide strain and temperature infor mation, respectively. The wavelength-shift of the CFBG induced by temperature change in the 1.55 μm region is interrogated with an intensity-based scheme, allowing fast measurement of temperature. The cavity length change of the EFPI is measured in the 1.3μm region, allowing strain to be measured without cross-talk from the temperature sensor, i.e. the CFBG. Experimental results show that the achieved accuracies for strain and temperature measurement are ±20 × 10-6 and ±2°C, respectively.

  8. Novel RF Interrogation of a Fiber Bragg Grating Sensor Using Bidirectional Modulation of a Mach-Zehnder Electro-Optical Modulator

    Directory of Open Access Journals (Sweden)

    Jae-Kyung Pan

    2013-07-01

    Full Text Available We propose and experimentally demonstrate the novel radio-frequency (RF interrogation of a fiber Bragg grating (FBG sensor using bidirectional modulation of a Mach-Zehnder electro-optical modulator (MZ-EOM. Based on the microwave photonic technique and active detection, the transfer function of the proposed system was obtained, and the time delay was calculated from the change in the free spectral range (FSR at different wavelengths over the optimal measuring range. The results show that the time delay and the wavelength variation have a good linear relationship, with a gradient of 9.31 ps/nm. An actual measurement taken with a sensing FBG for temperature variation shows the relationship with a gradient of 0.93 ps/10 °C. The developed system could be used for FBG temperature or strain sensing and other multiplexed sensor applications.

  9. Development of thin-slice fiber Bragg grating-giant magnetostrictive material sensors used for measuring magnetic field of magnetic bearings

    Science.gov (United States)

    Ding, Guoping; Wang, Huaqiang; Liu, Jiayi; Gao, Bin; Zhang, Biyun

    2015-10-01

    The magnetic field is a physical medium used to realize the levitation and motion control of magnetic bearings. It is necessary to conduct the air-gap flux density measurement so as to validate theoretical analyses and provide instructions for practical design. A thin-slice fiber Bragg grating-giant magnetostrictive material (FBG-GMM) sensor, in which the FBG was stuck perpendicular to the principal magnetostriction orientation of a thin GMM slice, was proposed to measure magnetic-flux density in the small air gap. The configuration of FBG-GMM sensor was the same with that of a sensor of 1.5 mm×14 mm×7 mm TbDyFe slice stuck with a 1300 nm-wavelength FBG on the side of the slice. The FBG-GMM magnetic field sensor was tested on an U-shape electromagnet test setup under static conditions. The sensor had a linear region of 0.121 to 0.261 T with the sensitivity of 1089.056 pm/T. The FBG-GMM magnetic field sensor was introduced to measure the air-gap flux density of radial magnetic bearings. Measurement of static flux density was conducted with 2 FBG-GMM sensors compensated with a temperature FBG; and the measured data showed that the FBG-GMM sensor had feasible linear region and sensitivity to measure the air-gap flux density of magnetic bearings.

  10. Thermal annealing of tilted fiber Bragg gratings

    Science.gov (United States)

    González-Vila, Á.; Rodríguez-Cobo, L.; Mégret, P.; Caucheteur, C.; López-Higuera, J. M.

    2016-05-01

    We report a practical study of the thermal decay of cladding mode resonances in tilted fiber Bragg gratings, establishing an analogy with the "power law" evolution previously observed on uniform gratings. We examine how this process contributes to a great thermal stability, even improving it by means of a second cycle slightly increasing the annealing temperature. In addition, we show an improvement of the grating spectrum after annealing, with respect to the one just after inscription, which suggests the application of this method to be employed to improve saturation issues during the photo-inscription process.

  11. Compressive and tensile strain sensing using a polymer planar Bragg grating.

    Science.gov (United States)

    Rosenberger, M; Hessler, S; Belle, S; Schmauss, B; Hellmann, R

    2014-03-10

    A polymer planar Bragg grating sensor is used for measuring both mechanical compressive and tensile strain. The planar waveguide with integrated Bragg grating is fabricated in bulk Polymethylmethacrylate in a single writing step using combined amplitude and phase mask technique. After butt coupling of a single-mode optical fiber the planar structure can be applied for measuring both mechanical tensile and compressive strain alongside the integrated waveguide without the need of further modifications. In this respect, we particularly report for the first time compressive strain measurements using a polymer Bragg grating. Furthermore, the sensitivity of the sensor against tensile and compressive strain, its reproducibility and hysteresis are investigated and discussed.

  12. Magneto-Optic Field Coupling in Optical Fiber Bragg Gratings

    Science.gov (United States)

    Carman, Gregory P. (Inventor); Mohanchandra, Panduranga K. (Inventor); Emmons, Michael C. (Inventor); Richards, William Lance (Inventor)

    2016-01-01

    The invention is a magneto-optic coupled magnetic sensor that comprises a standard optical fiber Bragg grating system. The system includes an optical fiber with at least one Bragg grating therein. The optical fiber has at least an inner core and a cladding that surrounds the inner core. The optical fiber is part of an optical system that includes an interrogation device that provides a light wave through the optical fiber and a system to determine the change in the index of refraction of the optical fiber. The cladding of the optical fiber comprises at least a portion of which is made up of ferromagnetic particles so that the ferromagnetic particles are subject to the light wave provided by the interrogation system. When a magnetic field is present, the ferromagnetic particles change the optical properties of the sensor directly.

  13. Fiber sensing system based on a bragg grating and optical time domain reflectometry

    OpenAIRE

    Chin, Sanghoon; Thévenaz, Luc

    2013-01-01

    Optic fiber sensor characterized in that the sensing fiber is provided with a continuous Bragg grating covering the entire fiber length which is dedicated to sensing and along which spatially resolved measurements are performed.

  14. Highly reproducible Bragg grating acousto-ultrasonic contact transducers

    Science.gov (United States)

    Saxena, Indu Fiesler; Guzman, Narciso; Lieberman, Robert A.

    2014-09-01

    Fiber optic acousto-ultrasonic transducers offer numerous applications as embedded sensors for impact and damage detection in industrial and aerospace applications as well as non-destructive evaluation. Superficial contact transducers with a sheet of fiber optic Bragg gratings has been demonstrated for guided wave ultrasound based measurements. It is reported here that this method of measurement provides highly reproducible guided ultrasound data of the test composite component, despite the optical fiber transducers not being permanently embedded in it.

  15. Fiber Bragg Gratings Embedded in 3D-Printed Scaffolds

    CERN Document Server

    Liacouras, Peter; Choudhry, Khazar; Strouse, G F; Ahmed, Zeeshan

    2015-01-01

    In recent years there has been considerable interest in utilizing embedded fiber optic based sensors for fabricating smart materials. One of the primary motivations is to provide real-time information on the structural integrity of the material so as to enable proactive actions that prevent catastrophic failure. In this preliminary study we have examined the impact of embedding on the temperature-dependent response of fiber Bragg gratings.

  16. Structure Optimization of Fiber Bragg Grating Strain Sensors%光纤布喇格光栅应变传感器结构优化研究

    Institute of Scientific and Technical Information of China (English)

    袁子琳; 龚元; 马耀远; 杜磊; 吴宇; 饶云江; 吴慧娟; 王浚璞; 万夫

    2012-01-01

    提出了一种改进的光纤光栅应变传感器结构,用有限元分析软件对其进行建模和静力仿真,得到其应力分布和光栅区域的应变情况.在整体宽度与厚度相等的情况下,此结构的灵敏度约为传统“工”字型结构的600倍.进一步分析了其关键区域的6个结构参量对应变灵敏度及量程的影响.筛选、设计并加工出不同尺寸的两种应变片,分别用UV胶与玻璃焊料对光栅进行封装,得到灵敏度分别为:249 pm/N、330 pm/N和1.1 pm/N.比较分析表明,本文提供的分析方法与数据,可为不同工程应用场合的最优结构设计提供依据.%The dependence of a fiber Bragg grating strain sensor on the improved structure parameters was investigated both numerically and experimentally. The stress distribution and the strain of the grating region was obtained. In the case of the overall width and thickness are equal, the sensitivity of this structure is about 600 times higher than the traditional I-shaped structure. The influence of the 6 key structure parameters on the strain sensitivity and the measurement range was analyzed in detail. Experimental results were also given compared with the numerical simulated results. The gratings were packaged respectively with UV glue and glass solder to get the sensitivities were: 249 pm/N, 330 pm/N and 1. 1 pm/N. The analysis method and data provided a basis for structural optimum design of fiber Bragg grating strain sensors in different applications.

  17. Stationary Light Pulses without Bragg Gratings

    CERN Document Server

    Lin, Yen-Wei; Peters, Thorsten; Liao, Wen-Te; Cho, Hung-Wen; Guan, Pei-Chen; Yu, Ite A

    2008-01-01

    The underlying mechanism of the stationary light pulse (SLP) was identified as a band gap being created by a Bragg grating formed by two counter-propagating coupling fields of similar wavelength. Here we present a more general view of the formation of SLPs, namely several balanced four-wave mixing processes sharing the same ground-state coherence. Utilizing this new concept we report the first experimental observation of a bichromatic SLP at wavelengths for which no Bragg grating can be established. We also demonstrate the production of a SLP directly from a propagating light pulse without prior storage. Being easily controlled externally makes SLPs a very versatile tool for low-light-level nonlinear optics and quantum information manipulation.

  18. Pure Bending Characteristic of Tilted Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    Bo Liu; Yin-Ping Miao; Hai-Bin Zhou; Qi-Da Zhao

    2008-01-01

    a novel structure of the pure macro-bending sensor based on the tilted fiber Bragg grating (TFBG) is proposed. The TFBG located in the half circle with the different diameters is bent at a constant angle with respect to the tilted grating planes. With the variations of the curvature, the core-mode resonance is unchanged and the transmission power of cladding modes detected by the photodiodes varies linearly with curvature, while the ghost mode changes by the form of two-order polynomial. So we can use the transmission power of ghost mode or other cladding modes to detect bending curvature as shape sensor. From a practical point of view, the sensor proposed here is simple, low cost and easy to implement. Moreover, it is possible to make a temperature-insensitive shape sensor due to the same temperature characteristic between the core mode and the cladding modes.

  19. Temperature effects in concrete structures measured with fibre Bragg grating

    Science.gov (United States)

    Silva, Jean C.; Martelli, Cicero; Penner, Elisabeth; Kalinowski, Hypolito J.

    2004-06-01

    We analyze the action of fire, causing degradation in a concrete cantilever beam using dynamic testing. The structure is instrumented with two fiber Bragg gratings (FBG) sensors. One of them is used to measure vibration and another one is used to measure temperature inside of the cantilever beam, while the beam is exposed to fire. The temperature in the cantilever beam increased until 150°C and a reduction in the strength of concrete can be observed through the modal analysis. A fiber Bragg grating interrogation system, based on tunable filter method, is used for the static and dynamic measurements during the experiments. That system has low cost and it is easy to assemble and maintain when compared to other available instruments.

  20. Processing of Signals from Fiber Bragg Gratings Using Unbalanced Interferometers

    Science.gov (United States)

    Adamovsky, Grigory; Juergens, Jeff; Floyd, Bertram

    2005-01-01

    Fiber Bragg gratings (FBG) have become preferred sensory structures in fiber optic sensing system. High sensitivity, embedability, and multiplexing capabilities make FBGs superior to other sensor configurations. The main feature of FBGs is that they respond in the wavelength domain with the wavelength of the returned signal as the indicator of the measured parameter. The wavelength is then converted to optical intensity by a photodetector to detect corresponding changes in intensity. This wavelength-to-intensity conversion is a crucial part in any FBG-based sensing system. Among the various types of wavelength-to-intensity converters, unbalanced interferometers are especially attractive because of their small weight and volume, lack of moving parts, easy integration, and good stability. In this paper we investigate the applicability of unbalanced interferometers to analyze signals reflected from Bragg gratings. Analytical and experimental data are presented.

  1. Model Study of the Influence of Ambient Temperature and Installation Types on Surface Temperature Measurement by Using a Fiber Bragg Grating Sensor

    Directory of Open Access Journals (Sweden)

    Yi Liu

    2016-07-01

    Full Text Available Surface temperature is an important parameter in clinical diagnosis, equipment state control, and environmental monitoring fields. The Fiber Bragg Grating (FBG temperature sensor possesses numerous significant advantages over conventional electrical sensors, thus it is an ideal choice to achieve high-accuracy surface temperature measurements. However, the effects of the ambient temperature and installation types on the measurement of surface temperature are often overlooked. A theoretical analysis is implemented and a thermal transfer model of a surface FBG sensor is established. The theoretical and simulated analysis shows that both substrate strain and the temperature difference between the fiber core and hot surface are the most important factors which affect measurement accuracy. A surface-type temperature standard setup is proposed to study the measurement error of the FBG temperature sensor. Experimental results show that there are two effects influencing measurement results. One is the “gradient effect”. This results in a positive linear error with increasing surface temperature. Another is the “substrate effect”. This results in a negative non-linear error with increasing surface temperature. The measurement error of the FBG sensor with single-ended fixation are determined by the gradient effect and is a linear error. It is not influenced by substrate expansion. Thus, it can be compensated easily. The measurement errors of the FBG sensor with double-ended fixation are determined by the two effects and the substrate effect is dominant. The measurement error change trend of the FBG sensor with fully-adhered fixation is similar to that with double-ended fixation. The adhesive layer can reduce the two effects and measurement error. The fully-adhered fixation has lower error, however, it is easily affected by substrate strain. Due to its linear error and strain-resistant characteristics, the single-ended fixation will play an

  2. Model Study of the Influence of Ambient Temperature and Installation Types on Surface Temperature Measurement by Using a Fiber Bragg Grating Sensor.

    Science.gov (United States)

    Liu, Yi; Zhang, Jun

    2016-07-01

    Surface temperature is an important parameter in clinical diagnosis, equipment state control, and environmental monitoring fields. The Fiber Bragg Grating (FBG) temperature sensor possesses numerous significant advantages over conventional electrical sensors, thus it is an ideal choice to achieve high-accuracy surface temperature measurements. However, the effects of the ambient temperature and installation types on the measurement of surface temperature are often overlooked. A theoretical analysis is implemented and a thermal transfer model of a surface FBG sensor is established. The theoretical and simulated analysis shows that both substrate strain and the temperature difference between the fiber core and hot surface are the most important factors which affect measurement accuracy. A surface-type temperature standard setup is proposed to study the measurement error of the FBG temperature sensor. Experimental results show that there are two effects influencing measurement results. One is the "gradient effect". This results in a positive linear error with increasing surface temperature. Another is the "substrate effect". This results in a negative non-linear error with increasing surface temperature. The measurement error of the FBG sensor with single-ended fixation are determined by the gradient effect and is a linear error. It is not influenced by substrate expansion. Thus, it can be compensated easily. The measurement errors of the FBG sensor with double-ended fixation are determined by the two effects and the substrate effect is dominant. The measurement error change trend of the FBG sensor with fully-adhered fixation is similar to that with double-ended fixation. The adhesive layer can reduce the two effects and measurement error. The fully-adhered fixation has lower error, however, it is easily affected by substrate strain. Due to its linear error and strain-resistant characteristics, the single-ended fixation will play an important role in the FBG sensor

  3. Model Study of the Influence of Ambient Temperature and Installation Types on Surface Temperature Measurement by Using a Fiber Bragg Grating Sensor.

    Science.gov (United States)

    Liu, Yi; Zhang, Jun

    2016-01-01

    Surface temperature is an important parameter in clinical diagnosis, equipment state control, and environmental monitoring fields. The Fiber Bragg Grating (FBG) temperature sensor possesses numerous significant advantages over conventional electrical sensors, thus it is an ideal choice to achieve high-accuracy surface temperature measurements. However, the effects of the ambient temperature and installation types on the measurement of surface temperature are often overlooked. A theoretical analysis is implemented and a thermal transfer model of a surface FBG sensor is established. The theoretical and simulated analysis shows that both substrate strain and the temperature difference between the fiber core and hot surface are the most important factors which affect measurement accuracy. A surface-type temperature standard setup is proposed to study the measurement error of the FBG temperature sensor. Experimental results show that there are two effects influencing measurement results. One is the "gradient effect". This results in a positive linear error with increasing surface temperature. Another is the "substrate effect". This results in a negative non-linear error with increasing surface temperature. The measurement error of the FBG sensor with single-ended fixation are determined by the gradient effect and is a linear error. It is not influenced by substrate expansion. Thus, it can be compensated easily. The measurement errors of the FBG sensor with double-ended fixation are determined by the two effects and the substrate effect is dominant. The measurement error change trend of the FBG sensor with fully-adhered fixation is similar to that with double-ended fixation. The adhesive layer can reduce the two effects and measurement error. The fully-adhered fixation has lower error, however, it is easily affected by substrate strain. Due to its linear error and strain-resistant characteristics, the single-ended fixation will play an important role in the FBG sensor

  4. Model Study of the Influence of Ambient Temperature and Installation Types on Surface Temperature Measurement by Using a Fiber Bragg Grating Sensor

    Science.gov (United States)

    Liu, Yi; Zhang, Jun

    2016-01-01

    Surface temperature is an important parameter in clinical diagnosis, equipment state control, and environmental monitoring fields. The Fiber Bragg Grating (FBG) temperature sensor possesses numerous significant advantages over conventional electrical sensors, thus it is an ideal choice to achieve high-accuracy surface temperature measurements. However, the effects of the ambient temperature and installation types on the measurement of surface temperature are often overlooked. A theoretical analysis is implemented and a thermal transfer model of a surface FBG sensor is established. The theoretical and simulated analysis shows that both substrate strain and the temperature difference between the fiber core and hot surface are the most important factors which affect measurement accuracy. A surface-type temperature standard setup is proposed to study the measurement error of the FBG temperature sensor. Experimental results show that there are two effects influencing measurement results. One is the “gradient effect”. This results in a positive linear error with increasing surface temperature. Another is the “substrate effect”. This results in a negative non-linear error with increasing surface temperature. The measurement error of the FBG sensor with single-ended fixation are determined by the gradient effect and is a linear error. It is not influenced by substrate expansion. Thus, it can be compensated easily. The measurement errors of the FBG sensor with double-ended fixation are determined by the two effects and the substrate effect is dominant. The measurement error change trend of the FBG sensor with fully-adhered fixation is similar to that with double-ended fixation. The adhesive layer can reduce the two effects and measurement error. The fully-adhered fixation has lower error, however, it is easily affected by substrate strain. Due to its linear error and strain-resistant characteristics, the single-ended fixation will play an important role in the FBG

  5. Thermal Expansion Measurements in Fresh and Saline Ice Using Fiber Optic Strain Gauges and Multipoint Temperature Sensors Based on Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Aleksey Marchenko

    2016-01-01

    Full Text Available This paper describes the use of Fiber Bragg Grating (FBG sensors to investigate the thermomechanical properties of saline ice. FBG sensors allowed laboratory measurements of thermal expansion of ice samples with a range of different sizes and geometries. The high sampling frequency, accuracy, and resolution of the FBG sensors provide good quality data across a temperature range from 0°C to −20°C. Negative values of the effective coefficient of thermal expansion were observed in ice samples with salinities 6 ppt, 8 ppt, and 9.4 ppt. A model is formulated under which structural transformations in the ice, caused by temperature changes, can lead to brine transfer from closed pockets to permeable channels, and vice versa. This model is compared to experimental data. Further, in experiments with confined floating ice, heating as well as thermal expansion due to vertical migration of liquid brine, caused by under-ice water pressure, was observed.

  6. Detection of premature browning in ground beef with an integrated optical-fibre based sensor using reflection spectroscopy and fibre Bragg grating technology

    International Nuclear Information System (INIS)

    This paper reports on an optical fibre based sensor system to detect the occurrence of premature browning in ground beef. Premature browning (PMB) occurs when, at a temperature below the pasteurisation temperature of 71 deg. C, there are no traces of pink meat left in the patty. PMB is more frequent if poorer quality beef or beef that has been stored under imperfect conditions. The experimental work pertaining to this paper involved cooking fresh meat and meat that has been stored in a freezer for, 1 week, 1 month and 3 months and recording the reflected spectra and temperature at the core of the product, during the cooking process, in order to develop a classifier based on the spectral response and using a Self-Organising Map (SOM) to classify the patties into one of four categories, based on their colour. Further tests were also carried out on developing an all-optical fibre sensor for measuring both the temperature and colour in a single integrated probe. The integrated probe contains two different sensor concepts, one to monitor temperature, based on Fibre Bragg Grating (FBG) technology and a second for meat quality, based on reflection spectroscopy in the visible wavelength range

  7. Fiber Bragg Grating Temperature Sensors in a 6.5-MW Generator Exciter Bridge and the Development and Simulation of Its Thermal Model

    Science.gov (United States)

    de Morais Sousa, Kleiton; Probst, Werner; Bortolotti, Fernando; Martelli, Cicero; da Silva, Jean Carlos Cardozo

    2014-01-01

    This work reports the thermal modeling and characterization of a thyristor. The thyristor is used in a 6.5-MW generator excitation bridge. Temperature measurements are performed using fiber Bragg grating (FBG) sensors. These sensors have the benefits of being totally passive and immune to electromagnetic interference and also multiplexed in a single fiber. The thyristor thermal model consists of a second order equivalent electric circuit, and its power losses lead to an increase in temperature, while the losses are calculated on the basis of the excitation current in the generator. Six multiplexed FBGs are used to measure temperature and are embedded to avoid the effect of the strain sensitivity. The presented results show a relationship between field current and temperature oscillation and prove that this current can be used to determine the thermal model of a thyristor. The thermal model simulation presents an error of 1.5 °C, while the FBG used allows for the determination of the thermal behavior and the field current dependence. Since the temperature is a function of the field current, the corresponding simulation can be used to estimate the temperature in the thyristors. PMID:25198007

  8. Fiber Bragg Grating Temperature Sensors in a 6.5-MW Generator Exciter Bridge and the Development and Simulation of Its Thermal Model

    Directory of Open Access Journals (Sweden)

    Kleiton de Morais Sousa

    2014-09-01

    Full Text Available This work reports the thermal modeling and characterization of a thyristor. The thyristor is used in a 6.5-MW generator excitation bridge. Temperature measurements are performed using fiber Bragg grating (FBG sensors. These sensors have the benefits of being totally passive and immune to electromagnetic interference and also multiplexed in a single fiber. The thyristor thermal model consists of a second order equivalent electric circuit, and its power losses lead to an increase in temperature, while the losses are calculated on the basis of the excitation current in the generator. Six multiplexed FBGs are used to measure temperature and are embedded to avoid the effect of the strain sensitivity. The presented results show a relationship between field current and temperature oscillation and prove that this current can be used to determine the thermal model of a thyristor. The thermal model simulation presents an error of 1.5 °C, while the FBG used allows for the determination of the thermal behavior and the field current dependence. Since the temperature is a function of the field current, the corresponding simulation can be used to estimate the temperature in the thyristors.

  9. Design of a Label-Free, Distributed Bragg Grating Resonator Based Dielectric Waveguide Biosensor

    Directory of Open Access Journals (Sweden)

    Florian Kehl

    2015-01-01

    Full Text Available In this work, we present a resonant, dielectric waveguide device based on distributed Bragg gratings for label-free biosensing applications. The refractive index sensitive optical transducer aims at improving the performance of planar waveguide grating sensor systems with limited Q-factor and dynamic range by combing the advantages of resonant cavities, such as a multitude of resonance peaks with high finesse, with the manageable complexity of waveguide grating couplers. The general sensor concept is introduced and supported by theoretical considerations as well as numerical simulations based on Coupled Mode Theory. In contrast to a single Bragg grating reflector, the presented Fabry-Pérot type distributed Bragg resonator exhibits an extended measurement range as well as relaxed fabrication tolerances. The resulting, relatively simple sensor structure can be fabricated with standard lithographic means and is independent of expensive light-sources and/or detectors, making an affordable but sensitive device, potentially suitable for point-of-care applications.

  10. Longitudinal coupling effect in microfiber Bragg gratings

    Science.gov (United States)

    Zhao, Ping; Zhang, Jihua; Wang, Guanghui; Jiang, Meng; Ping Shum, Perry; Zhang, Xinliang

    2012-10-01

    We theoretically present longitudinal coupling effect (LCE) in air-cladding microfiber Bragg gratings (MFBGs). Distinct from conventional weakly-guiding optical fibers, large longitudinal electric field (Ez) exists in wavelength-scale microfibers. Due to LCE, MFBG reflectivity can be reduced by more than 30% within the band-gap and the full width at half maximum (FWHM) is obviously narrowed. This theoretical analytical work is instructive to precisely design and fabricate MFBGs that are promising in the areas of optical sensing and nanophotonics.

  11. Fiber Bragg grating hydrophone with high sensitivity

    Institute of Scientific and Technical Information of China (English)

    Wentao Zhang; Yuliang Liu; Fang Li

    2008-01-01

    A fiber Bragg grating (FBG) hydrophone with high sensitivity was demonstrated. This hydrophone used a rubber diaphragm and a copper hard core as the sensing element. To compensate the hydrostatic pressure,a capillary tube was fixed at the end of the hydrophone. Theoretical analysis of the acoustic pressuresensitivity was given in this letter. Experiments were carried out to test the frequency response of the hydrophone. The result shows that when the Young's modulus of the diaphragm is higher, a flatter frequency response will be obtained.

  12. Modeling Component-based Bragg gratings Application: tunable lasers

    Directory of Open Access Journals (Sweden)

    Hedara Rachida

    2011-09-01

    Full Text Available The principal function of a grating Bragg is filtering, which can be used in optical fibers based component and active or passive semi conductors based component, as well as telecommunication systems. Their ideal use is with lasers with fiber, amplifiers with fiber or Laser diodes. In this work, we are going to show the principal results obtained during the analysis of various types of grating Bragg by the method of the coupled modes. We then present the operation of DBR are tunable. The use of Bragg gratings in a laser provides single-mode sources, agile wavelength. The use of sampled grating increases the tuning range.

  13. Microfiber-Based Bragg Gratings for Sensing Applications: A Review

    Directory of Open Access Journals (Sweden)

    Jun-Long Kou

    2012-06-01

    Full Text Available Microfiber-based Bragg gratings (MFBGs are an emerging concept in ultra-small optical fiber sensors. They have attracted great attention among researchers in the fiber sensing area because of their large evanescent field and compactness. In this review, the basic techniques for the fabrication of MFBGs are introduced first. Then, the sensing properties and applications of MFBGs are discussed, including measurement of refractive index (RI, temperature, and strain/force. Finally a summary of selected MFBG sensing elements from previous literature are tabulated.

  14. Application of the Transmission Bragg Gratings for Vibration Monitoring

    CERN Document Server

    Tikhonov, E A

    2010-01-01

    It is shown that the optical-electronic system consisted of the transmission Bragg grating, a laser and the intermediate sensitive to the vibrations mirror can detect the vibrations, when touched by them laser beam scan will exceed the angular divergence of the beam. The mathematical model of the sensor of the vibrations presented in the form of Taylor series describes the system response taking into account the operating point, in particular, describes the effect of the doubling of the modulation frequency response relative to the frequency of acting vibrations.

  15. Measuring vibration by using fiber Bragg grating and demodulating it by blazed grating

    Institute of Scientific and Technical Information of China (English)

    Xiaojin Guo(郭晓金); Zongmin Yin(殷宗敏); Ning Song(宋宁)

    2004-01-01

    A method of measuring vibration by using fiber Bragg grating (FBG) and demodulating the spectrum by blazed grating is introduced. The sensor system is made of a simple supported beam with a FBG adhered to its upper surface. A blazed grating is used to demodulate the changing spectrum that is got from the sensor system, and a line charge-coupled device (CCD) is used to accept the diffraction spectrum.Through analyzing the number of the CCD's pixels, we can get the amplitude of vibration and the change of the temperature. The experimental results show that the vibration amplitude of the exciter matches the detected signal under the stable frequency. The temperature shift and vibration signal are also successfully separated.

  16. First order Bragg grating filters in silicon on insulator waveguides

    Science.gov (United States)

    Waugh, Peter Michael

    2008-08-01

    The subject of this project is the design; analysis, fabrication and characterisation of first order Bragg Grating optical filters in Silicon-on-Insulator (SOI) planar waveguides. It is envisaged that this work will result in the possibility of Bragg Grating filters for use in Silicon Photonics. It is the purpose of the work to create as far as is possible flat surface waveguides so as to facilitate Thermo-Optic tuning and also the incorporation into rib-waveguide Silicon Photonics. The spectral response of the shallow Bragg Gratings was modelled using Coupled Mode Theory (CMT) by way of RSoft Gratingmod TM. Also the effect of having a Bragg Grating with alternate layers of refractive index of 1.5 and 3.5 was simulated in order to verify that Silica and Silicon layered Bragg Gratings could be viable. A series of Bragg Gratings were patterned on 1.5 micron SOI at Philips in Eindhoven, Holland to investigate the variation of grating parameters with a) the period of the gratings b) the mark to space ratio of the gratings and c) the length of the region converted to Bragg Gratings (i.e. the number of grating period repetitions). One set of gratings were thermally oxidised at Philips in Eindhoven and another set were ion implanted with Oxygen ions at the Ion Beam Facility, University of Surrey, England. The gratings were tested and found to give transmission minima at approximately 1540 nanometres and both methods of creating flat surfaces were found to give similar minima. Atomic Force Microscopy was applied to the grating area of the as-implanted samples in the Advanced Technology Institute, University of Surrey, which were found to have surface undulations in the order of 60 nanometres.

  17. The use of fiber Bragg grating sensors in biomechanics and rehabilitation applications: the state-of-the-art and ongoing research topics.

    Science.gov (United States)

    Al-Fakih, Ebrahim; Abu Osman, Noor Azuan; Mahamd Adikan, Faisal Rafiq

    2012-01-01

    In recent years, fiber Bragg gratings (FBGs) are becoming increasingly attractive for sensing applications in biomechanics and rehabilitation engineering due to their advantageous properties like small size, light weight, biocompatibility, chemical inertness, multiplexing capability and immunity to electromagnetic interference (EMI). They also offer a high-performance alternative to conventional technologies, either for measuring a variety of physical parameters or for performing high-sensitivity biochemical analysis. FBG-based sensors demonstrated their feasibility for specific sensing applications in aeronautic, automotive, civil engineering structure monitoring and undersea oil exploration; however, their use in the field of biomechanics and rehabilitation applications is very recent and its practicality for full-scale implementation has not yet been fully established. They could be used for detecting strain in bones, pressure mapping in orthopaedic joints, stresses in intervertebral discs, chest wall deformation, pressure distribution in Human Machine Interfaces (HMIs), forces induced by tendons and ligaments, angles between body segments during gait, and many others in dental biomechanics. This article aims to provide a comprehensive overview of all the possible applications of FBG sensing technology in biomechanics and rehabilitation and the status of ongoing researches up-to-date all over the world, demonstrating the FBG advances over other existing technologies. PMID:23201977

  18. The Use of Fiber Bragg Grating Sensors in Biomechanics and Rehabilitation Applications: The State-of-the-Art and Ongoing Research Topics

    Directory of Open Access Journals (Sweden)

    Faisal Rafiq Mahamd Adikan

    2012-09-01

    Full Text Available In recent years, fiber Bragg gratings (FBGs are becoming increasingly attractive for sensing applications in biomechanics and rehabilitation engineering due to their advantageous properties like small size, light weight, biocompatibility, chemical inertness, multiplexing capability and immunity to electromagnetic interference (EMI. They also offer a high-performance alternative to conventional technologies, either for measuring a variety of physical parameters or for performing high-sensitivity biochemical analysis. FBG-based sensors demonstrated their feasibility for specific sensing applications in aeronautic, automotive, civil engineering structure monitoring and undersea oil exploration; however, their use in the field of biomechanics and rehabilitation applications is very recent and its practicality for full-scale implementation has not yet been fully established. They could be used for detecting strain in bones, pressure mapping in orthopaedic joints, stresses in intervertebral discs, chest wall deformation, pressure distribution in Human Machine Interfaces (HMIs, forces induced by tendons and ligaments, angles between body segments during gait, and many others in dental biomechanics. This article aims to provide a comprehensive overview of all the possible applications of FBG sensing technology in biomechanics and rehabilitation and the status of ongoing researches up-to-date all over the world, demonstrating the FBG advances over other existing technologies.

  19. Femtosecond laser inscription of Bragg and complex gratings in coated and encapsulated silica and low-loss polymer optical fibers

    Science.gov (United States)

    Kalli, Kyriacos; Lacraz, Amedee; Polis, Michael; Othonos, Andreas

    2015-09-01

    The development of wavelength filters, such as Bragg and superstructure gratings in glass and polymer optical fibers, using a femtosecond laser is reported. By using a femtosecond laser operating in the green, which offers greater inscription efficiency, we demonstrate the reliable inscription of Bragg and superstructure gratings in coated silica and low-loss CYTOP polymer optical fibers. We employ line by line and point by point inscription methods, allowing for multiple and overlapping gratings in the fiber core. Moreover, we demonstrate a novel fibre Bragg grating inscription technique to modify and add versatility to an existing, encapsulated optical fiber pressure sensor.

  20. Remote (250 km Fiber Bragg Grating Multiplexing System

    Directory of Open Access Journals (Sweden)

    Manuel Lopez-Amo

    2011-09-01

    Full Text Available We propose and demonstrate two ultra-long range fiber Bragg grating (FBG sensor interrogation systems. In the first approach four FBGs are located 200 km from the monitoring station and a signal to noise ratio of 20 dB is obtained. The second improved version is able to detect the four multiplexed FBGs placed 250 km away, offering a signal to noise ratio of 6–8 dB. Consequently, this last system represents the longest range FBG sensor system reported so far that includes fiber sensor multiplexing capability. Both simple systems are based on a wavelength swept laser to scan the reflection spectra of the FBGs, and they are composed by two identical-lengths optical paths: the first one intended to launch the amplified laser signal by means of Raman amplification and the other one is employed to guide the reflection signal to the reception system.

  1. The Use of Fiber Bragg Grating Sensors in Biomechanics and Rehabilitation Applications: The State-of-the-Art and Ongoing Research Topics

    OpenAIRE

    Faisal Rafiq Mahamd Adikan; Ebrahim Al-Fakih; Noor Azuan Abu Osman

    2012-01-01

    In recent years, fiber Bragg gratings (FBGs) are becoming increasingly attractive for sensing applications in biomechanics and rehabilitation engineering due to their advantageous properties like small size, light weight, biocompatibility, chemical inertness, multiplexing capability and immunity to electromagnetic interference (EMI). They also offer a high-performance alternative to conventional technologies, either for measuring a variety of physical parameters or for performing high-sensiti...

  2. Fiber Bragg grating sensors for strain changes measurements at volcanic sites (MED-SUV project; WP 2; Sub-Task 2.2.2)

    Science.gov (United States)

    Sorrentino, Fiodor; Beverini, Nicolò; Calamai, Massimo; Carbone, Daniele; Fotino, Nicoletta; Francesconi, Francesco; Gambino, Salvatore; Grassi, Renzo; Messin, Alfio Alex; Maccioni, Enrico; Morganti, Mauro

    2015-04-01

    Stress and strain changes at volcanic areas are recognized among the best indicators of changes in the activity of the system, and its possible evolution towards critical stages. Depending on their time evolution, stress and strain changes have been the focus of either geodetic (static changes) or seismological (dynamical changes) studies. In volcano geodesy, encouraging results have been obtained though borehole strain-meters. However, they are not easy to install and involve high costs. Therefore, the near future of strain observations at volcanoes depends on the development of broad-band sensors which are low-cost and easy to install, even in the form of dense arrays. Advancements in opto-electronics have allowed the development of low-cost sensors, reliable, rugged and compact, which are particularly suitable for on-field application. In the framework of WP 2 (New monitoring and Observing systems) of the MED-SUV project, the sub-task 2.2 involves the development of strain sensors based on the fiber Bragg grating (FBG) technology. In comparison with previous implementation of the FBG technology to study rock deformations, the system that is being developed within MED-SUV is expected to offer a significantly higher resolution and accuracy in static measurements. Moreover, a careful study is being carried out in order to obtain a smooth dynamic response up to 100 Hz, thus allowing the observation of seismic waves. Finally, the system under development will allow multi-axial strain sensing. The system performances are tailored to suit the requirements of volcano monitoring, with special attention to the trade-off between resolution and cost, and with special care to power consumption. Here we present the results of a field campaign with a preliminary, single-axis FBG strain sensor prototype on Etna, which was carried out in order to check the system performances in out-of-the-lab conditions and in the hostile volcanic environment (lack of mains electricity for

  3. Novel Distributed Fiber Bragg Grating Sensing System Based on M-Z Interferometer

    Institute of Scientific and Technical Information of China (English)

    WU Guo-qing; BI Wei-hong; LI Hong

    2005-01-01

    One of the problems in using grating sensors is how to measure a small Bragg wavelength shift accurately. Nowadays demodulation techniques are mainly based on the edge filter, tunable filter, or interferometric scanning methods. Interferometric demodulation is widely accepted as the technology which can provide the high sensitivity. An interrogation system using the interferometric scanning method is presented, in which an unbalanced fiber M-Z interferometer is used as the wavelength scanner for temperature measurement. A novel fiber Bragg grating sensor system based on M-Z interferometric demodulation technique is presented in this paper. The temperature sensitivity measured in the experiment is almost consistent with that obtained from the theoretic calculation.

  4. Analytical investigation of a novel interrogation approach of fiber Bragg grating sensors using Optical Frequency Domain Reflectometry

    Science.gov (United States)

    Yüksel, Kivilcim; Pala, Deniz

    2016-06-01

    This work presents a novel approach in interrogating Polarization Dependent Loss (PDL) of cascaded identical FBGs using Optical Frequency Domain Reflectometer (OFDR). The fundamentals of both polarisation properties of uniform FBGs and polarisation-sensitive OFDR are explained and the benefits of this novel approach in measuring transversal load are discussed. The numerical programs computing the spectral evolution of PDL of the FBGs in the array as a function of grating parameters (grating length and birefringence) are presented. Our simulation results show an excellent agreement with the previously reported simulation (and experimental) results in the literature obtained on a single FBG by using classical state-of-the-art measurement techniques. As an envisaged application, the proposed system shows the feasibility of measuring the residual stresses during manufacturing process of composite materials which is not straightforward by amplitude spectrum measurements and/or considering only the axial strains.

  5. Writing Bragg Gratings in Multicore Fibers.

    Science.gov (United States)

    Lindley, Emma Y; Min, Seong-Sik; Leon-Saval, Sergio G; Cvetojevic, Nick; Lawrence, Jon; Ellis, Simon C; Bland-Hawthorn, Joss

    2016-01-01

    Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers. PMID:27167576

  6. Fiber Bragg gratings in the radiation environment: Change under the influence of radiolytic hydrogen

    Science.gov (United States)

    Butov, Oleg V.; Golant, Konstantin M.; Shevtsov, Igor'A.; Fedorov, Artem N.

    2015-08-01

    The change of the transmission spectra of fiber Bragg gratings written in the optical fibers, whose silica cores are doped with either germanium or nitrogen, is studied experimentally under the influence of gamma-radiation. The transmission spectra in the neighborhood of the resonance (Bragg) wavelengths were regularly recorded "in-situ" in the course of irradiation during 24 days. For this purpose, uncoated gratings were placed in a pool near the spent fuel rods of a nuclear reactor. The fibers with the gratings written in them were in immediate contact with water. The estimated total absorbed radiation dose of the fibers is approximately 5 MGy. Molecular hydrogen, which is produced by radiolysis of water and penetrates into the core of silica fiber, is found to interact with the defects of Ge-doped silica induced by gamma-radiation, thereby causing a strong impact on the parameters of the spectrum of the Bragg gratings. On the contrary, in the case of gratings inscribed in N-doped silica fibers, the hydrogen molecules interact with defects induced in the course of laser UV exposure during the grating writing only. The possible subsequent formation of additional defects in N-doped silica under the influence of gamma-radiation has no substantial impact on the transmission spectra of Bragg gratings, which remained stable. The obtained results suggest that a small amount of molecular hydrogen resided in the fiber core is the main source of radiation instability of Ge-doped fiber Bragg grating sensors in radiation environments. These hydrogen molecules can remain in the Bragg gratings, in particular, after the inscription process in the hydrogen-loaded fibers.

  7. Fiber Bragg gratings in the radiation environment: Change under the influence of radiolytic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Butov, Oleg V., E-mail: obutov@mail.ru; Golant, Konstantin M. [Kotel' nikov Institute of Radio-Engineering and Electronics of RAS, 11-7 Mokhovaya Str., Moscow 125009 (Russian Federation); Shevtsov, Igor' A.; Fedorov, Artem N. [Prolog LLC, PO Box 3007, Obninsk, the Kaluga Region 249033 (Russian Federation)

    2015-08-21

    The change of the transmission spectra of fiber Bragg gratings written in the optical fibers, whose silica cores are doped with either germanium or nitrogen, is studied experimentally under the influence of gamma-radiation. The transmission spectra in the neighborhood of the resonance (Bragg) wavelengths were regularly recorded “in-situ” in the course of irradiation during 24 days. For this purpose, uncoated gratings were placed in a pool near the spent fuel rods of a nuclear reactor. The fibers with the gratings written in them were in immediate contact with water. The estimated total absorbed radiation dose of the fibers is approximately 5 MGy. Molecular hydrogen, which is produced by radiolysis of water and penetrates into the core of silica fiber, is found to interact with the defects of Ge-doped silica induced by gamma-radiation, thereby causing a strong impact on the parameters of the spectrum of the Bragg gratings. On the contrary, in the case of gratings inscribed in N-doped silica fibers, the hydrogen molecules interact with defects induced in the course of laser UV exposure during the grating writing only. The possible subsequent formation of additional defects in N-doped silica under the influence of gamma-radiation has no substantial impact on the transmission spectra of Bragg gratings, which remained stable. The obtained results suggest that a small amount of molecular hydrogen resided in the fiber core is the main source of radiation instability of Ge-doped fiber Bragg grating sensors in radiation environments. These hydrogen molecules can remain in the Bragg gratings, in particular, after the inscription process in the hydrogen-loaded fibers.

  8. Research of fiber Bragg grating geophone based on cantilever beam

    Science.gov (United States)

    Wang, Liang; Chen, Shao-hua; Tao, Guo; Lu, Gui-wu; Zhao, Kun

    2009-07-01

    Along with the development of seismic exploration, the demand of frequency, dynamic range, precision and resolution ration is increased. However, the traditional geophone has disadvantages of narrower bandwidth, lower dynamic range and resolution, and cannot meet the new needs of seismic exploration. Geophone technology is a choke point, which constrains the development of petroleum prospecting in recent years. Fiber Bragg Grating seism demodulation technology is the newest kind of seism demodulation technology. The sensing probe of the Fiber Bragg Grating geophone is made up of Fiber Bragg Gating. The information which it collects is embodied by wavelength. The modulation-demodulation is accomplished by Fiber Bragg Gating geophone directly. In this paper, we design different size Fiber Bragg Grating geophones based on the transmission properties of Fiber Bragg Grating and cantilever beam method. Beryllium bronze and stainless steel are chosen as the elastic beam and shell materials, respectively. The parameters such as response function and sensitivity are given theoretically. In addition, we have simulated the transmission characteristics of Fiber Bragg Grating geophone by virtue of finite element analysis. The influences of wavelength, mass block, fiber length on the characteristics of geophones are discussed in detail, and finally the appropriate structural parameters are presented.

  9. Optical fibre Bragg grating recorded in TOPAS cyclic olefin copolymer

    DEFF Research Database (Denmark)

    Johnson, I.P.; Yuan, Scott Wu; Stefani, Alessio;

    2011-01-01

    A report is presented on the inscription of a fibre Bragg grating into a microstructured polymer optical fibre fabricated from TOPAS cyclic olefin copolymer. This material offers two important advantages over poly (methyl methacrylate), which up to now has formed the basis for polymer fibre Bragg...

  10. Numerical Analysis of Fiber Bragg Grating and Long Period Fiber Grating Undergoing Linear and Quadratic Temperature Change

    Institute of Scientific and Technical Information of China (English)

    YUAN Yinquan; DING Liyun

    2009-01-01

    The coupled-mode equations for fiber Bragg grating(FBG)and long period fiber grating(LPFG)undergoing linear and quadratic temperature change were given.The effects of tem-perature gradient and quadratic temperature change on the reflectivity spectrum of fiber Braggs grating and the transmission spectrum of long period fiber grating were investigated using the numerical simulation,and the dependence relationships of the central wavelength shift,the full-width-at-half-maximum,and the peak intensity upon temperature gradient were also obtained.These relation-ships may be used to design a novel fiber optical sensor which can simultaneously measure the tem-perature and temperature gradient.

  11. Dynamic interrogator for elastic wave sensing using Fabry Perot filters based on fiber Bragg gratings.

    Science.gov (United States)

    Harish, Achar V; Varghese, Bibin; Rao, Babu; Balasubramaniam, Krishnan; Srinivasan, Balaji

    2015-07-01

    Use of in-fiber Fabry-Perot (FP) filters based on fiber Bragg gratings as both sensor as well as an interrogator for enhancing the detection limit of elastic wave sensing is investigated in this paper. The sensitivity of such a demodulation scheme depends on the spectral discrimination of the sensor and interrogator gratings. Simulations have shown that the use of in-fiber FP filters with high finesse provide better performance in terms of sensitivity compared to the demodulation using fiber Bragg gratings. Based on these results, a dynamic interrogator capable of sensing acoustic waves with amplitude of less than 1 micro-strain over frequencies of 10 kHz to several 100 kHz has been implemented. Frequency response of the fiber Bragg gratings in the given experimental setup has been compared to that of the conventional piezo sensors demonstrating that fiber Bragg gratings can be used over a relatively broad frequency range. Dynamic interrogator has been packaged in a compact box without any degradation in its performance.

  12. Real Time Mode Sensing and Attitude Control of Flexible Launch Vehicle with Fiber Bragg Grating Sensor Array

    Science.gov (United States)

    Jiang, Hao

    Missiles and launch vehicles are typically slender in shape to reduce aerodynamic drag. Bending vibration occurs when a flying object with a large slenderness ratio performs pitch or yaw commands. The Inertial Measurement Unit (IMU) onboard measures the attitude and angular velocities of the deflected body as well as the rigid body motion, and in turn feeds these signals back into the control loop. Feedback of vibrating information degrades the control system stability and in the worst cases makes the system unstable. These effects become more significant as the slenderness ratio of the rocket increases. Another important challenge in launch vehicle control is created by the time-varying mass and inertia, as well as the consequent changes in modal frequencies and modal shapes of the structure as propellant is exhausted. This dissertation presents a method to correct the IMU sensors measurements with real time vibrating deflection measured by FBG sensors which have negligible mass penalty. Compared to notch filters and observers, unexpected errors induced by frequency variations, mode truncations, and un-modeled aerodynamics induced by deformation are avoided by using FBG corrected measurements. To deal with the time varying modal properties, a novel approach for the real-time estimation of mode shapes on a variable mass structure using FBG sensors is also presented in this dissertation. The method is validated by comparing estimated modal shapes to both numerical predictions and experiments on a vertical cantilever beam in which a step change in mass is introduced. The results show that the first three mode shapes of the beam can be estimated in real time using strain measurements from a FBG sensor array sampled at 1 kHz. A trajectory control system of a vertical cantilever beam is used in this dissertation to validate the method based on real-time mode sensing and FBG correction on IMU sensors. The flexible rocket dynamics and the prospective applications of this

  13. 光纤光栅传感器在舰船结构健康监测中的应用%Studying the application of fiber Bragg grating sensor on ship structures health monitoring

    Institute of Scientific and Technical Information of China (English)

    吴晶; 吴晗平; 黄俊斌; 顾宏灿

    2014-01-01

    The fiber grating sensor is a novel sensor and has many strong points to the old sensor, such as small size, high sensitivity, high temperature resistance and corrosion resistance, strong anti-disturbance of electromagnetism, and can form a large scale distributed sensor net. So it becomes research spot in the field of structure health monitoring. This paper introduces the characteristics and the theory of fiber Bragg grating sensor. Review the development and applications of fiber Bragg grating sensor on ship structure health monitoring. Discuss the compose of ship structure health monitoring and the key content of studying.%光纤光栅传感器是一种新型传感器,相对传统的传感器具有体积小、灵敏度高、耐高温、耐腐蚀、抗电磁干扰,能组建大规模准分布式传感网络等特点,近年来已成为结构健康检测领域中的研究热点。本文介绍光纤光栅传感器( FBG)的特点和工作原理,综述国内外光纤光栅传感器在舰船结构健康监测领域的研究现状,探讨基于光纤光栅传感器的舰船结构健康监测系统的组成和主要研究内容。

  14. Thermally tunable integrated planar Bragg-grating stabilized diode laser

    Science.gov (United States)

    Lynch, S. G.; Gates, J. C.; Berry, S. A.; Holmes, C.; Smith, P. G. R.

    2015-03-01

    A pair of external cavity diode lasers are fabricated using an integrated planar Bragg grating. The planar waveguide and Bragg reflector is UV-written within a glass-on-silicon chip. Intensity isolated, continuous wavelength tuning at > 1kHz modulation rate is acheived using micro-heating elements fabricated directly over the Bragg grating. Low RIN (<140dB) and low linewidth (δν ~ 200 kHz) operation is found using a heterodyne measurement. We demonstrate the lasers operating in phase-locked loop configuration where one laser is frequency-offset locked to the other.

  15. Compact Bragg Gratings for Long-Range Surface Plasmon Polaritons

    DEFF Research Database (Denmark)

    Boltasseva, Alexandra; Bozhevolnyi, Sergey I; Nikolajsen, Thomas;

    2006-01-01

    By introducing periodic thickness-modulation of thin metal stripes embedded in a dielectric, we realize compact and efficient Bragg gratings for long-range surface plasmon polaritons (LR-SPPs) operating around 1550 nm. We measure reflection and transmission spectra of the gratings having different...

  16. Birefringent Bragg Gratings in Highly-Nonlinear Photonic Crystal Fiber

    Institute of Scientific and Technical Information of China (English)

    Kevin Cook; John Canning; John Holdsworth

    2008-01-01

    Efficient writing of Bragg gratings in 12-ring highly-nonlinear photonic crystal fibers is described. Experimental and numerical investigations are performed to reveal the optimum angle for coupling UV writing light to the core. Furthermore, we show that the formation of a strongly briefringent grating is at a particular angle of orientation.

  17. Three-hole microstructured optical fiber for efficient Fiber Bragg Grating refractometer

    OpenAIRE

    Phan Huy, Minh Châu; Laffont, Guillaume; Dewynter, Véronique; Ferdinand, Pierre; Roy, Philippe; Auguste, Jean-Louis; Pagnoux, Dominique; Blanc, Wilfried; Dussardier, Bernard

    2007-01-01

    International audience We present a photosensitive three-hole microstructured optical fiber specifically designed to improve the refractive index sensitivity of a standard Fiber Bragg Grating (FBG) sensor photowritten in the suspended Ge-doped silica core. We describe the specific photowriting procedure used to realize gratings in such a fiber. We then determine their spectral sensitivity to the refractive index changes of material filling the holes surrounding the core. The sensitivity is...

  18. Using Dual-wavelength Fiber Bragg Gratings for Temperature and Strain Sensing at Cryogenic Temperature

    Science.gov (United States)

    Wu, Meng-Chou; Prosser, William H.; Rogowski, Robert S.; DeHaven, Stanton L.

    2003-01-01

    By using dual-wavelength fiber-optic Bragg gratings, a new technique has been developed for sensing both temperature and strain simultaneously in cryogenic temperature range. Two Bragg gratings with different wavelengths were inscribed at the same location in an optical fiber to form a dual-wavelength sensor. By measuring the wavelength shifts that resulted from the fiber being subjected to different temperatures and strains, the wavelength-dependent thermo-optic coefficients and photoelastic coefficients of the fiber were determined. These coefficients were used to construct the elements of the K matrix, which enables to determine inversely the strain and temperature changes by measuring the wavelength shifts of the dual-wavelength Bragg grating. In this study, measurements were made over the temperature range from room temperature down to about 10 K, addressing much of the low temperature range of cryogenic tanks. A structure transition of the optical fiber during the temperature change was found from about 70 K to 140 K. This transition caused splitting of the waveforms characterizing the Bragg gratings, and the determination of wavelength shifts was consequently complicated. Several alternatives are proposed to resolve this problem. The effectiveness and sensitivities of these measurements in different temperature ranges are discussed. The separation of two wavelengths for the dual-wavelength Bragg grating has been widened to increase the sensitivities of measurement; however, this separation can still be covered in the scanning range from single scanning laser.

  19. Fabrication of the Long Bragg Grating by Excimer Laser Micro Machining with High-Precision Positioning XXY Platform

    Directory of Open Access Journals (Sweden)

    Jian-Zhong Wu

    2014-03-01

    Full Text Available With the advancement of technology, the application of fiber Bragg grating is widely used as a Bragg grating sensor. Fiber Bragg grating is fabrication using excimer laser machining with the phase masker. The grating length is decided by the width of laser beam. In this paper, we proposed fabrication of the long Bragg grating by excimer Laser micro machining with a high-precision positioning XXY platform. The high-precision positioning XXY platform plays an important role for long FBG. It needs seriously to combine three short FBGs. Therefore, we can obtain a long FBG with 15mm length. This method can provide a solution to fabricate long FBG by using cheap laser with high-precision positioning XXY platform.

  20. Miniature and low cost fiber bragg grating interrogator for structural monitoring in nano-satellites

    NARCIS (Netherlands)

    Toet, P.M.; Hagen, R.A.J.; Hakkesteegt, H.C.; Lugtenburg, J.; Maniscalco, M.P.

    2014-01-01

    In this paper we present a newly developed Fiber Optic measurement system, consisting of Fiber Bragg Grating (FBG) sensors and an FBG interrogator. The development of the measuring system is part of the PiezoElectric Assisted Smart Satellite Structure (PEASSS) project, which was initiated at the beg

  1. Perturbative modeling of Bragg-grating-based biosensors in photonic-crystal fibers

    DEFF Research Database (Denmark)

    Burani, Nicola; Lægsgaard, Jesper

    2005-01-01

    We present a modeling study carried out to support the design of a novel, to our knowledge, kind of photonic-crystal fiber (PCF)-based sensor. This device, based on a PCF Bragg grating, detects the presence of selected single-stranded DNA molecules, hybridized to a biofilm in the air holes of the...

  2. Simulation of Novel Tunable Nonlinear Chirped Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-min; YU Zhong-yuan; ZHANG Xiao-guang; YU Li; YANG Bo-jun

    2003-01-01

    A novel tunable chirped fiber Bragg grating technology is proposed and simulated numerically by Matlab. If we adhere a uniform fiber grating with super magnetostrictive film and expose them in a non-uniform magnetic field, the period of the grating can be changed with the strain imposed on it by the magnetostrictive effect .The chirped characteristics can be tuned by changing the magnetic filed which is very flexible in designing.

  3. Simultaneous Temperature and Strain Sensing for Cryogenic Applications Using Dual-Wavelength Fiber Bragg Gratings

    Science.gov (United States)

    Wu, Meng-Chou; Prosser, William H.

    2003-01-01

    A new technique has been developed for sensing both temperature and strain simultaneously by using dual-wavelength fiber-optic Bragg gratings. Two Bragg gratings with different wavelengths were inscribed at the same location in an optical fiber to form a sensor. By measuring the wavelength shifts that resulted from the fiber being subjected to different temperatures and strains, the wavelength-dependent thermo-optic coefficients and photoelastic coefficients of the fiber were determined. This enables the simultaneous measurement of temperature and strain. In this study, measurements were made over the temperature range from room temperature down to about 10 K, addressing much of the low temperature range of cryogenic tanks. A structure transition of the optical fiber during the temperature change was found. This transition caused splitting of the waveforms characterizing the Bragg gratings, and the determination of wavelength shifts was consequently complicated. The effectiveness and sensitivities of these measurements in different temperature ranges are also discussed.

  4. Simultaneous 2D Strain Sensing Using Polymer Planar Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Manuel Rosenberger

    2015-02-01

    Full Text Available We demonstrate the application of polymer planar Bragg gratings for multi-axial strain sensing and particularly highlight simultaneous 2D strain measurement. A polymer planar Bragg grating (PPBG fabricated with a single writing step in bulk polymethylmethacrylate is used for measuring both tensile and compressive strain at various angles. It is shown that the sensitivity of the PPBG strongly depends on the angle between the optical waveguide into which the grating is inscribed and the direction along which the mechanical load is applied. Additionally, a 2D PPBG fabricated by writing two Bragg gratings angularly displaced from each other into a single polymer platelet is bonded to a stainless steel plate. The two reflected wavelengths exhibit different sensitivities while tested toward tensile and compressive strain. These characteristics make 2D PPBG suitable for measuring multi-axial tensile and compressive strain.

  5. Simultaneous Strain and Temperature Measurement Using Single High-duty-cycle Sampled Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A novel and simple fiber grating sensor based on high-duty-cycle sample fiber Bragg grating is proposed and demonstrated experimentally. This type of sensor can measure strain and temperature simultaneously with merits of low cost, high sensitivity and immunity to electro- magnetic interference. The sensor has an accuracy of 20με and 0.8℃ over a strain range of 500~1500με and a temperature range of 5~36℃ under experimental conditions.

  6. Medición de microdeformaciones en losas viales usando sensores de redes de Braggen fibras ópticas Microdeformation measurement of concrete roadway slabs using fiber Bragg gratings

    Directory of Open Access Journals (Sweden)

    Francisco Javier Vélez Hoyos

    2010-06-01

    Full Text Available En este trabajo se presenta un método no invasivo para la medición de microdeformaciones en estructuras de concreto usando sensores de redes de Bragg en fibras ópticas adheridos a su superficie. Se realizan mediciones en losas viales de concreto bajo una carga estática de 10 kN, encontrándose una relación aproximada de 2 : 1 entre la deformación registrada por los sensores y los valores arrojados por una simulación computacional con el método de elementos finitos. Se propone el uso de estos sensores para el monitoreo estructural de losas en una malla vial con sensores distribuidos y multiplexados por longitud de onda. Este es el primer reporte en Colombia de medición de deformación de losas viales usando sensores de fibra óptica.This work shows a non–invasive method for micro–deformation measurements of concrete structures using Bragg grating sensors in optical fibers adhered to the surface. Measurements on roadway slabs under a 10 kN static load are made, finding an approximated ratio of 2 : 1 between the deformation registered by the sensors and the values from a computational simulation with the finite element method. We propose the use of these sensors for slab structural monitoring in a road network employing distributed and wavelength multiplexed sensors. This is a first report in Colombia of roadway slabs microdeformation measurement using fiber optic sensors.

  7. Photonic scanning receiver using an electrically tuned fiber Bragg grating.

    Science.gov (United States)

    Rugeland, P; Yu, Z; Sterner, C; Tarasenko, O; Tengstrand, G; Margulis, W

    2009-12-15

    A 5-cm-long electrically tuned fiber Bragg grating is used to filter a microwave signal on an optical carrier at 1.55 mum. A chirped distributed-feedback structure is employed, with a transmission bandwidth of 54 MHz and relative optical carrier rejection of >30 dB for rf frequencies >2 GHz. The rapid monotonic sweep of the Bragg wavelength is translated into a fast-frequency sweep for rf analysis. PMID:20016616

  8. Metal-coated second-order fibre Bragg gratings produced by infrared femtosecond radiation for dual temperature and strain sensing

    Science.gov (United States)

    Chah, K.; Kinet, D.; Caucheteur, C.

    2016-05-01

    We report highly localized second-order fibre Bragg gratings at 1585 nm inscribed by point-by-point focused infrared femtosecond pulses. A thin gold coating deposited on the fibre outer surface at the grating location allows shielding the cladding mode resonances from the outer medium, so that they remain present in the transmitted amplitude spectrum. The Bragg resonance of the second-order grating is surrounded by high-order cladding mode resonances of the first-order grating. These cladding modes exhibit the same temperature sensitivity as the Bragg resonance (10.6 pm/°C) but high differential strain sensitivity (-0.55 pm/μepsilon versus 1.20 pm/μepsilon for the Bragg mode). Therefore, the conditioning of the matrix inversion as demodulation method is fully satisfied, yielding a new design of fibre sensor able to discriminate between temperature and strain, with an unprecedented sensitivity.

  9. Use of 3000 Bragg Grating Strain Sensors Distributed on Four Eight-meter Optical Fibers During Static Load Tests of a Composite Structure

    Science.gov (United States)

    Childers, Brooks A.; Froggatt, Mark E.; Allison, Sidney G.; Moore, Thomas C., Sr.; Hare, David A.; Batten, Christopher F.; Jegley, Dawn C.

    2001-01-01

    This paper describes the use of a fiber optic system to measure strain at thousands of locations along optical fibers where weakly reflecting Bragg gratings have been photoetched. The optical fibers were applied to an advanced composite transport wing along with conventional foil strain gages. A comparison of the fiber optic and foil gage systems used for this test will be presented including: a brief description of both strain data systems; a discussion of the process used for installation of the optical fiber; comparative data from the composite wing test; the processes used for the location and display of the high density fiber optic data. Calibration data demonstrating the potential accuracy of the fiber optic system will also be presented. The opportunities for industrial and commercial applications will be discussed. The fiber optic technique is shown to be a valuable augmentation to foil strain gages providing insight to structural behavior previously requiring reliance on modeling.

  10. High-strain fiber bragg gratings for structural fatigue testing of military aircraft

    Science.gov (United States)

    Davis, Claire; Tejedor, Silvia; Grabovac, Ivan; Kopczyk, James; Nuyens, Travis

    2012-09-01

    This paper reports on an experimental program of work which investigates the reliability, durability, and packaging of fiber Bragg gratings (FBGs) for application as distributed strain sensors during structural fatigue testing of military platforms. The influence of the FBG fabrication process on sensor reliability is investigated. In addition, methodologies for broad-area packaging and surface-mounting of FBG sensing arrays to defense platforms are developed and tested.

  11. Bragg gratings in index-guiding photonic crystal fibres

    DEFF Research Database (Denmark)

    Riishede, Jesper; Hougaard, Kristian G.; Libori, S.E. Barkou;

    2002-01-01

    A numerical investigation of coupling coefficients of Bragg-gratings in index-guiding photonic crystal fibres is presented. It is shown that index-guiding photonic crystal fibres have larger coupling coefficients for fibres with small core areas than step-index fibres.......A numerical investigation of coupling coefficients of Bragg-gratings in index-guiding photonic crystal fibres is presented. It is shown that index-guiding photonic crystal fibres have larger coupling coefficients for fibres with small core areas than step-index fibres....

  12. Analysis of transmission mode of a matched fiber Bragg grating interrogation scheme.

    Science.gov (United States)

    Wade, Scott A; Attard, Daniel P; Stoddart, Paul R

    2010-08-20

    A detailed investigation has been undertaken into the transmission mode of the matched fiber Bragg grating interrogation scheme with respect to its use in optical fiber sensor applications. Analytical and numerical models of the scheme have been developed. Experimental studies presented include the effect of the spectral characteristics of the gratings on system performance, results of strain and compression calibrations, a scheme to correct for intensity fluctuations, and the correction of temperature-induced shifts by collocating sensor and reference gratings. The results are in good agreement with a simplified model of the transmission mode. The analysis provides quantitative relationships between key sensor design parameters, such as sensitivity and measurement range as a function of grating bandwidth. PMID:20733619

  13. Solgel grating waveguides for distributed Bragg reflector lasers.

    Science.gov (United States)

    Fardad, M A; Luo, H; Beregovski, Y; Fallahi, M

    1999-04-01

    Solgel grating waveguides and their application to the fabrication of external-cavity distributed Bragg reflector (DBR) lasers are demonstrated. A new composition of aluminosilicate material is developed for the fabrication of single-mode waveguides and Bragg reflectors. An average loss of <0.2 dB/cm is measured in the single-mode waveguides at 1550 nm. The reflectors show filtering greater than 97% near 1530 nm, with a bandwidth of ~0.6 nm . The Bragg reflectors are used as feedback resonators for DBR lasers. Single-mode lasing with a sidemode suppression of better than 25 dB is demonstrated. PMID:18071539

  14. Efficient interpretation algorithm for embedded Bragg gratings for damage detection in composites

    Science.gov (United States)

    Prabhugoud, Mohanraj; Peters, Kara J.

    2003-07-01

    The goal of a structural health monitoring system is to detect, locate, and identify damages in a structure during its lifetime. The concept of structural health monitoring is particularly important for fiber reinforced composites due to the complexity of the possible failure mechanisms. The goal of this work is to simulate the response of optical fiber Bragg grating sensors to multi-component loading for their implementation in structural health monitoring algorithms for composites. A simulation method is presented to determine the effects of axial, bending and shear loading on an embedded optical fiber Bragg grating sensor. The effect of fiber bending on the Bragg grating sensor is experimentally verified by embedding the sensor in a solid cone, clamped at the base and subjected to a point load at the apex. Next, a numerically efficient method to calculate the response of sensors embedded in a unidirectional composite is developed using both finite element analysis and optimal shear-lag theory and taking into account the above effects. The limitations of the optimal shear-lag theory are derived through comparison with the finite element results. The application of this method is demonstrated through a numerical example, simulating the response of sensors embedded in one fiber layer to a transverse crack.

  15. Moiré Fibre Bragg Grating Written on Strained Fibres

    Institute of Scientific and Technical Information of China (English)

    孙磊; 冯新焕; 刘艳格; 张伟刚; 袁树忠; 开桂云; 董孝义

    2004-01-01

    Moiré fibre Bragg gratings are made in a single mode fibre and a polarization-maintaining fibre respectively, using an excimer KrF laser and a phase mask. Two gratings are written at the same location of the optical fibre. The wavelength spacing can be finely tuned from 0 to 1.86nm by straining the optical fibre during UV illumination.

  16. D-shaped fiber grating refractive index sensor induced by an ultrashort pulse laser.

    Science.gov (United States)

    Liao, Changrui; Wang, Qiao; Xu, Lei; Liu, Shen; He, Jun; Zhao, Jing; Li, Zhengyong; Wang, Yiping

    2016-03-01

    The fabrication of fiber Bragg gratings was here demonstrated using ultrashort pulse laser point-by-point inscription. This is a very convenient means of creating fiber Bragg gratings with different grating periods and works by changing the translation speed of the fiber. The laser energy was first optimized in order to improve the spectral properties of the fiber gratings. Then, fiber Bragg gratings were formed into D-shaped fibers for use as refractive index sensors. A nonlinear relationship was observed between the Bragg wavelength and liquid refractive index, and a sensitivity of ∼30  nm/RIU was observed at 1.450. This shows that D-shaped fiber Bragg gratings might be used to develop promising biochemical sensors. PMID:26974608

  17. The Wavelength Shifting and Temperature Athermalization of Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    Yu; e; Kong

    2003-01-01

    The wavelength shifting properties and the temperature athermalization technology of fiber Bragg grating (FBG) were studied in this paper, and then two different athermalization methods were introduced. The research shows that FBG with athermalization by applying the substrate with negative coefficient of thermal expansion is effective and can be used in many fields.

  18. High Sensitivity Polymer Optical Fiber-Bragg-Grating-Based Accelerometer

    DEFF Research Database (Denmark)

    Stefani, Alessio; Andresen, Søren; Yuan, Wu;

    2012-01-01

    We report on the fabrication and characterization of the first accelerometer based on a polymer optical fiber Bragg grating (FBG) for operation at both 850 and 1550 nm. The devices have a flat frequency response over a 1-kHz bandwidth and a resonance frequency of about 3 kHz. The response is line...

  19. UV writing of advanced Bragg gratings in optical waveguides

    DEFF Research Database (Denmark)

    Jensen, Jesper Bo Damm

    2002-01-01

    were then translated into a polarizer angle profile and the Bragg grating were written using a pulsed excimer laser. Only optical fibers were used in this part of the thesis. The high quality planar waveguides used during the study were produced in the cleanroom facility at the Microelectronic Center...

  20. Optimization of Apodized Chirped Fiber Bragg Grating for Dispersion Compensation

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Multiwavelength chirped fiber Bragg grating (MCFBG) is a more valuable approach to chromatic dispersion compensation. And adjusting the structure of FBG will optimize the performance of dispersion compensator in 8×10Gb/s DWDM network, which is proved by simulating calculation.

  1. Rational solitons in deep nonlinear optical Bragg grating

    NARCIS (Netherlands)

    Alatas, H.; Iskandar, A.A.; Tjia, M.O.; Valkering, T.P.

    2006-01-01

    We have examined the rational solitons in the Generalized Coupled Mode model for a deep nonlinear Bragg grating. These solitons are the degenerate forms of the ordinary solitons and appear at the transition lines in the parameter plane. A simple formulation is presented for the investigation of the

  2. Perimeter security alarm system based on fiber Bragg grating

    Science.gov (United States)

    Zhang, Cui; Wang, Lixin

    2010-11-01

    With the development of the society and economy and the improvement of living standards, people need more and more pressing security. Perimeter security alarm system is widely regarded as the first line of defense. A highly sensitive Fiber Bragg grating (FBG) vibration sensor based on the theory of the string vibration, combined with neural network adaptive dynamic programming algorithm for the perimeter security alarm system make the detection intelligently. Intelligent information processing unit identify the true cause of the vibration of the invasion or the natural environment by analyzing the frequency of vibration signals, energy, amplitude and duration. Compared with traditional perimeter security alarm systems, such as infrared perimeter security system and electric fence system, FBG perimeter security alarm system takes outdoor passive structures, free of electromagnetic interference, transmission distance through optical fiber can be as long as 20 km It is able to detect the location of event within short period of time (high-speed response, less than 3 second).This system can locate the fiber cable's breaking sites and alarm automatically if the cable were be cut. And the system can prevent effectively the false alarm from small animals, birds, strong wind, scattering things, snowfalls and vibration of sensor line itself. It can also be integrated into other security systems. This system can be widely used in variety fields such as military bases, nuclear sites, airports, warehouses, prisons, residence community etc. It will be a new force of perimeter security technology.

  3. Flexible nanofiber-coupled hybrid plasmonic Bragg grating.

    Science.gov (United States)

    Liu, Sheng; Zhou, Linjie; Xu, Jian; Wang, Xinyi; Chen, Jianping

    2016-05-01

    We report a hybrid plasmonic Bragg grating composed of a nanofiber coupled with orthogonally oriented metal strips. Numerical simulations are performed to study the transmission and reflection spectra of the grating. It shows that the TM polarization has much stronger Bragg reflection due to the excitation of hybrid plasmonic modes. The dependence of reflection peaks on several key device parameters is analyzed. Light propagation simulation further reveals that both fundamental and first-order TM modes are excited upon Bragg reflection, leading to two separate peaks in the spectrum. We implement the prototype device by attaching a nanofiber onto the surface of an array of sub-micrometer-wide metal strips. The main reflection peak is measured to have a 3-dB bandwidth of 15 nm and out-of-band rejection of more than 30 dB. The effects of nanofiber radius, alignment angle and coupling length on the device performance are also experimentally investigated. PMID:27137547

  4. Silicon waveguide polarization rotation Bragg grating with phase shift section and sampled grating scheme

    Science.gov (United States)

    Okayama, Hideaki; Onawa, Yosuke; Shimura, Daisuke; Yaegashi, Hiroki; Sasaki, Hironori

    2016-08-01

    We describe a Bragg grating with a phase shift section and a sampled grating scheme that converts input polarization to orthogonal polarization. A very narrow polarization-independent wavelength peak can be generated by phase shift structures and polarization-independent multiple diffraction peaks by sampled gratings. The characteristics of the device were examined by transfer matrix and finite-difference time-domain methods.

  5. Low-Dispersion Fibre Bragg Gratings Written Using the Polarization Control Method

    DEFF Research Database (Denmark)

    Deyerl, Hans Jürgen; Plougmann, Nikolai; Jensen, Jesper Bo Damm;

    2002-01-01

    We present two fibre Bragg gratings with reduced in-band dispersion for DWDM applications. The gratings were designed by the inverse scattering method and fabricated using the novel polarization control method for UV-writing of advanced gratings.......We present two fibre Bragg gratings with reduced in-band dispersion for DWDM applications. The gratings were designed by the inverse scattering method and fabricated using the novel polarization control method for UV-writing of advanced gratings....

  6. Fiber Bragg Gratings, IT Techniques and Strain Gauge Validation for Strain Calculation on Aged Metal Specimens

    OpenAIRE

    Ander Montero; Idurre Saez de Ocariz; Ion Lopez; Pablo Venegas; Javier Gomez; Joseba Zubia

    2011-01-01

    This paper studies the feasibility of calculating strains in aged F114 steel specimens with Fiber Bragg Grating (FBG) sensors and infrared thermography (IT) techniques. Two specimens have been conditioned under extreme temperature and relative humidity conditions making comparative tests of stress before and after aging using different adhesives. Moreover, a comparison has been made with IT tecniques and conventional methods for calculating stresses in F114 steel. Implementation of Structural...

  7. Field Deployable Fiber Bragg Grating Strain Patch for Long-Term Stable Health Monitoring Applications

    OpenAIRE

    Gerhard Kalinka; Wolfgang Habel; Nadine Kusche; Vivien Schukar

    2013-01-01

    A fiber Bragg grating (FBG) strain patch specially adapted for long-term and high-strain applications has been developed and characterized. The design concept for the patch is based on a glass-fiber reinforced plastic (gfrp) carrier material. The developed concept for the FBG integration into the carrier material was derived from reliable integration procedure of FBG sensors into composite structures. The patches’ temperature sensitivity, strain gauge factor, fiber–matrix ...

  8. Optical Fiber Grating based Sensors

    DEFF Research Database (Denmark)

    Michelsen, Susanne

    2003-01-01

    sampled gratings, was produced and investigated. It is based on the different temperature and strain response of these gratings. Both a transfer matrix method and an overlap calculation is performed to explain the sensor response. Another type of sensor is based on tuning and modulation of a laser...

  9. Active temperature compensation design of sensor with fiber gratings

    Institute of Scientific and Technical Information of China (English)

    Xingfa Dong(董兴法); Yonglin Huang(黄勇林); Li Jiang(姜莉); Guiyun Kai(开桂云); Xiaoyi Dong(董孝义)

    2004-01-01

    A technique for compensation of temperature effects in fiber grating sensors is reported. For strain sensors and other sensors related to strain such as electromagnetic sensors, a novel structure is designed, which uses two fiber Bragg gratings (FBGs) as strain differential sensor and has temperature effects cancelled. Using this technique, the stress sensitivity has been amplified and gets up to 0.226 nm/N, the total variation in wavelength difference within the range of 3-45 ℃ is 0.03 nm, 1/14 of the uncompensated FBG.The structure can be used in the temperature-insensitive static strain measurement and minor-vibration measurement.

  10. A novel optical filter of fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    LI; Xiaolu; JIANG; Yuesong

    2006-01-01

    A theory of a novel optical filter of drawing the fiber Bragg grating by the heated elastic sheet is advanced. Based on the heat conduction equation, a set of functions of temperature and thermal expansion on the heated elastic sheet are calculated. And the most displacement of the heated elastic sheet is also described. Finally the expression of the reflected Bragg wavelength deviation in terms of the thermal power density of heat-source is deduced. The physics feasibility of these conclusions mentioned above is proved. It is a potential value for the novel optical filter to research.

  11. Blood pressure manometer using a twin Bragg grating Fabry-Perot interferometer

    Science.gov (United States)

    van Brakel, Adriaan; Swart, Pieter L.; Chtcherbakov, Anatoli A.; Shlyagin, Mikhail G.

    2005-02-01

    We propose the use of optical fiber Bragg gratings in a non-invasive blood pressure waveform monitor. Bragg gratings can be written in a Fabry-Perot interferometric configuration to yield a method of strain measurement that has both a high resolution and a wide unambiguous range. This fiber Bragg grating Fabry-Perot interferometer (FBGI) can be used as a sensor to detect strain resulting from blood pressure applied to the walls of an artery situated near the patient"s skin. Strain measurements taken on the skin surface, typically over the radial artery at the wrist, are encoded as phase shifts of the FBGI signal. These phase shifts may be obtained by the analytic representation of the interferometer signal in the wavelength domain or by Fourier analysis in the frequency domain. For the proof of concept a realistic physical model was constructed to simulate pressure conditions at the actual sensor location. The operation of the device is demonstrated by measurements of pressure-pulse waveforms obtained in real-time. This sensor was also successfully tested on human patients, and these results are also presented. Since it yields continuous readings of blood pressure non-invasively, further application of the optical manometer may yield an alternative to conventional sphygmomanometry.

  12. Research on pressure tactile sensing technology based on fiber Bragg grating array

    Science.gov (United States)

    Song, Jinxue; Jiang, Qi; Huang, Yuanyang; Li, Yibin; Jia, Yuxi; Rong, Xuewen; Song, Rui; Liu, Hongbin

    2015-09-01

    A pressure tactile sensor based on the fiber Bragg grating (FBG) array is introduced in this paper, and the numerical simulation of its elastic body was implemented by finite element software (ANSYS). On the basis of simulation, fiber Bragg grating strings were implanted in flexible silicone to realize the sensor fabrication process, and a testing system was built. A series of calibration tests were done via the high precision universal press machine. The tactile sensor array perceived external pressure, which is demodulated by the fiber grating demodulation instrument, and three-dimension pictures were programmed to display visually the position and size. At the same time, a dynamic contact experiment of the sensor was conducted for simulating robot encountering other objects in the unknown environment. The experimental results show that the sensor has good linearity, repeatability, and has the good effect of dynamic response, and its pressure sensitivity was 0.03 nm/N. In addition, the sensor also has advantages of anti-electromagnetic interference, good flexibility, simple structure, low cost and so on, which is expected to be used in the wearable artificial skin in the future.

  13. Acoustic Emission Measurement with Fiber Bragg Gratings for Structure Health Monitoring

    Science.gov (United States)

    Banks, Curtis E.; Walker, James L.; Russell, Sam; Roth, Don; Mabry, Nehemiah; Wilson, Melissa

    2010-01-01

    Structural Health monitoring (SHM) is a way of detecting and assessing damage to large scale structures. Sensors used in SHM for aerospace structures provide real time data on new and propagating damage. One type of sensor that is typically used is an acoustic emission (AE) sensor that detects the acoustic emissions given off from a material cracking or breaking. The use of fiber Bragg grating (FBG) sensors to provide acoustic emission data for damage detection is studied. In this research, FBG sensors are used to detect acoustic emissions of a material during a tensile test. FBG sensors were placed as a strain sensor (oriented parallel to applied force) and as an AE sensor (oriented perpendicular to applied force). A traditional AE transducer was used to collect AE data to compare with the FBG data. Preliminary results show that AE with FBGs can be a viable alternative to traditional AE sensors.

  14. Note: Strain sensitivity comparison between fiber Bragg gratings inscribed on 125 and 80 micron cladding diameter fibers, case study on the solidification monitoring of a photo-curable resin

    Energy Technology Data Exchange (ETDEWEB)

    Maccioni, E. [Dipartimento di Fisica, Università degli Studi di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Istituto Nazionale di Fisica Nucleare (INFN) sez. di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Morganti, M. [Istituto Nazionale di Fisica Nucleare (INFN) sez. di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Accademia Militare di Livorno, Viale Italia 72, 57100 Livorno (Italy); Brandi, F., E-mail: fernando.brandi@ino.it [Nanophysics Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Istituto Nazionale di Ottica (INO), Consiglio Nazionale delle Ricerche (CNR), Via G. Moruzzi 1, 56124 Pisa (Italy)

    2015-02-15

    The influence of fiber Bragg grating diameter when measuring strain is investigated and quantified. Two fiber Bragg gratings with bare cladding diameter of 125 μm and 80 μm are produced by excimer laser irradiation through a phase mask, and are used to simultaneously monitor the Bragg wavelength shift due to the strain produced by the solidification of a photo-curable resin during light exposure. It is found that the ratio of the measured strains in the two fiber Bragg gratings is close to the inverse ratio of the fiber’s cladding diameter. These results represent a direct simultaneous comparison between 125 μm and 80 μm diameter fiber Bragg grating strain sensors, and demonstrate the feasibility of strain measurements in photo-curable resins using bare 80 μm cladding diameter fiber Bragg gratings with an increased sensitivity and spatial resolution compared with standard 125 μm diameter fiber Bragg gratings.

  15. Photonic crystal distributed feedback fiber lasers with Bragg gratings

    DEFF Research Database (Denmark)

    Søndergaard, Thomas

    2000-01-01

    Two new types of optical fibers, where air-holes are running down their length, are considered for making fiber lasers with Bragg gratings. The mode areas for pump and signal in these fiber lasers may be either larger or smaller compared to the corresponding mode areas for fiber lasers based on...... standard step index fibers. This makes possible realization of fiber lasers with a low pump threshold (small mode area), and fiber lasers suitable for high-power applications (large mode area)...

  16. Dynamic analysis and temperature measurements of concrete cantilever beam using fibre Bragg gratings

    Science.gov (United States)

    da Silva, Jean Carlos Cardozo; Martelli, Cicero; Kalinowski, Hypolito José; Penner, Elisabeth; Canning, John; Groothoff, Nathaniel

    2007-01-01

    We analyzed the action of fire, causing degradation in a concrete cantilever beam using dynamic testing. The structure was fitted with two fibre Bragg gratings (FBG) sensors. One of them measured vibration and the other measured the temperature inside of the cantilever beam, while the beam was exposed to fire. A high-temperature probe based on a simple packaging system, which isolates the sensing FBG from any mechanical action, was developed. A low-cost fibre Bragg grating interrogation system, including easy assembly and maintenance, was used for the measurements. The temperature in the cantilever beam increased until 150 °C and a reduction in the strength of concrete was observed through modal analysis. Results reveal a considerable reduction in strength occurs even with exposures to moderate temperatures (less than 90 °C).

  17. Covalent Attachment of Carbohydrate Derivatives to an Evanescent Wave Fiber Bragg Grating Biosensor

    Directory of Open Access Journals (Sweden)

    Christopher J. Stanford

    2009-01-01

    Full Text Available A carbohydrate-based biosensor was prepared by functionalization of the surface of an etched fiber Bragg grating with a glucopyranosyl-siloxane conjugate. Functionalization of the surface with the conjugate resulted in a Bragg grating shift of 24 pm. This shift in the refractive index is consistent with a theoretical shift calculated assuming monolayer coverage of the glucose conjugate on the sensor. The resulting functionalized fiber was shown to interact selectively with concanavalin A (Con A, a glucose binding protein (lectin. Exposure of the glucose-functionalized fiber to peanut agglutinin, a galactosebinding lectin, did not result in a change of the refractive index corresponding to a binding event.

  18. Sensitivity of Bragg gratings in birefringent optical fiber to transverse compression between conforming materials.

    Science.gov (United States)

    Dennison, Christopher R; Wild, Peter M

    2010-04-20

    A theoretical and experimental investigation of the transverse load sensitivity of Bragg gratings in birefringent fibers to conforming contact is presented. A plane elasticity model is used to predict the contact dimensions between a conforming material and optical fiber and the principal stresses, indicating birefringence, created as a result of this contact. The transverse load sensitivity of commercially available birefringent fiber is experimentally measured for two cases of conforming contact. Theoretical and experimental results show that birefringent optical fiber can be used to make modulus-independent measurements of contact load. Therefore, Bragg gratings could be applied to conforming contact load measurements while avoiding some of the complications associated with existing contact sensors: specifically, the necessity to precalibrate by using materials with mechanical properties identical to those found in situ.

  19. Spectral interference fringes in chirped large-mode-area fiber Bragg gratings

    Science.gov (United States)

    Poozesh, Reza; Madanipour, Khosro; Vatani, Vahid

    2016-09-01

    Spectral interference fringes were experimentally observed in chirped large mode area fiber Bragg grating (CFBG) in the overlapping region of the reflected spectrum of fiber modes by a high resolution spectrometer. It was demonstrated that the interference is due to optical path difference of the reflected modes in slight chirped FBGs. By assuming chirped fiber Bragg gratings as a Fabry-Perot (FP) cavity, free spectral range (FSR) of FP was calculated 0.08 nm which is matched with measurement very well. Furthermore, the experiments show that axial tension and temperature changes of the CFBG do not have observable effects on the magnitude of FSR, however coiling of the fiber deceases spectral interference fringe amplitude without sensible effect on FSR magnitude. The results of this work can be utilized in bending sensors.

  20. Study on rock deformation monitoring using fiber Bragg grating in simulation experiment

    Institute of Scientific and Technical Information of China (English)

    CHAI Jing; WEI Shi-ming; LIU Jin-xuan

    2006-01-01

    Presented the fiber Bragg grating (FBG) sensors for rock strain monitoring in the 1.2 m long plane stress model of the simulation experiment. In the past, for the lack of appropriate technique to measure the deformation of rock structures, the measurement of deflection was restricted to just a few discrete points along rock, and the measuring points were limited to the location-installed with displacement transducers. We developed a method to monitor the deformation of rock structures using fiber optical Bragg grating strain sensors. The sensors were embedded in rock layers of simulation experiment before the materials were put in. These sensors were then used to monitor the experienced strain with different face advancing distance. The test results indicate that, if properly installed FBG sensors can survive under severe conditions associated with embedment process and yield accurate measurements of strains response. At the same time, we make comparisons of the data obtained by FBG sensors with those by centesimal gauge.The interest in FBG sensors was motivated by the potential advantages that they can offer more than existing sensing technologies.

  1. Influence of Non-uniform Temperature Field on Spectra of Fibre Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yan; HE Xing-Fang; YUAN Jie; YIN Li-Qun; FANG Xiao-Yong; CAO Mao-Sheng

    2009-01-01

    We simulate the spectrum characteristics of fibre Bragg grating (FBG) with non-uniform temperature using the transmission matrix method, and the results are analysed. It is found that firstly the modulated coefficient of average refractive index is a very important parameter that influences the spectrum characteristic of the fibre Bragg grating, and secondly the spectrum curves are different in different temperature fields at the same parameter. Hence, we can determine the metrical temperature by analysing the spectrum of fibre Bragg grating.

  2. Fabrication of High Quality Broadband Type IIA Chirped Fiber Bragg Gratings

    Institute of Scientific and Technical Information of China (English)

    SANG Xin-zhu; YU Chong-xiu; YAN Bin-bin; MA Jian-xin; LU Nai-guang

    2006-01-01

    Chirped fiber Bragg gratings have found many applications in optical communication and sensing systems. High quality filters based on chirped fiber Bragg gratings with reflection bandwidth of 2.6 and 32nm and high reflectivity are demonstrated experimentally with 2 and 4cm long phase masks, respectively. These filters with flat reflection band and high reflectivity are achieved by writing type IIA chirped Bragg gratings.

  3. Spectral characteristics of draw-tower step-chirped fiber Bragg gratings

    Science.gov (United States)

    Idrisov, Ravil F.; Varzhel, Sergey V.; Kulikov, Andrey V.; Meshkovskiy, Igor K.; Rothhardt, Manfred; Becker, Martin; Schuster, Kay; Bartelt, Hartmut

    2016-06-01

    This paper presents research results on the spectral properties of step-chirped fiber Bragg grating arrays written during the fiber drawing process into a birefringent optical fiber with an elliptical stress cladding. The dependences of resonance shift of the step-chirped fiber Bragg grating on bending, on applied tensile stress and on temperature have been investigated. A usage of such step-chirped fiber Bragg gratings in fiber-optic sensing elements creation has been considered.

  4. Single- and Two-Phase Flow Characterization Using Optical Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Virgínia H.V. Baroncini

    2015-03-01

    Full Text Available Single- and two-phase flow characterization using optical fiber Bragg gratings (FBGs is presented. The sensor unit consists of the optical fiber Bragg grating positioned transversely to the flow and fixed in the pipe walls. The hydrodynamic pressure applied by the liquid or air/liquid flow to the optical fiber induces deformation that can be detected by the FBG. Given that the applied pressure is directly related to the mass flow, it is possible to establish a relationship using the grating resonance wavelength shift to determine the mass flow when the flow velocity is well known. For two phase flows of air and liquid, there is a significant change in the force applied to the fiber that accounts for the very distinct densities of these substances. As a consequence, the optical fiber deformation and the correspondent grating wavelength shift as a function of the flow will be very different for an air bubble or a liquid slug, allowing their detection as they flow through the pipe. A quasi-distributed sensing tool with 18 sensors evenly spread along the pipe is developed and characterized, making possible the characterization of the flow, as well as the tracking of the bubbles over a large section of the test bed. Results show good agreement with standard measurement methods and open up plenty of opportunities to both laboratory measurement tools and field applications.

  5. Real-time calibrating demodulation system of fiber Bragg grating sensor%一种实时校准的光纤Bragg光栅传感器解调系统

    Institute of Scientific and Technical Information of China (English)

    陈亮; 黄俊斌; 顾宏灿; 谭波

    2009-01-01

    To improve the demodulation precision of fiber Bragg grating ( FBG) sensor array, a real-time calibrating demodulation system which is based on narrow band light source inquiring demodulation method and using impervious to temperature regulator with marker,is presented. The signal is gathered into computer by 12 bit A/D and processed by LabVIEW. The peak detection method is searching peak in subsections. Experiments show that the Bragg wavelength demodulation precision of FBG sensor reaches 1pm and is ten multiple higher than precision of system without real-time calibrating module. Then strain measured experiment shows the error is lower than 1.5×10~(-6) in 1×10~(-4) range.%为了提高光纤Bragg光栅(FBG)传感器阵列的信号解调精度,基于窄带光源问讯解调原理,提出了引入带标记热稳定标准具模块来实现实时校准的方案,利用12位A/D采集模块将信号采入计算机,在虚拟仪器软件LabVIEW下处理信号,峰值检测方法为分段寻峰.实验表明:该方案对FBG传感器中心波长位移的最大解调精度为1 pm,相对于无实时校准模块方案下的解调精度提高了10倍以上,在应变为1×10~(-4)的范围内,测量误差小于1.5×10~(-6).

  6. Optofluidic Temperature and Pressure Measurements with Fiber Bragg Gratings Embedded in Microfluidic Devices

    CERN Document Server

    Cooksey, Gregory A

    2016-01-01

    The integration of photonic sensors into microfluidic devices provides opportunities for dynamic measurement of chemical and physical properties of fluids in very small volumes. We previously reported on the use of commercially available Fiber Bragg Gratings (FBGs) and on-chip silicon waveguides for temperature sensing. In this report, we demonstrate the integration of FBGs into easy-to-fabricate microfluidic devices and report on their sensitivity for temperature and pressure measurement in microliter volumes. These sensors present new routes to measurement in microfluidic applications such as small-volume calorimetry and microflow metrology.

  7. Computer-Generated Holograms for Recording Multiple-Phase-Shifte Fiber Bragg Grating Corrugations

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new method of fabricating multiple-phase-shifte fiber Bragg grating by CGHs is proposed. The authors present an example of such CGH by which a section multiple-phase-shifte fiber Bragg grating with two π/2 phase shifts and grating length L=21.2 μm was produced. The authors describe the production process and finally give an example of a reconstructed fiber grating with two phase-shifts.

  8. Fiber Grating Sensor with Enhanced Pressure and Temperature Sensitivity

    Institute of Scientific and Technical Information of China (English)

    LIU Yun-Qi; GUO Zhuan-Yun; LIU Zhi-Guo; ZHAO Dong-Hui; GE Chun-Feng; DONG Xiao-Yi

    2000-01-01

    A technique is used to enhance the pressure and temperature sensitivity of a fiber Bragg grating sensor. The grating is packaged by using polymer jacket, which exhibits no significant chirp due to the adoption of the special technique. The measured pressure and temperature sensitivity of the structured grating is 6.28×10-5 / MPa and5.18×10-5/℃. The wavelength shift due to pressure and temperature can be enhanced about 31.5 times for pressure and 7.7 times for temperature.

  9. Bragg grating inscription in CYTOP polymer optical fibre using a femtosecond laser

    Science.gov (United States)

    Lacraz, A.; Polis, M.; Theodosiou, A.; Koutsides, C.; Kalli, K.

    2015-05-01

    We report on the inscription of fibre Bragg gratings (FBGs) in CYTOP (cyclic transparent optical polymer) optical fibres. A femtosecond laser beam, operating in the visible wavelength range, is focussed into the core of the fibre for direct inscription of FBGs. The fibre is moved under the focussed beam by a nanometre-resolution air-bearing stage for maximal inscription precision. The grating plane dimensions (measured with bright field microscopy) are typically 30μm × 30μm × 1μm (line by line grating) or 10μm×1μm×1μm (point by point grating) and centred in the core of the fibre for optimal grating efficiency. The FBGs have a typical reflectivity of 70%, a bandwidth of 0.25nm and an index change of ~10-4. The FBG operate in the C-band, where CYTOP offers key advantages over poly (methyl methacrylate) optical fibres, having a significantly lower optical loss in the important near infra-red (NIR) optical communications window, with a theoretical loss of ~0.3dB/km at 1550nm. Additionally, CYTOP has a far lower affinity for water absorption and a core mode refractive index that coincides with the aqueous index regime. These properties offer several unique opportunities for polymer optical fibre sensing at NIR wavelengths, such as compatibility with existing optical networks, the potential for optical fibre sensor multiplexing and suitability for bio-sensing. We have investigated the temperature response of the grating: a linear positive shift of ~ +40pm/K has been measured with little difference between the heating and cooling response. The strain response of the FBG has also been studied with a linear shift of ~ +1.3pm/μɛ measured over a few hundreds of μɛ. We also demonstrated compatibility with a commercial Bragg grating demodulator.

  10. Study on the fiber grating sensors in concrete safety monitoring

    Science.gov (United States)

    Liu, Hang; Li, Yang; Zhang, Yu-hong

    2014-09-01

    The concrete may be damaged because there are freeze-thaw cycles between winter and summer in cold regions. Strain is an alternative parameter which can be used to describe deformation. In this paper, the fiber bragg gratings(FBG) were used to concrete safety monitoring. The strain and temperature sensing properties have been studied. The fiber reinforced polymers (FRP) were used for the packaged techniques of FBG sensors. The neural network was applied to temperature compensation for FBG sensors.

  11. OPTIMIZATION OF INTRAGRATING SENSING USING FIBER BRAGG GRATING

    OpenAIRE

    B.B.PADHY; HAFTAY ABADI GEBRU; SANDIPAN M.NALAWADE

    2011-01-01

    Linearly Chirped Fiber Bragg Gratings (FBGs) have been optimized and investigated for intragrating sensing. The side lobes have been suppressed using Gaussian apodization while maintaining the peak reflectivity and the bandwidth of the reflected signal. We have achieved a chirp rate of 0.5 to 2 nm/mm for intragrating sensing.Average thermal sensitivity of 11.55 pm/ oC is obtained which is higher than uniform FBGs. We have achieved novel characteristics of linearly chirped FBGs under the effec...

  12. OPTIMIZATION OF INTRAGRATING SENSING USING FIBER BRAGG GRATING

    Directory of Open Access Journals (Sweden)

    B.B.PADHY

    2011-01-01

    Full Text Available Linearly Chirped Fiber Bragg Gratings (FBGs have been optimized and investigated for intragrating sensing. The side lobes have been suppressed using Gaussian apodization while maintaining the peak reflectivity and the bandwidth of the reflected signal. We have achieved a chirp rate of 0.5 to 2 nm/mm for intragrating sensing.Average thermal sensitivity of 11.55 pm/ oC is obtained which is higher than uniform FBGs. We have achieved novel characteristics of linearly chirped FBGs under the effect of non-monotonic physical parameter distribution fields for excellent spectral response profile for intragrating sensing.

  13. Fiber design and realization of point-by-point written fiber Bragg gratings in polymer optical fibers

    DEFF Research Database (Denmark)

    Stefani, Alessio; Stecher, Matthias; Town, Graham E.;

    2012-01-01

    An increasing interest in making sensors based on fiber Bragg gratings (FBGs) written in polymer optical fibers (POFs) has been seen recently. Mostly microstructured POFs (mPOFs) have been chosen for this purpose because they are easier to fabricate compared, for example, to step index fibers...... and the very long times required for the writing of FBGs raise some questions about the possibility of exporting POF FBGs and the sensors based on them from the laboratory bench to the mass production market. The possibility of arbitrary design of fiber Bragg gratings and the very short time required to write....... The grating was inspected under Differential Interferometric Contrast microscope and the reflection spectrum was measured. This is, to the best of our knowledge, the first FBGs written into a mPOF with the point-by-point technique and also the fastest ever written into a polymer optical fiber, with less than...

  14. Simultaneous demodulation of polarization mode coupling and fiber Bragg grating within a polarization maintaining fiber

    Science.gov (United States)

    Zhao, Yanshuang; Liu, Yanlei; Zhang, Jianzhong; Yang, Jun; Canning, John; Peng, G. D.; Chen, Yujin; Yuan, Libo

    2015-09-01

    We propose a simultaneous demodulation scheme of polarization mode coupling and fiber Bragg grating in a polarization maintaining fiber based on a white light interferometer. A polarization maintaining fiber with two inscribed fiber Bragg gratings is used to demonstrate the feasibility.

  15. Application of Multiscale Fiber Optical Sensing Network Based on Brillouin and Fiber Bragg Grating Sensing Techniques on Concrete Structures

    OpenAIRE

    Xuefeng Zhao; Jie Lu; Ruicong Han; Xianglong Kong; Yanhong Wang; Le Li

    2012-01-01

    The paper reports the application of the distributed optical fiber sensing technology and the FBG sensing technology in bridge strain monitoring; the overall changeable characteristics of the whole structure can be obtained through the distributed optical fiber sensing technology (BOTDA), meanwhile the accurate information of local important parts of the structure can be obtained through the optical fiber Bragg grating sensor (FBG), which can improve the accuracy of the monitoring. FBG sensor...

  16. Experimental and theoretical analysis of fiber Bragg gratings under Transverse Force to a Small Grating Section

    Institute of Scientific and Technical Information of China (English)

    WU Fei; LI Li-xin; LI Ya-pin; LI Zhi-quan

    2005-01-01

    Fiber Bragg grating under transverse force on a small grating section is studied by numerical simulation and experimentation. A numerical simulation based on the transfer matrix method is used to calculate the consequent changes in reflected spectrum. The reflected spectra of the FBG subjected to the transverse force split into two main peaks, and the split point shifted linearly and periodically versus the applied force. The split point is shifted in the bandwidth with the period of 11N, and the sensitivity of the split point wavelength shift versus the applied force is 0.05 nm/N in one period. The experimental results show good agreement with the simulation analysis.

  17. Grating solitons near the photonic bandgap of a fiber Bragg grating

    Energy Technology Data Exchange (ETDEWEB)

    Senthilnathan, K. [Photonics Research Center and Department of Electronic and Information Engineering, Hong Kong Polytechnic University, Hong Kong (China); Ramesh Babu, P. [Department of Physics, Vellore Institute of Technology, Deemed University, Vellore 632014 (India); Porsezian, K. [Department of Physics, Pondicherry University, Pondicherry 605014 (India)]. E-mail: porsz@hotmail.com; Santhanam, V. [Department of Physics, Presidency College, University of Madras, Chennai 600005 (India); Gnanasekaran, S. [Department of Physics, Anna University, Chennai 600025 (India)

    2007-07-15

    In this paper, we consider the nonlinear pulse propagation through a fiber Bragg grating (FBG) structure wherein the nonlinearity includes both cubic and quintic effects. We study theoretically the formation of bright grating solitons in such a FBG when the carrier frequency of a nonlinear laser pulse is detuned out of the proper edge of the photonic bandgap (PBG). By using multiple scale analysis, we investigate the generation of the bright soliton near the PBG with the higher order linear and nonlinear effects. We also study the impact of quintic nonlinearity on the dispersion curves by deriving the nonlinear dispersion relation from the governing equations.

  18. Development of sensors based on the fiber Bragg grating technology to measure strain changes at volcanoes (MED-SUV project; WP 2; Sub-Task 2.2.2)

    Science.gov (United States)

    Beverini, Nicolò; Calamai, Massimo; Carbone, Daniele; Francesconi, Francesco; Gambino, Salvo; Grassi, Renzo; Messina, Alfio Alex; Maccioni, Enrico; Morganti, Mauro; Sorrentino, Fiodor

    2014-05-01

    Stress and strain changes at volcanic areas are recognized among the best indicators of changes in the activity of the system, and its possible evolution towards critical stages. Depending on their time evolution, stress and strain changes have been the focus of either geodetic (static changes) or seismological (dynamical changes) studies. In volcano geodesy, encouraging results have been obtained though borehole strain-meters. However, they are not easy to install and involve high costs. Therefore, the near future of strain observations at volcanoes depends on the development of broad-band sensors which are low-cost and easy to install, even in the form of dense arrays. Advancements in opto-electronics have allowed the development of low-cost sensors, reliable, rugged and compact, which are particularly suitable for on-field application. In the framework of WP 2 (New monitoring and Observing systems) of the MED-SUV project, the sub-task 2.2 involves the development of strain sensors based on the fiber Bragg grating (FBG) technology. In comparison with previous implementation of the FBG technology to study rock deformations, the system that is being developed within MED-SUV is expected to offer a significantly higher resolution and accuracy in static measurements. Moreover, a careful study will be carried out in order to obtain a smooth dynamic response up to 100 Hz, thus allowing the observation of seismic waves. Finally, strategies to implement a tri-axial configuration will be studied. The performances of the proposed systems will be tailored to suit the requirements of volcano monitoring, with special attention to the trade-off between resolution and cost. Here we present an overview of FBG technology applied to strain measurement, the main objectives of our sub-task in the framework of MED-SUV and some preliminary data from a test installation on Etna.

  19. Fabrication of Dual-Wavelength Fiber Bragg Grating with a Longitudinal Stretch

    Institute of Scientific and Technical Information of China (English)

    JIANG Li; ZHANG Dong-sheng; ZHANG Wei-gang; KAI Gui-yun; DONG Xiao-yi

    2006-01-01

    A method of fabricating dual-wavelength fiber Bragg grating with a uniform phase mask is demonstrated.Theoretical analysis and numerical simulation using Matrix method arc given.The moving exposing technique is adopted.Good control over the grating's reflectivity and the separation of the two Bragg wavelengths is enabled by adjusting the stretch,the length of the grating,and the exposure.A grating with two equal transmission peaks of 19.5 dB is obtained by using this method,and the separation of the two Bragg wavelengths is 0.78 nm.

  20. A high sensitive fiber Bragg grating(FBG) geophone detecting system

    Science.gov (United States)

    Wang, Jin-Yu; Qi, Hai-Feng; Song, Guang-Dong; Wang, Chang; Liu, Tong-Yu

    2012-02-01

    A high sensitive fiber Bragg grating (FBG) geophone detecting system based on narrow line width distributed feedback (DFB) laser is realized by using filtering demodulation. Sensitivity of FBG geophone lies on the structure of the sensor shell and the shape of the reflectivity spectrum of FBG. Experiments on the detecting system's frequency character have been done. Results show that this geophone can detect the smallest acceleration of 1mm/s2 with a flat response from 5Hz to 40Hz.. The experiments on coal mine exhibit that the geophone can be used to measure microseismic signals. The detecting system shows great prospect in micro-seismic detection, and geological disasters detecting.

  1. Application of Fiber Bragg Grating for Determining Positions of Gas Absorption Lines

    Institute of Scientific and Technical Information of China (English)

    韩文念; 汪曣; 马凤; 刘琨; 贾大功; 刘铁根; 张红霞

    2010-01-01

    Fiber Bragg grating(FBG) is used as a wavelength reference device to calibrate the position of gas absorption peak in the intracavity absorption gas sensor(ICAGS) based on erbium-doped fiberring laser.This system can detect both the reflectance spectrum of FBGs and absorption spectrum of measured gas during a single wavelength sweeping process by linearly varying the driving voltage of optic filter.The voltages corresponding to center wavelength positions of four FBGs in the spectrum are determined through ...

  2. Hollow core MOEMS Bragg grating microphone for distributed and remote sensing

    DEFF Research Database (Denmark)

    Reck, Kasper; Østergaard, Christian; Thomsen, Erik Vilain;

    2011-01-01

    We present the design and fabrication of a completely new high sensitivity all-optical frequency modulated MOEMS microphone for distributed and remote sensing applications. Due to immunity to electromagnetic interference, no parasitic capacitances and easy wavelength division multiplexing (WDM......) combined with the low transmission loss of modern optical fibers [1], frequency modulated optical sensors are ideal for remote and distributed sensing. While several all-optical and high sensitivity MOEMS pressure sensors are found in literature, these sensors are typically based on amplitude (intensity......) modulation. Amplitude modulation is inherently sensitive to transmission loss and requires a unique transmission line for each sensor. Though fiber Bragg gratings (FBGs) are based on frequency modulation the relatively large dimensions of optical fibers and their low refractive index modulation makes them...

  3. Analysis of Sampled Fiber Bragg Grating Based on the Photonic Crystal Theory

    Institute of Scientific and Technical Information of China (English)

    ZHU Dan-dan

    2009-01-01

    One of the most basic characteristics of photonic crystal is frequency band gap.When defects are introduced into the periodic photonic crystal,a number of defect modes appear in the stop band.In this paper,we exploit transfer matrix method based on photonic crystal theory,and assume the sampled fiber Bragg grating as one-dimensional dual photonic crystal with a large size defect.Characteristics of the sampled fiber Bragg grating are analyzed.Experimental results show that the sampled fiber Bragg grating has many reflective peaks.Its reflectivity,center wavelength,reflective peak intervals and band width all change with the grating parameters,including grating length,duty ratio of the material with high dielectric constant,and index modulation depth and period.Results agree with the conventional couple mode theory which can be used when analyzing other characteristics of the sampled fiber Bragg grating or applying it into practice.

  4. 100 GHz electrically tunable planar Bragg gratings via liquid crystal overlay

    OpenAIRE

    Adikan, F.R.Mahamd; J.C.Gates; Snow, B.D.; Dyadyusha, A.; Major, H.E.; Gawith, C.B.E.; Kaczmarek, M.; P.G.R.Smith

    2007-01-01

    We demonstrate 114GHz electrically tunable liquid crystal Bragg gratings using 170Vpp voltage. The devices were made using direct UV grating writing and use evanescent coupling into an electrically tuned nematic liquid crystal. Reconfigurable integrated optical devices are essential in today's dense and complex telecommunication meshes. A commonly employed component on the silica platform fulfilling the above role is a planar Bragg grating. The ability to tune the reflection peak of these gra...

  5. Numerical Analysis of Thermal Dependence of the Spectral Response of Polymer Optical Fiber Bragg Gratings

    OpenAIRE

    Hisham K. Hisham

    2016-01-01

    The thermal dependence of the spectral response (i.e. transmission, reflection and time delay (r) responses) of uniform polymer optical fiber (POF) Bragg gratings has been investigated. In addition to the temperature dependence, the effects of grating strength (kLg) and fiber index modulation (n) have been investigated. Besides high capability of tunable wavelength due to the unique large and negative thermo-optic coefficient of POF, the spectral response for POF Bragg gratings sh...

  6. Detuning in apodized point-by-point fiber Bragg gratings: insights into the grating morphology.

    Science.gov (United States)

    Williams, Robert J; Krämer, Ria G; Nolte, Stefan; Withford, Michael J; Steel, M J

    2013-11-01

    Point-by-point (PbP) inscription of fiber Bragg gratings using femtosecond laser pulses is a versatile technique that is currently experiencing significant research interest for fiber laser and sensing applications. The recent demonstration of apodized gratings using this technique provides a new avenue of investigation into the nature of the refractive index perturbation induced by the PbP modifications, as apodized gratings are sensitive to variation in the average background index along the grating. In this work we compare experimental results for Gaussian- and sinc-apodized PbP gratings to a coupled-mode theory model, demonstrating that the refractive index perturbation induced by the PbP modifications has a negative contribution to the average background index which is small, despite the presence of strong reflective coupling. By employing Fourier analysis to a simplified model of an individual modification, we show that the presence of a densified shell around a central void can produce strong reflective coupling with near-zero change in the average background index. This result has important implications for the experimental implementation of apodized PbP gratings, which are of interest for a range of fiber laser and fiber sensing technologies. PMID:24216907

  7. Polarization-resolved sensing with tilted fiber Bragg gratings: theory and limits of detection

    CERN Document Server

    Bialiayeu, Aliaksandr; Albert, Jacques

    2015-01-01

    Polarization based sensing with tilted fiber Bragg grating (TFBG) sensors is analysed theoretically by two alternative approaches. The first method is based on tracking the grating transmission for two orthogonal states of linear polarized light that are extracted from the measured Jones matrix or Stokes vectors of the TFBG transmission spectra. The second method is based on the measurements along the system principle axes and polarization dependent loss (PDL) parameter, also calculated from measured data. It is shown that the frequent crossing of the Jones matrix eigenvalues as a function of wavelength leads to a non-physical interchange of the calculated principal axes; a method to remove this unwanted mathematical artefact and to restore the order of the system eigenvalues and the corresponding principal axes is provided. A comparison of the two approaches reveals that the PDL method provides a smaller standard deviation and therefore lower limit of detection in refractometric sensing. Furthermore, the pol...

  8. Note: Dissolved hydrogen detection in power transformer oil based on chemically etched fiber Bragg grating.

    Science.gov (United States)

    Jiang, Jun; Ma, Guo-ming; Song, Hong-tu; Zhou, Hong-yang; Li, Cheng-rong; Luo, Ying-ting; Wang, Hong-bin

    2015-10-01

    A fiber Bragg grating (FBG) sensor based on chemically etched cladding to detect dissolved hydrogen is proposed and studied in this paper. Low hydrogen concentration tests have been carried out in mixed gases and transformer oil to investigate the repeatability and sensitivity. Moreover, to estimate the influence of etched cladding thickness, a physical model of FBG-based hydrogen sensor is analyzed. Experimental results prove that thin cladding chemically etched by HF acid solution improves the response to hydrogen detection in oil effectively. At last, the sensitivity of FBG sensor chemically etched 16 μm could be as high as 0.060 pm/(μl/l), increased by more than 30% in comparison to un-etched FBG. PMID:26521000

  9. Design and experimental research on cantilever accelerometer based on fiber Bragg grating

    Science.gov (United States)

    Xiang, Longhai; Jiang, Qi; Li, Yibin; Song, Rui

    2016-06-01

    Currently, an acceleration sensor based on fiber Bragg grating (FBG) has been widely used. A cantilever FBG accelerometer is designed. The simulation of this structure was implemented by finite element software (ANSYS) to analyze its sensing performance parameters. And then the optimized structure was produced and calibration experiments were conducted. On the basis of simulation, optical fiber is embedded in the inner tank of the vibrating mass, and Bragg grating is suspended above the cantilever structure, which can effectively avoid the phenomenon of center wavelength chirp or broadening, and greatly improve the sensitivity of the sensor. The experimental results show that the FBG accelerometer exhibits a sensitivity of 75 pm/(m/s2) (100 Hz) and dynamic range of 60 dB. Its linearity error is <2.31% and repeatability error is <2.76%. And the resonant frequency is ˜125 Hz. The simulation results match the experimental results to demonstrate the good performance of FBG accelerometer, which is expected to be used in the actual project.

  10. Wavefront distortion optimized with volume Bragg gratings in photothermorefractive glass.

    Science.gov (United States)

    Gao, Fan; Zhang, Xiang; Sun, Xiaojie; Yuan, Xiao

    2016-03-15

    The wavefront characteristics in 2D angular filtering on the basis of two orthogonal transmitting volume Bragg gratings (VBGs) is presented. The experimental results show that middle-high frequency wavefront distortions are efficiently suppressed with VBGs. The peak-valley value of the beam at a wavelength of 1053 nm reduces from 2.075λ to 0.209λ, and the root mean square value reduces from 0.207λ to 0.041λ. The wavefront power spectrum density shows that the wavefront distribution of the beam in medium and high frequencies is corrected by the VBGs. Additionally, the far-field distribution and focusing properties of the beam are improved. The beam Strehl ratio increases from 0.43 to 0.96, and the encircled energy improves from 95% energy at 4.01 mrad to 95% energy at 1.26 mrad. PMID:26977639

  11. Fiber Bragg grating demodulation through innovative numerical procedures

    Science.gov (United States)

    Dinardo, Giuseppe; Vacca, Gaetano

    2016-01-01

    The aim of this article is to introduce an innovative algorithm for the calculation of the shift of the maximum reflectivity wavelength of a Fiber Bragg Grating experiencing an applied strain. An accurate and precise evaluation of the FBG spectrum displacement is crucial for determining the amount of the physical quantity inducing such perturbations. The proposed method is based on the Fast Fourier Transform based Cross Correlation function. Such method is compared to Least Squares Fitting (LSF) and the centroid algorithms, pointing out remarkable improvements in accuracy, precision, and time consumption performance. In addition, a further improvement of the proposed algorithm is introduced. It consists in an iteratively performed Cross Correlation algorithm. It has been proved that such improvement leads to estimations characterized by better accuracy and precision, thanks also to a considerable reduction of the peak-locking effect due to the FBG spectral resolution.

  12. Dynamic and static strain gauge using superimposed fiber Bragg gratings

    International Nuclear Information System (INIS)

    This paper demonstrates a simple and fast interrogation method for the dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to decrease nonequidistant space of generated a sensing pulse train in a time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A four times increase in the interrogation speed of dynamic strain, by generating a 2 kHz optical sensing pulse train from a 500 Hz scanning frequency, is demonstrated experimentally. The interrogation uncertainty and total harmonic distortion characterization of superimposed FBGs are tested and less than 4 pm standard deviation is obtained. (paper)

  13. Femtosecond soliton diode on heterojunction Bragg-grating structure

    CERN Document Server

    Deng, Zhigui; Li, Hongji; Fu, Shenhe; Liu, Yikun; Xiang, Ying; Li, Yongyao

    2016-01-01

    We numerically propose a scheme for realizing an all-optical femtosecond soliton diode based on a tailored heterojunction Bragg grating, which is designed by two spatially asymmetric chirped cholesteric liquid crystals. Our simulations demonstrate that with the consideration of optical nonlinearity, not only the femtosecond diode effect with nonreciprocal transmission ratio up to 120 can be achieved, but also the optical pulse evolving into soliton which maintains its shape during propagation through the sample is observed. Further, the influence of pulse width and the carrier wavelength to the femtosecond diode effect is also discussed in detail. Our demonstrations might suggest a new direction for experimentally realizing the femtosecond soliton diode based on the cholesteric liquid crystals.

  14. Comparison of optical fiber Bragg grating hydrogen sensors with Pd-based thin films and sol–gel WO3 coatings

    International Nuclear Information System (INIS)

    Pd-based thin films and sol–gel WO3 coatings are two kinds of hydrogen sensitive elements used in hydrogen concentration sensing and detection. Optical fiber hydrogen sensors are very promising solutions for flammable hydrogen detection, when the sensitive materials are integrated with optical fiber sensors. This paper reviews the sensing performance of optical fiber hydrogen sensors with these two sensitive materials, which are developed at the National Engineering Laboratory for Optical Fiber Sensing Technologies in Wuhan University of Technology. (paper)

  15. Structural health monitoring method for wind turbine trailing edge: Crack growth detection using Fibre Bragg Grating sensor embedded in composite materials

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    was developed, which simulates the FBG sensor output response, when embedded in a host material, during a crack growing/damage event. This Structure-Material-FBG model provides a tool to analyse the application of this monitoring technique in other locations/structures, by predicting the sensor output...

  16. 布拉格光栅对固化残余应力的监测%The Monitoring of Cure-induced Residual Stress by Fiber Bragg Grating Sensors

    Institute of Scientific and Technical Information of China (English)

    田恒; 王继辉; 冀运东; 叶春生; 胡海晓; 张红元

    2012-01-01

    由于复合材料在固化过程中产生的残余应力会严重影响材料的使用,并且会带来安全隐患,因此固化残余应力一直都备受关注.首先在研究和测试布拉格光栅温度和应力灵敏度的基础上,将两根光栅分别以平行于碳纤维方向和垂直于碳纤维方向置入铺层的正中间,以此获得复合材料不同方向的残余应力变化情况.监测结果表明,平行方向的光栅在监测固化的过程中受到树脂和纤维的共同作用,且冷却后材料在平行方向显示的残余应力仅有-8.8MPa,而在垂直方向的光栅在监测过程中主要受到树脂的固化影响,收缩应变较大,且冷却后的光栅由于树脂固化不均匀,致使光栅信号分裂为3段.%Because residual stress formed in the curing process can greatly affect the application and will bring security risks of composite material, it is being concerned sincerely all the time. The temperature sensitivity and stress sensitivity of fiber Bragg grating (FBG) were firstly investigated, and then two FBG sensors parallel and vertically to carbon fiber were embedded into same layer in order to in-situ monitor the changes of residual stress. The results show that FBG is affected by the fiber and resin, the residual stress monitored by FBG in parallel direction have only -8.8 MPa. The residual stress monitored by FBG in vertical direction is contracted by resin curing, and the signal is splited into three because of inconsistent resin curing in the grating.

  17. A Novel Optical Fiber Liquid-level Sensor Based on a Couple of Fiber Bragg Gratings%基于双光纤布喇格光栅的液位传感器

    Institute of Scientific and Technical Information of China (English)

    杨淑连; 申晋; 李田泽

    2009-01-01

    A novel optical fiber liquid-level sensor based on a couple of fiber Bragg gratings (FBGs) has been designed.The relationship between the liquid-level and the wavelength shift difference of the FBGs is derived.The pressure of the disc results in the distortion of an isosceles triangle cantilever structure.The distortion results in the wavelength shift of a couple of FBGs that are mounted at either side of the cantilever.By monitoring the wavelength shift difference of the two FBGs,the liquid-level can be obtained.The cross sensitive problem of the FBGs sensor can be solved by compensating the temperature effect.The central wavelength of two FBGs shifts to the shorter and longer wavelength respectively with the rise of the liquid-level,while the bandwidth is almost unchanged.The experimental results are in good agreement with the theoretical analysis and verify the feasibility of the proposed sensor with a measurement range from 2 to 3 000 mm.%设计了一种基于双光纤布喇格光栅的新型液位传感器,导出了双光纤布喇格光栅的波长漂移差与液位的关系.圆盘上受到的液体压力导致等腰三角形悬臂梁变形,从而导致安装在悬臂梁两边的光纤布喇格光栅的布喇格波长漂移.通过检测两个布喇格光栅的波长漂移差,得到被测液位.双光纤布喇格光栅通过补偿温度效应,解决了光纤布喇格光栅传感器的交叉敏感问题.该液位传感器的动态测量范围为2~3 000 mm.实验表明,双光纤布喇格光栅的中心波长随液位的增加分别向长波和短波方向漂移,而带宽几乎不变,实验和理论符合较好,该设计方案是切实可行的.

  18. Novel Bandwidth Sensor Based Fiber Grating

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, the basic principle and the design method of the bandwidth sensing of fiber grating are expounded, respectively. Several novel bandwidth sensor based fiber grating are analyzed and discussed.

  19. Impact of Saturable Gain/Loss on Bistability of Nonlinear Parity-Time Bragg Gratings

    CERN Document Server

    Phang, Sendy; Susanto, Hadi; Benson, Trevor M; Sewell, Phillip

    2014-01-01

    We report on the impact of realistic gain and loss models on the bistable operation of nonlinear parity-time Bragg gratings. In our model we include both dispersive and saturable gain and show that levels of gain/loss saturation can have significant impact on the bistable operation of a nonlinear PT Bragg grating based on GaAs material. The hysteresis of the nonlinear PT Bragg grating is analyzed for different levels of gain and loss and different saturation levels. We show that high saturation levels can improve the nonlinear operation by reducing the intensity at which the bistability occurs. However when the saturation intensity is low, saturation inhibits PT phenomena in a nonlinear PT Bragg grating.

  20. High-speed two-dimensional laser scanner based on Bragg gratings stored in photothermorefractive glass.

    Science.gov (United States)

    Yaqoob, Zahid; Arain, Muzammil A; Riza, Nabeel A

    2003-09-10

    A high-speed free-space wavelength-multiplexed optical scanner with high-speed wavelength selection coupled with narrowband volume Bragg gratings stored in photothermorefractive (PTR) glass is reported. The proposed scanner with no moving parts has a modular design with a wide angular scan range, accurate beam pointing, low scanner insertion loss, and two-dimensional beam scan capabilities. We present a complete analysis and design procedure for storing multiple tilted Bragg-grating structures in a single PTR glass volume (for normal incidence) in an optimal fashion. Because the scanner design is modular, many PTR glass volumes (each having multiple tilted Bragg-grating structures) can be stacked together, providing an efficient throughput with operations in both the visible and the infrared (IR) regions. A proof-of-concept experimental study is conducted with four Bragg gratings in independent PTR glass plates, and both visible and IR region scanner operations are demonstrated.

  1. High-speed two-dimensional laser scanner based on Bragg gratings stored in photothermorefractive glass.

    Science.gov (United States)

    Yaqoob, Zahid; Arain, Muzammil A; Riza, Nabeel A

    2003-09-10

    A high-speed free-space wavelength-multiplexed optical scanner with high-speed wavelength selection coupled with narrowband volume Bragg gratings stored in photothermorefractive (PTR) glass is reported. The proposed scanner with no moving parts has a modular design with a wide angular scan range, accurate beam pointing, low scanner insertion loss, and two-dimensional beam scan capabilities. We present a complete analysis and design procedure for storing multiple tilted Bragg-grating structures in a single PTR glass volume (for normal incidence) in an optimal fashion. Because the scanner design is modular, many PTR glass volumes (each having multiple tilted Bragg-grating structures) can be stacked together, providing an efficient throughput with operations in both the visible and the infrared (IR) regions. A proof-of-concept experimental study is conducted with four Bragg gratings in independent PTR glass plates, and both visible and IR region scanner operations are demonstrated. PMID:14503693

  2. Effects of the Facet Reflectivity of a Laser Diode on Fiber Bragg Grating Semiconductor Lasers

    Institute of Scientific and Technical Information of China (English)

    Honggang; Yu; Chang-Qing; Xu; Na; Li; Zhilin; Peng; Jacek; Wojcik; Peter; Mascher

    2003-01-01

    Effects of facet reflectivity of a laser diode on the performance of fiber Bragg grating semiconductor lasers are studied experimentally. Facet reflectivity of less than 10-4 is necessary to obtain stable oscillation wavelength.

  3. Rebar corrosion monitoring in concrete structure under salt water enviroment using fiber Bragg grating

    Science.gov (United States)

    Pan, Yuheng; Liu, Tiegen; Jiang, Junfeng; Liu, Kun; Wang, Shuang; He, Pan; Yan, Jinlin

    2015-08-01

    Monitoring corrosion of steel reinforcing bars is critical for the durability and safety of reinforced concrete structures. Corrosion sensors based on fiber optic have proved to exhibit meaningful benefits compared with the conventional electric ones. In recent years, Fiber Bragg Grating (FBG) has been used as a new kind of sensing element in an attempt to directly monitor the corrosion in concrete structure due to its remarkable advantages. In this paper, we present a novel kind of FBG based rebar corrosion monitoring sensor. The rebar corrosion is detected by volume expansion of the corroded rebar by transferring it to the axial strain of FBG when concrete structure is soaked in salt water. An accelerated salt water corrosion test was performed. The experiment results showed the corrosion can be monitored effectively and the corrosion rate is obtained by volume loss rate of rebar.

  4. Uniform Fiber Bragg Grating modeling and simulation used matrix transfer method

    Directory of Open Access Journals (Sweden)

    Abdallah Ikhlef

    2012-01-01

    Full Text Available This paper presents the modeling and simulation of an optical fiber Bragg grating for maximum reflectivity, minimum side lobe. Gating length represents as one of the critical parameters in contributing to a high performance fiber Bragg grating. The reflection spectra and side lobes strength were analyzed with different lengths .The side lobes have been suppressed using raised cosine apodization while maintaining the peak reflectivity. Such simulations are based on solving coupled mode equations by transfer matrix method.

  5. Uniform Fiber Bragg Grating modeling and simulation used matrix transfer method

    OpenAIRE

    Abdallah Ikhlef; Rachida Hedara; Mohamed Chikh-Bled

    2012-01-01

    This paper presents the modeling and simulation of an optical fiber Bragg grating for maximum reflectivity, minimum side lobe. Gating length represents as one of the critical parameters in contributing to a high performance fiber Bragg grating. The reflection spectra and side lobes strength were analyzed with different lengths .The side lobes have been suppressed using raised cosine apodization while maintaining the peak reflectivity. Such simulations are based on ...

  6. Fiber-optical accelerometers based on polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Stefani, Alessio; Bang, Ole;

    2010-01-01

    Fiber-optical accelerometers based on polymer optical fiber Bragg gratings (FBGs) are reported. We have written 3mm FBGs for 1550nm operation, characterized their temperature and strain response, and tested their performance in a prototype accelerometer.......Fiber-optical accelerometers based on polymer optical fiber Bragg gratings (FBGs) are reported. We have written 3mm FBGs for 1550nm operation, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

  7. Health monitoring of the Saint-Jean bridge of Bordeaux, France using fiber Bragg grating extensometers

    Science.gov (United States)

    Magne, Sylvain; Boussoir, Jonathan; Rougeault, Stephane; Marty-Dewynter, Veronique; Ferdinand, Pierre; Bureau, Lionel

    2003-07-01

    Most civil engineering structures have been built in the 50's and 60's and reach similar level of degradation accelerated by loading conditions and corrosion. In Europe, National Authorities and the European Commission promote Health Monitoring concepts, instrumentation of existing structures and help in the design of new durable structures of higher performance. In this context, the CEA-List has achieved a non-exclusive industrial transfer of its Bragg grating sensing technology for civil engineering applications to Hydrolog (French SME), supported by the European Community and the french ministry of Industry. In order to check the reliability and user-friendliness of this instrumentation, eleven spectrally-multiplexed Bragg grating-based extensometers, four FBG temperature sensors and an acquisition unit have been installed into the Saint-Jean bridge in Bordeaux, France with the help of the Infrastructure Regional Direction (DRE-Aquitaine) and the Bordeaux Authority (Communaute Urbaine de Bordeaux). A standardized loading of the bridge has been performed on October 29, 1001, with the purpose of correlating its mechanical reaction to loading conditions. Moreover, the equipment has been operating for one year to take into account the winter-summer cycle.

  8. Flextensional fiber Bragg grating-based accelerometer for low frequency vibration measurement

    Institute of Scientific and Technical Information of China (English)

    Jinghua Zhang; Xueguang Qiao; Manli Hu; Zhongyao Feng; Hong Gao; Yang Yang; Rui Zhou

    2011-01-01

    @@ The intelligent structural health monitoring method,which uses a fiber Bragg grating(FBG)sensor,is a new approach in the field of civil engineering.However,it lacks a reliable FBG-based accelerometer for taking structural low frequency vibration measurements.In this letter,a flextensional FBG-based accelerometer is proposed and demonstrated.The experimental results indicate that the natural frequency of the developed accelerometer is 16.7 Hz,with a high sensitivity of 410.7 pm/g.In addition,it has a broad and flat response over low frequencies ranging from 1 to 10 Hz.The natural frequency and sensitivity of the accelerometer can be tuned by adding mass to tailor the sensor performance to specific applications.Experimental results are presented to demonstrate the good performance of the proposed FBG-based accelerometer.These results show that the proposed accelerometer is satisfactory for low frequency vibration measurements.%The intelligent structural health monitoring method, which uses a fiber Bragg grating {FBG} sensor, ie a new approach in the field of civil engineering. However, it lacks a reliable FBG-based accelerometer for taking structural low frequency vibration measurements. In this letter, a flextensional FBG-based accelerometer is proposed and demonstrated. The experimental results indicate that the natural frequency of the developed accelerometer is 16.7 Hz, with a high sensitivity of 410.7 pm/g. In addition, it has a broad and flat response over low frequencies ranging from 1 to 10 Hz. The natural frequency and sensitivity of the accelerometer can be tuned by adding mass to tailor the sensor performance to specific applications. Experimental results are presented to demonstrate the good performance of the proposed FBG-based accelerometer. These results show that the proposed accelerometer is satisfactory for low frequency vibration measurements.

  9. Numerical Analysis of Thermal Dependence of the Spectral Response of Polymer Optical Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Hisham K. Hisham

    2016-06-01

    Full Text Available The thermal dependence of the spectral response (i.e. transmission, reflection and time delay (r responses of uniform polymer optical fiber (POF Bragg gratings has been investigated. In addition to the temperature dependence, the effects of grating strength (kLg and fiber index modulation (n have been investigated. Besides high capability of tunable wavelength due to the unique large and negative thermo-optic coefficient of POF, the spectral response for POF Bragg gratings show high stability and larger spectrum bandwidth with temperature variation compare with the silica optical fiber (SOF Bragg gratings, especially with the increase of the kLg value. It was found that by increasing kLg, the peak reflectance value increases and the bandwidth of the Bragg reflector become narrower. Also it’s shown by increasing the kLg value, r deceasing significantly and reach its minimum value at the designed wavelength (B. Furthermore, the r for POF Bragg gratings is less than that for SOF Bragg gratings at the same value of kLg. Also it’s found that the peak reflectivity value increases to around 60% when the n value increases from 110-4 to 510-4.

  10. Response of some pi-phase-shifted Bragg gratings to elevated pressure

    Science.gov (United States)

    Bal, Harpreet K.; Dragomir, Nicoleta M.; Sidiroglou, Fotios; Wade, Scott A.; Baxter, Greg W.; Collins, Stephen F.

    2011-05-01

    The effect of pressures up to 200 kPa on pi-phase-shifted Bragg gratings was investigated in several types of fibers placed in a pressure chamber. Standard and alternative types of pi-phase shifted gratings were studied, and changes in reflection spectra caused by pressure changes were monitored. The alternative pi-phase shifted grating was fabricated using a phase mask with 536-nm pitch exhibiting features at twice the Bragg wavelength near 1552 nm due to the interleaved refractive index modulations along the fiber core with the periodicity of the phase mask. The three gratings studied exhibited quite different variation in Bragg wavelength with increased pressure for the different fiber types, and the alternative pi-phase-shifted grating in Corning HI 1060 FLEX fiber also suffered a significant change in the shape of the peaks.

  11. Engineering approach to in-situ bridge health monitoring with fiber bragg gratings

    Institute of Scientific and Technical Information of China (English)

    WU Zhan-jun; ZHANG Bo-ming; WAN Li-bing; ZHOU Zhi; OU Jin-ping

    2006-01-01

    In this presentation the feasibility and capability of fiber Bragg gratings (FBG) employed in bridge health monitoring are demonstrated on a real bridge. FBG's wavelength shift depending on strain variance has been tested. The technique of FBG installation on bridges has been developed. 12 FBG strain sensors and 3temperature sensors have been successfully embedded in the prestressed concrete box girder during the construction of Heilongjiang Hulan River Bridge. The prestressing tension process and quasi-static loading process of the girder were monitored with those sensors before it was installed onto the bridge. After the bridge was completed,the FBG sensors embedded have been utilized to monitor the strain shift of the beam under quasi-static load,traffic load and temperature. The results show that the traffic fluxes, possible fatigue damage and deflection of the bridge can be revealed conveniently through strain measurements with these FBG sensors, which provide key information for structural health diagnosis. The fact that the FBG strain sensors have withstood the ordeal of harsh construction process and lasted for more than one year proves that their durability and stability can satisfy the requirements for bridge health monitoring. It is also shown that the FBG strain sensor is more adaptive to long-term structural health monitoring than the electric resistance strain gauge.

  12. A Fiber Bragg Grating—Bimetal Temperature Sensor for Solar Panel Inverters

    OpenAIRE

    Mohd Afiq Ismail; Nizam Tamchek; Muhammad Rosdi Abu Hassan; Dambul, Katrina D.; Jeyraj Selvaraj; Nasrudin Abd Rahim; Seyed Reza Sandoghchi; Faisal Rafiq Mahamd Adikan

    2011-01-01

    This paper reports the design, characterization and implementation of a Fiber Bragg Grating (FBG)-based temperature sensor for an Insulted-Gate Bipolar Transistor (IGBT) in a solar panel inverter. The FBG is bonded to the higher Coefficient of Thermal Expansion (CTE) side of a bimetallic strip to increase its sensitivity. Characterization results show a linear relationship between increasing temperature and the wavelength shift. It is found that the sensitivity of the sensor can be categorize...

  13. Intensity Modulation of Hybrid Soliton Pulsed Source with Fibre Bragg Grating External Cavity

    Institute of Scientific and Technical Information of China (English)

    Nuran Dogru; M.Sadettin Ozyazici

    2004-01-01

    Resonance peak spectral splitting (RPSS) in the intensity modulation of a hybrid soliton pulsed source, where fibre Bragg gratings are used as an external cavity, can be suppressed by introducing a suitable linear chirp rate in a Gaussian apodized grating. Antireflection-coated reflectivity and gain suppression factor does not strongly affect the RPSS.

  14. Bragg Gratings in Crystalline Waveguides Fabricated by Focused Ion Beam Milling

    NARCIS (Netherlands)

    Inurrategi, I.; Ay, F.; Geskus, D.; Aravazhi, S.; Gadgil, V.J.; Wörhoff, K.; Pollnau, M.

    2010-01-01

    Results of an optimization study of deeply-etched Bragg gratings in KY(WO4)2:Yb3+ to obtain photonic cavity structures are reported. By optimizing parameters such as dose per area, dwell time and pixel resolution the redeposition effects are minimized and 4.3um-deep gratings are achieved.

  15. Coherent propagation of a short polarised radiation pulse in a one-dimensional resonance Bragg grating

    NARCIS (Netherlands)

    Maimistov, A. I.; Polikarpov, V. V.

    2006-01-01

    The propagation of an optical ultrashort pulse in a resonance Bragg grating is considered taking into account the polarisation of electromagnetic radiation. It is assumed that the grating is formed by thin films containing two-level atoms with the triply degenerate upper energy level. The system of

  16. 870nm Bragg grating in single mode TOPAS microstructured polymer optical fibre

    DEFF Research Database (Denmark)

    Yuan, Wu; Webb, David J.; Kalli, Kyriacos;

    2011-01-01

    We report the fabrication and characterization of a fiber Bragg grating (FBG) with 870 nm resonance wavelength in a single-mode TOPAS microstructured polymer optical fiber (mPOF). The grating has been UV-written with the phase-mask technique using a 325 nm HeCd laser. The static tensile strain se...

  17. Direct Writing of Fiber Bragg Grating in Microstructured Polymer Optical Fiber

    DEFF Research Database (Denmark)

    Stefani, Alessio; Stecher, Matthias; Town, G. E.;

    2012-01-01

    We report point-by-point laser direct writing of a 1520-nm fiber Bragg grating in a microstructured polymer optical fiber (mPOF). The mPOF is specially designed such that the microstructure does not obstruct the writing beam when properly aligned. A fourth-order grating is inscribed in the m...

  18. Accuracy of needle position measurements using fiber Bragg gratings.

    Science.gov (United States)

    Henken, Kirsten; Van Gerwen, Dennis; Dankelman, Jenny; Van Den Dobbelsteen, John

    2012-11-01

    Accurate placement of the needle tip is essential in percutaneous therapies such as radiofrequency ablation (RFA) of liver tumors. Use of a robotic system for navigating the needle could improve the targeting accuracy. Real-time information on the needle tip position is needed, since a needle deflects during insertion in tissue. Needle shape can be reconstructed based on strain measurements within the needle. In the current experiment we determined the accuracy with which the needle tip position can be derived from strain measurements using Fiber Bragg Gratings (FBGs). Three glass fibers equipped with two FBGs each were incorporated in a needle. The needle was clamped at one end and deformed by applying static radial displacements at one or two locations. The FBG output was used for offline estimation of the needle shape and tip position. During deflections of the needle tip up to 12.5 mm, the tip position was estimated with a mean accuracy of 0.89 mm (std 0.42 mm). Adding a second deflection resulted in an error of 1.32 mm (std 0.48 mm). This accuracy is appropriate for applications such as RFA of liver tumors. The results further show that the accuracy can be improved by optimizing the placement of FBGs. PMID:22455615

  19. Experimental Investigation on Acousto-Ultrasonic Sensing Using Polarization-Maintaining Fiber Bragg Gratings

    Science.gov (United States)

    Wang, Gang; Banks, Curtis E.

    2015-01-01

    This report discusses the guided Lamb wave sensing using polarization-maintaining (PM) fiber Bragg grating (PM-FBG) sensor. The goal is to apply the PM-FBG sensor system to composite structural health monitoring (SHM) applications in order to realize directivity and multi-axis strain sensing capabilities while using reduced number of sensors. Comprehensive experiments were conducted to evaluate the performance of the PM-FBG sensor in a composite panel structure under different actuation frequencies and locations. Three Macro-Fiber-Composite (MFC) piezoelectric actuators were used to generate guided Lamb waves and they are oriented at 0, 45, and 90 degrees with respect to PM-FBG axial direction, respectively. The actuation frequency was varied from 20kHz to 200kHz. It is shown that the PM-FBG sensor system is able to detect high-speed ultrasound waves and capture the characteristics under different actuation conditions. Both longitudinal and lateral strain components in the order of nano-strain were determined based on the reflective intensity measurement data from fast and slow axis of the PM fiber. It must be emphasized that this is the first attempt to investigate acousto-ultrasonic sensing using PM-FBG sensor. This could lead to a new sensing approach in the SHM applications.

  20. Experimental investigation on acousto-ultrasonic sensing using polarization-maintaining fiber Bragg gratings

    Science.gov (United States)

    Banks, Curtis E.; Wang, Gang

    2016-04-01

    This report discusses the guided Lamb wave sensing using polarization-maintaining (PM) fiber Bragg grating (PM-FBG) sensor. The goal is to apply the PM-FBG sensor system to composite structural health monitoring (SHM) applications in order to realize directivity and multi-axis strain sensing capabilities while reducing the number of sensors. Comprehensive experiments were conducted to evaluate the performance of the PM-FBG sensor attached to a composite panel structure under different actuation frequencies and locations. Three Macro-Fiber-Composite (MFC) piezoelectric actuators were used to generate guided Lamb waves that were oriented at 0, 45, and 90 degrees with respect to PMFBG axial direction, respectively. The actuation frequency was varied from 20 kHz to 200 kHz. It was shown that the PM-FBG sensor system was able to detect high-speed ultrasound waves and capture the characteristics under different actuation conditions. Both longitudinal and lateral strain components in the order of nano-strain were determined based on the reflective intensity measurement data from fast and slow axis of the PM fiber. It must be emphasized that this is the first attempt to investigate acouto-ultrasonic sensing using PM-FBG sensor. This could lead to a new sensing approach in the SHM applications.

  1. [INVITED] Tilted fiber grating mechanical and biochemical sensors

    Science.gov (United States)

    Guo, Tuan; Liu, Fu; Guan, Bai-Ou; Albert, Jacques

    2016-04-01

    The tilted fiber Bragg grating (TFBG) is a new kind of fiber-optic sensor that possesses all the advantages of well-established Bragg grating technology in addition to being able to excite cladding modes resonantly. This device opens up a multitude of opportunities for single-point sensing in hard-to-reach spaces with very controllable cross-sensitivities, absolute and relative measurements of various parameters, and an extreme sensitivity to materials external to the fiber without requiring the fiber to be etched or tapered. Over the past five years, our research group has been developing multimodal fiber-optic sensors based on TFBG in various shapes and forms, always keeping the device itself simple to fabricate and compatible with low-cost manufacturing. This paper presents a brief review of the principle, fabrication, characterization, and implementation of TFBGs, followed by our progress in TFBG sensors for mechanical and biochemical applications, including one-dimensional TFBG vibroscopes, accelerometers and micro-displacement sensors; two-dimensional TFBG vector vibroscopes and vector rotation sensors; reflective TFBG refractometers with in-fiber and fiber-to-fiber configurations; polarimetric and plasmonic TFBG biochemical sensors for in-situ detection of cell, protein and glucose.

  2. Tunable channel drop filters consisting of a tilted Bragg grating and a mode sorting polymer waveguide.

    Science.gov (United States)

    Park, Tae-Hyun; Shin, Jin-Soo; Huang, Guanghao; Chu, Woo-Sung; Oh, Min-Cheol

    2016-03-21

    Optical wavelength filters with large tuning range and narrow bandwidth are crucial for enhancing the capability of WDM communication systems. A polymeric tunable filter for C-band, comprising a tilted Bragg grating and a mode sorting waveguide junction is proposed in this work. For dropping a certain wavelength signal, the tilted Bragg grating reflects an odd mode into an even mode and then the reflected even mode propagates towards an output port of the asymmetric Y-junction due to the mode sorting. Consequently, the output port is separated from the input port, which is not possible in an ordinary Bragg reflector. The tilted Bragg reflector with an odd-even mode coupling efficiency of 61% exhibited a maximum reflectivity of 95% for a grating of 6 mm. A linear wavelength tuning of over 10 nm was achieved for an applied thermal power of 312 mW.

  3. A strain-induced birefringent double-clad fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    Lijun Li; Lei Sun; Wande Fan; Zhi Wang; Jianhua Luo; Shenggui Fu; Shuzhong Yuan; Xiaoyi Dong

    2005-01-01

    @@ A strain-induced birefringence double-clad (DC) fiber Bragg grating (FBG) is proposed and demonstrated.The grating is fabricated in the core of rectangular inner cladding double clad fiber by using phase mask method. By applying lateral strain on the grating, the birefringence is induced. In order to detect the birefringent effect of the grating, we use it as the output mirror of a laser. When lateral strain is applied,the grating becomes birefringent. Therefore, one reflection peak of double-clad fiber Bragg grating becomes two peaks and the laser also lases in two wavelengths. The wavelength spacing of the laser can be tuned from 0 to 0.8 nm. The absolute wavelengths for the two polarizations can be tuned 1.2 and 2.0 nm,respectively.

  4. Fiber Bragg gratings in heterogeneous multicore fiber for directional bending sensing

    Science.gov (United States)

    Zhang, Hailiang; Wu, Zhifang; Shum, Perry Ping; Wang, Ruoxu; Quyen Dinh, Xuan; Fu, Songnian; Tong, Weijun; Tang, Ming

    2016-08-01

    We present the fabrication of fiber Bragg gratings (FBGs) in a trench-assisted heterogeneous multicore fiber (MCF). Two obviously different Bragg reflection peaks are obtained due to the slight difference of refractive indices between the center core and the outer cores. To investigate the reflections of the two FBGs simultaneously, only a segment of multimode fiber is inserted between the lead-in single mode fiber and the MCF. The experimental results confirm that the curvature sensitivity of the FBG in the outer core is a sinusoidal function of the bending orientation angle. The maximum linear curvature sensitivity is about 0.128 nm/m‑1. The cross sensitivity to temperature or externally applied axial strain can be eliminated by discriminating the different responses of FBGs inscribed in outer cores and the center core. Thus this MCF with FBGs can be utilized as a directional bending sensor. Moreover, the proposed sensor offers several advantages, such as low cost and flexibility in fabrication.

  5. Multiband processing of multimode light: combining 3D photonic lanterns with waveguide Bragg gratings

    OpenAIRE

    Spaleniak, Izabela; Gross, Simon; Jovanovic, Nemanja; Williams, Robert J.; Lawrence, Jon S.; Ireland, Michael J.; Withford, Michael J.

    2013-01-01

    The first demonstration of narrowband spectral filtering of multimode light on a 3D integrated photonic chip using photonic lanterns and waveguide Bragg gratings is reported. The photonic lanterns with multi-notch waveguide Bragg gratings were fabricated using the femtosecond direct-write technique in boro-aluminosilicate glass (Corning, Eagle 2000). Transmission dips of up to 5 dB were measured in both photonic lanterns and reference single-mode waveguides with 10.4-mm-long gratings. The res...

  6. Fiber Bragg grating with polyimide-silica hybrid membrane for accurately monitoring cell growth and temperature in a photobioreactor.

    Science.gov (United States)

    Zhong, Nianbing; Liao, Qiang; Zhu, Xun; Zhao, Mingfu

    2014-09-16

    A microstructured fiber Bragg grating (MSFBG) was created to accurately and simultaneously monitor the cell growth of photosynthetic bacteria (PSB) Rhodopseudomonas palustris CQK 01 and the temperature in a photobioreactor. The proposed sensor was made from an FBG unit that was separated into three regions, an unperturbed region, and two etched regions with smooth surfaces. The unperturbed grating region was employed to monitor the temperature. To eliminate the effects of the liquid concentration and temperature on the biomass, a polyimide-silica hybrid membrane was created and coated on an etched grating region to separate the liquids from the PSB; that is, this thinned region was developed to analyze the liquid concentration and temperature. Another etched grating region with a smaller diameter was used to determine the response to the temperature, biomass, and liquid concentration. In addition, two models were also presented to demonstrate accurate simultaneous measurement of the biomass and temperature. We discovered that the MSFBG sensor can rapidly and accurately determine the difference in the Bragg wavelength shifts caused by changes in the temperature, biomass, and liquid-phase concentration. The measured biomass is highly correlated with the real cell growth, with a correlation of 0.9438; the hydrogen production rate and temperature difference from metabolic heat production reached 1.97 mmol/L/h and 2.8 °C, respectively, in the PSB culture. PMID:25166743

  7. Analysis of sampled fiber Bragg gratings in polarization-maintaining fiber

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A novel type of sampled fiber Bragg gratings (FBGs) written in polarization-maintaining fiber (PMF) is proposed.The reflection spectrum,time delay,and group velocity dispersion (GVD) of the gratings are analyzed.In addition,the reflection spectrum is optimized by apodization.The scheme of multi-wavelength output based on the gratings is proposed,which could be used as a multi-wavelength polarization filter in the density wavelength division multiplexed (DWDM) system.

  8. A novel dual-wavelength fiber Bragg grating and its application in fiber ring laser

    Institute of Scientific and Technical Information of China (English)

    姜莉; 张东生; 董兴法; 开桂云; 董孝义

    2004-01-01

    A novel method for fabricating dual-wavelength fiber Bragg gratings (FBGs) by using one phase mask is developed. The method is based on a double-exposure technique. Our technique lends itself to writing gratings with controllable reflectivity and separation of two Bragg wavelengths. A grating with two equal transmission peaks of 20.25 dB is obtained by this method and the separation of the two Bragg wavelengths is about 0.8 nm. With the grating, we demonstrate a dual-wavelength erbium-doped fiber ring laser whose interval of the two peaks is 0.8 nm. The laser's peak powers can get 3.1 mW above and have a good stability.

  9. Characteristics of Bragg Gratings in All-Solid Photonic Bandgap Fiber

    Institute of Scientific and Technical Information of China (English)

    Bai-Ou Guan; Zhi Wang; Yang Zhang; Da Chen

    2008-01-01

    We report on fiber Bragg gratings in all-solid photonie bandgap fiber that was composed of a triangular array of high-index Ge-doped rods in pure silica background with fluorine-doped index-depressed layer surrounding the Ge-doped rod. Fiber Bragg gratings were photowritten with 193 nm ArF excimer laser and characterized for their response to strain, temperature, bending, and torsion. These gratings couple light from the forward core mode to not only backward core mode but also backward rod modes. This results in multiple resonance peaks in the reflection spectrum. All resonance wavelengths exhibited the same temperature and strain response with coefficient similar to that of Bragg gratings in standard single-mode fiber. The strength of the resonance peaks corresponding to the backward rod modes showed high sensitivity to bending and torsion.

  10. Femtosecond laser inscribed Bragg gratings in gold-coated fiber for space application

    Science.gov (United States)

    Wang, Qiaoni; Yang, Yuanhong; He, Jun; Wang, Yiping

    2015-09-01

    We reported a Bragg grating inscribed in gold-coated fiber (FBG) by NIR femtosecond laser (fs) for space application. Gold coating can shield the FBG from ultraviolet radiation and oxygen atom erosion. Cryogenic test, high temperature test, and gamma irradiation test were carried out. The reflectivity of the H2-free FBG remained stable at +/- 120 °C for 100 h or with 50.4 krad γ irradiation, and the central wavelength shifted within 5 pm and 1.6 pm respectively. Regeneration of the fs-FBG was observed in case the FBG was annealed at 800 °C for 5 h, and the remained 5% in reflectivity after 19 h. Such fs-FBGs inscribed in gold-coated fiber could be employed as high performance fiber sensors for space application.

  11. Study on Multiplexing Ability of Identical Fiber Bragg Gratings in a Single Fiber

    Institute of Scientific and Technical Information of China (English)

    LIU Jiansheng; ZHANG Jing; LI Xin; ZHENG Zheng

    2011-01-01

    The multiplexing ability of a novel multiplexing fiber Bragg grating(FBG)method based on Optical Time Domain Reflecto meter(OTDR)and Time Division Multiplexing TDM technologies has been theoretically analyzed and studied.This method permits the interrogation of hundreds of identical FBGs with low reflectivity in a single fiber,making the FBG sensors more applicable in the aerospace health monitoring engineering.The analysis shows that the multiplexing ability can be greatly improved if the FBG reflectivity is sufficiently low.And hence,an inexpensive large-scale distributed sensing system based on this method can be realized.When evaluating the multiplexing ability of this system,we propose for the first time that the interference effect of multi-reflections among FBGs should be taken into consideration.

  12. Field Deployable Fiber Bragg Grating Strain Patch for Long-Term Stable Health Monitoring Applications

    Directory of Open Access Journals (Sweden)

    Gerhard Kalinka

    2013-01-01

    Full Text Available A fiber Bragg grating (FBG strain patch specially adapted for long-term and high-strain applications has been developed and characterized. The design concept for the patch is based on a glass-fiber reinforced plastic (gfrp carrier material. The developed concept for the FBG integration into the carrier material was derived from reliable integration procedure of FBG sensors into composite structures. The patches’ temperature sensitivity, strain gauge factor, fiber–matrix interface adhesion and fatigue behavior were characterized. As a result, FBG strain patches with linear temperature and strain behavior, as well as excellent fatigue resistance, were developed and can be used as part of a monitoring system for advanced composite materials in aerospace structures or wind turbine power plants.

  13. High-temperature measurement using Cu-plating fiber Bragg grating for metal smart structure applications

    Science.gov (United States)

    Chang, Tianying; Jia, Lei; Sui, Qingmei; Cui, Hong-Liang

    2014-03-01

    High-temperature experiments for electroless Cu-plating Fiber Bragg Grating (FBG) indicate that Cu-plating FBG can measure high-temperature up to (even beyond) 300°C and it has high linearity, accuracy and repeatability. We can control Cu-plating FBG's temperature sensitivity by controlling plating layer's thickness. Temperature sensitivity of FBG with Cu-plating can be improved by more than three times with no less than 300μmthick coating by electroless and electrical Cu-plating. Such FBG can be soldered onto metal structures to get good bonding with the structure. As a result, such fiber sensors can get good protection, and high-temperature monitoring of smart structure is obtained.

  14. Health monitoring of Binzhou Yellow River highway bridge using fiber Bragg gratings

    Science.gov (United States)

    Ou, Jinping; Zhao, Xuefeng; Li, Hui; Zhou, Zhi; Zhang, Zhichun; Wang, Chuan

    2005-05-01

    Binzhou yellow river Highway Bridge with 300 meter span and 768 meter length is located in the Shandong province of China and is the first cable stayed bridge with three towers along the yellow river, one of the biggest rivers in China. In order to monitoring the strain and temperature of the bridge and evaluate the health condition, one fiber Bragg grating sensing network consists of about one hundred and thirty FBG sensors mounted in 31 monitoring sections respectively, had been built during three years time. Signal cables of sensors were led to central control room located near the main tower. One four-channel FBG interrogator was used to read the wavelengths from all the sensors, associated with four computer-controlled optic switches connected to each channel. One program was written to control the interrogator and optic switches simultaneously, and ensure signal input precisely. The progress of the monitoring can be controlled through the internet. The sensors embedded were mainly used to monitor the strain and temperature of the steel cable and reinforced concrete beam. PE jacket opening embedding technique of steel cable had been developed to embed FBG sensors safely, and ensure the reliability of the steel cable opened at the same time. Data obtained during the load test can show the strain and temperature status of elements were in good condition. The data obtained via internet since the bridge's opening to traffic shown the bridge under various load such as traffic load, wind load were in good condition.

  15. Simultaneous measurement of strain and temperature by two peanut tapers with embedded fiber Bragg grating.

    Science.gov (United States)

    Lv, Lingya; Wang, Sumei; Jiang, Lan; Zhang, Fei; Cao, Zhitao; Wang, Peng; Jiang, Yi; Lu, Yongfeng

    2015-12-20

    A compact optical fiber sensor for simultaneous measurement of strain and temperature is designed and experimentally investigated. The proposed sensor consists of a two-peanut-taper Mach-Zehnder interferometer (MZI) and in-line embedded fiber Bragg grating (FBG). The sensor at a length of 35 mm presents strain sensitivities 1.07  pm/με and 0.891  pm/με, the temperature sensitivities are 55.35  pm/°C and 10.85  pm/°C, for MZI and FBG, respectively. Through tapering the center of the sensor by a fusion splicer, the strain sensitivity of the MZI is improved to 1.93  pm/με. The resolutions for strain and temperature measurement are ±3.104  με and ±0.194°C with the wavelength resolution of 5 pm. The experimental results show that the sensor is able to simultaneously measure strain and temperature by sensitivity matrix with advantages such as simple structure, compact size, ease of fabrication, low cost, etc. PMID:26837035

  16. Adaptive Integrated Optical Bragg Grating in Semiconductor Waveguide Suitable for Optical Signal Processing

    Science.gov (United States)

    Moniem, T. A.

    2016-05-01

    This article presents a methodology for an integrated Bragg grating using an alloy of GaAs, AlGaAs, and InGaAs with a controllable refractive index to obtain an adaptive Bragg grating suitable for many applications on optical processing and adaptive control systems, such as limitation and filtering. The refractive index of a Bragg grating is controlled by using an external electric field for controlling periodic modulation of the refractive index of the active waveguide region. The designed Bragg grating has refractive indices programmed by using that external electric field. This article presents two approaches for designing the controllable refractive indices active region of a Bragg grating. The first approach is based on the modification of a planar micro-strip structure of the iGaAs traveling wave as the active region, and the second is based on the modification of self-assembled InAs/GaAs quantum dots of an alloy from GaAs and InGaAs with a GaP traveling wave. The overall design and results are discussed through numerical simulation by using the finite-difference time-domain, plane wave expansion, and opto-wave simulation methods to confirm its operation and feasibility.

  17. Bandwidth-Tunable Fiber Bragg Gratings Based on UV Glue Technique

    Science.gov (United States)

    Fu, Ming-Yue; Liu, Wen-Feng; Chen, Hsin-Tsang; Chuang, Chia-Wei; Bor, Sheau-Shong; Tien, Chuen-Lin

    2007-07-01

    In this study, we have demonstrated that a uniform fiber Bragg grating (FBG) can be transformed into a chirped fiber grating by a simple UV glue adhesive technique without shifting the reflection band with respect to the center wavelength of the FBG. The technique is based on the induced strain of an FBG due to the UV glue adhesive force on the fiber surface that causes a grating period variation and an effective index change. This technique can provide a fast and simple method of obtaining the required chirp value of a grating for applications in the dispersion compensators, gain flattening in erbium-doped fiber amplifiers (EDFAs) or optical filters.

  18. Fused-silica sandwiched three-port grating under second Bragg angle incidence

    Science.gov (United States)

    Li, Hongtao; Wang, Bo; Pei, Hao; Chen, Li; Lei, Liang; Zhou, Jinyun

    2016-05-01

    The fused-silica sandwiched three-port grating under second Bragg angle incidence is presented with operation in transmission. To obtain a highly-efficient three-port grating for a working wavelength of 800 nm, the grating depth and period should be optimized by using rigorous coupled-wave analysis. With the optimized different three-port grating depths and periods, both TE-polarized and TM-polarized waves can be diffracted into three orders with nearly 33% efficiency for the given duty cycle of 0.6. Based on the grating parameters of numerical optimization, modal method may be employed to explain the physical mechanism of the beam propagation in the grating and analyze the splitting behavior. For the sandwiched three-port grating, it is feasible that the diffraction efficiencies can be enhanced for both TE and TM polarizations.

  19. Numerical investigation of slow solitons in Bragg gratings with a hyperbolic tangent apodization

    International Nuclear Information System (INIS)

    This paper numerically and analytically investigates the formation and propagation motion of optical soliton in the Bragg grating. We choose the fibre Bragg grating with hyperbolic tangent apodization in the middle section in order to obtain slower solitons. Optical fibre soliton but not Bragg grating soliton is used as input pulse in the discussion, which is much more approximate to the light source for the practical purpose. We discuss in detail the effects of the soliton's velocity with some parameters in the process of transmission. The results show that by choosing special parameters, one can make the soliton slow-down with a little distortion and energy decay and obtain tunable time-delay on a small scale. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  20. Numerical investigation of slow solitons in Bragg gratings with a hyperbolic tangent apodization

    Institute of Scientific and Technical Information of China (English)

    Wang Kui-Ru; Cheng Jie-Lin; Sang Xin-Zhu; Chen Gong

    2011-01-01

    This paper numerically and analytically investigates the formation and propagation motion of optical soliton in the Bragg grating. We choose the fibre Bragg grating with hyperbolic tangent apodization in the middle section in order to obtain slower solitons. Optical fibre soliton but not Bragg grating soliton is used as input pulse in the discussion, which is much more approximate to the light source for the practical purpose. We discuss in detail the effects of the soliton's velocity with some parameters in the process of transmission. The results show that by choosing special parameters, one can make the soliton slow-down with a little distortion and energy decay and obtain tunable time-delay on a small scale.

  1. Fiber Bragg Gratings in Small-Core Ge-Doped Photonic Crystal Fibers

    Institute of Scientific and Technical Information of China (English)

    Yiping Wang; Hartmut Bartelt; Wolfgang Ecke; Reinhardt Willsch; Jens Kobelke; Michael Kautz; Sven Brueckner; Manfred Rothhardt

    2008-01-01

    This paper reports fiber Bragg gratings (FBGs) inscribed in a small-core Ge-doped photonic crystal fibers with a UV laser and a Talbot inter-ferometer. The responses of such FBGs to temper-ature, strain, bending, and transverse-loading were systematically investigated. The Bragg wavelength of the FBGs shifts toward longer wavelengths with increasing temperature, tensile strain, and trans-verse-loading. The bending and transverse- loading properties of the FBGs are sensitive to the fiber orientations.

  2. PROTECTIVE COATINGS OF FIBER BRAGG GRATING FOR MINIMIZING OF MECHANICAL IMPACT ON ITS WAVELENGTH CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    A. S. Munko

    2015-03-01

    Full Text Available The paper deals with the scheme for the study of the Bragg wavelength shift dependence on the applied tensile force. Samples of fiber Bragg gratings with different coatings have been studied: the restored acrylate coating, the heatshrinkable fusion splice protection sleeve without metal rod, the heat-shrinkable fusion splice protection sleeve with a metal rod, the metal capillary, polyvinylchloride tube. For different coatings of diffractive structure, dependences of wavelength shift for the Bragg grating resonance have been obtained on the tensile strength applied to the ends of an optical fiber. It was determined that the studied FBG coatings give the possibility to reduce the mechanical impact on the Bragg wavelength shift for 1.1-15 times as compared to an uncoated waveguide. The most effective version of coated fiber Bragg grating is the heatshrinkable fusion splice protection sleeve with a metal rod. When the force (equal to 6 N is applied to the 100 mm optical fiber area with the inscribed diffractive structure, the Bragg wavelength shift is 7.5 nm for the unprotected sample and 0.5 nm for the one coated with the heat-shrinkable fusion splice protection sleeve.

  3. A flat microwave photonic filter based on M-Z modulatorand fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    QI Chun-hui; PEI Li; NING Ti-gang; GUO Lan; WU Shu-qiang; ZHAO Rui-feng; RUAN Yi

    2009-01-01

    A new multiple-taps and flat microwave photonic filter, which is composed of fiber Bragg grating, M-Z modulator and erbium-doped fiber, is put forward. The flat band-pass or flat band-stop response can be realized by adjusting the coupler's factor and the reflectivity of the fiber Bragg grating or the gain of the erbium-doped fiber. The free spectral range of the filter can be tuned by controlling the length of the erbium-doped fiber. The potential and feasibility of the proposed filtering structures have been demonstrated by simulation.

  4. Direct UV written planar Bragg gratings that feature zero fluence induced birefringence

    Science.gov (United States)

    Holmes, Christopher; Cooper, Peter A.; Fernando, Harendra N. J.; Stroll, Andreas; Gates, James C.; Krishnan, Chirenjeevi; Haynes, Roger; Mennea, Paolo L.; Carpenter, Lewis G.; Gawith, Corin B. E.; Roth, Martin M.; Charlton, Martin D.; Smith, Peter G. R.

    2015-12-01

    Direct UV writing is a planar fabrication process capable of simultaneously defining waveguides and Bragg gratings. The technique is fully computer controlled and uniquely uses a small focused spot ~7 μm in diameter for direct writing exposure. This work investigates its use to achieve phase trimming and Bragg grating definition in silica-on-silicon lithographic waveguides. It is observed that birefringence control using direct UV writing can be made independent of exposure fluence with this technique through tailoring substrate stress. The result is demonstrated experimentally and supported theoretically using finite element analysis.

  5. A Directly-Written Monolithic Waveguide-Laser Incorporating a DFB Waveguide-Bragg Grating

    CERN Document Server

    Marshall, Graham D; Ams, Martin; Piper, James A; Withford, Michael J

    2008-01-01

    We report the fabrication and performance of the first C-band directly-written monolithic waveguide-laser. The waveguide-laser device was created in an Erbium and Ytterbium doped phosphate glass host and consisted of an optical waveguide that included a distributed feedback Bragg grating structure. The femtosecond laser direct-write technique was used to create both the waveguide and the waveguide-Bragg grating simultaneously and in a single processing step. The waveguide-laser was optically pumped at approximately 980 nm and lased at 1537nm with a bandwidth of less than 4 pm.

  6. Fiber Bragg Grating-Based Performance Monitoring of Piles Fiber in a Geotechnical Centrifugal Model Test

    Directory of Open Access Journals (Sweden)

    Xiaolin Weng

    2014-01-01

    Full Text Available In centrifugal tests, conventional sensors can hardly capture the performance of reinforcement in small-scale models. However, recent advances in fiber optic sensing technologies enable the accurate and reliable monitoring of strain and temperature in laboratory geotechnical tests. This paper outlines a centrifugal model test, performed using a 60 g ton geocentrifuge, to investigate the performance of pipe piles used to reinforce the loess foundation below a widened embankment. Prior to the test, quasidistributed fiber Bragg grating (FBG strain sensors were attached to the surface of the pipe piles to measure the lateral friction resistance in real time. Via the centrifuge actuator, the driving of pipe piles was simulated. During testing, the variations of skin friction distribution along the pipe piles were measured automatically using an optical fiber interrogator. This paper represents the presentation and detailed analysis of monitoring results. Herein, we verify the reliability of the fiber optic sensors in monitoring the model piles without affecting the integrity of the centrifugal model. This paper, furthermore, shows that lateral friction resistance developed in stages with the pipe piles being pressed in and that this sometimes may become negative.

  7. Multiband processing of multimode light: combining 3D photonic lanterns with waveguide Bragg gratings

    CERN Document Server

    Spaleniak, Izabela; Jovanovic, Nemanja; Williams, Robert J; Lawrence, Jon S; Ireland, Michael J; Withford, Michael J

    2013-01-01

    The first demonstration of narrowband spectral filtering of multimode light on a 3D integrated photonic chip using photonic lanterns and waveguide Bragg gratings is reported. The photonic lanterns with multi-notch waveguide Bragg gratings were fabricated using the femtosecond direct-write technique in boro-aluminosilicate glass (Corning, Eagle 2000). Transmission dips of up to 5 dB were measured in both photonic lanterns and reference single-mode waveguides with 10.4-mm-long gratings. The result demonstrates efficient and symmetrical performance of each of the gratings in the photonic lantern. Such devices will be beneficial to space-division multiplexed communication systems as well as for units for astronomical instrumentation for suppression of the atmospheric telluric emission from OH lines.

  8. Anderson localization in a partially random Bragg grating and a conserved area theorem

    CERN Document Server

    Mafi, Arash

    2015-01-01

    We investigate the gradual emergence of the disorder-related phenomena in intermediate regimes between a deterministic periodic Bragg grating and a fully random grating and highlight two critical properties of partially disordered Bragg gratings. First, the integral of the logarithm of the transmittance over the reciprocal wavevector space is a conserved quantity. Therefore, adding disorder merely redistributes the transmittance over the reciprocal space. Second, for any amount of disorder, the average transmittance decays exponentially with the number of grating layers in the simple form of $\\exp(-\\eta N)$ for sufficiently large $N$, where $\\eta$ is a constant and $N$ is the number of layers. Conversely, the simple exponential decay form does not hold for small $N$ except for a highly disordered system. Implications of these findings are demonstrated.

  9. Optimization of the accelerated curing process of concrete using a fibre Bragg grating-based control system and microwave technology

    Science.gov (United States)

    Fabian, Matthias; Jia, Yaodong; Shi, Shi; McCague, Colum; Bai, Yun; Sun, Tong; Grattan, Kenneth T. V.

    2016-05-01

    In this paper, an investigation into the suitability of using fibre Bragg gratings (FBGs) for monitoring the accelerated curing process of concrete in a microwave heating environment is presented. In this approach, the temperature data provided by the FBGs are used to regulate automatically the microwave power so that a pre-defined temperature profile is maintained to optimize the curing process, achieving early strength values comparable to those of conventional heat-curing techniques but with significantly reduced energy consumption. The immunity of the FBGs to interference from the microwave radiation used ensures stable readings in the targeted environment, unlike conventional electronic sensor probes.

  10. Performance analysis of peak tracking techniques for fiber Bragg grating interrogation systems

    OpenAIRE

    Olivero, Massimo; Tosi, Daniele; Perrone, Guido

    2012-01-01

    In this paper, we propose a spectral correlation-based technique for tracking the wavelength shift of a fiber Bragg grating. We compared this approach, by means of a Monte Carlo numerical simulation, to the typical peak tracking techniques applied in classic interrogation systems. As result, we obtained a considerable gain in terms of noise tolerance (about 20 dB), which can be further incremented by selecting large-bandwidth gratings. This permits to increase the power budget of a fiber Brag...

  11. Anomalous thermal dynamics of Bragg gratings inscribed in germanosilicate optical fiber

    OpenAIRE

    Rahman, A.; Madhav, Venu K; B. Srinivasan; S. Asokan

    2009-01-01

    An interesting, periodic appearance of a new peak has been observed in the reflected spectrum of a Fiber Bragg Grating (FBG) inscribed in a germanosilicate fiber during thermal treatment. The new peak occurs on the longer wavelength side of the spectrum during heating and on the shorter wavelength side during cooling, following an identical reverse dynamics. Comparison with a commercial grating with 99.9% reflectivity shows a similar decay dynamics. It is proposed that the distortion due to s...

  12. Special Apodized Fiber Bragg Grating for Flat-top Band-pass Reflectivity Filter

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-min; YU Zhong-yuan; YANG Hong-bo; YANG Bo-jun; YU Li; ZHANG Xiao-guang

    2004-01-01

    The characteristics of special apodized fiber Bragg grating (FBG) in flat-top pass-band as reflectivity filter are presented. This special apodized FBG was designed by the particle swarm optimization algorithm. Compared with conventional apodized FBG, the special apodized FBG presented was more robust in the flat-top pass-band characteristic even if the strength of grating is very week. This technology is very interesting in designing the filter for wavelength division multiplexing system.

  13. Plasmonic V-groove waveguides with Bragg grating filters via nanoimprint lithography

    DEFF Research Database (Denmark)

    Smith, Cameron L. C.; Desiatov, Boris; Goykmann, Ilya;

    2012-01-01

    We demonstrate spectral filtering with state-of-the-art Bragg gratings in plasmonic V-groove waveguides fabricated by wafer scale processing based on nanoimprint lithography. Transmission spectra of the devices having 16 grating periods exhibit spectral rejection of the channel plasmon polaritons...... with effective refractive index values calculated by finite element simulations in COMSOL. The results represent advancement towards the implementation of plasmonic V-grooves with greater functional complexity and mass-production compatibility....

  14. Bragg Gratings Induced in Birefringent Optical Fiber with an Elliptical Stress Cladding

    Directory of Open Access Journals (Sweden)

    I. K. Meshkovskiy

    2013-01-01

    Full Text Available The paper presents the results of writing of type I and high-performance type II fiber Bragg gratings in birefringent optical fiber with an elliptical stress cladding by a single 20 ns pulse of KrF excimer laser (248 nm. The gratings’ efficiency produced by a single pulse was up to 100%. Experimental results on visualization of these gratings are presented.

  15. Simultaneous measurement of strain, temperature and refractive index based on multimode interference, fiber tapering and fiber Bragg gratings

    Science.gov (United States)

    Oliveira, Ricardo; Osório, Jonas H.; Aristilde, Stenio; Bilro, Lúcia; Nogueira, Rogerio N.; Cordeiro, Cristiano M. B.

    2016-07-01

    We report the development of an optical fiber sensor capable of simultaneously measuring strain, temperature and refractive index. The sensor is based on the combination of two fiber Bragg gratings written in a standard single-mode fiber, one in an untapered region and another in a tapered region, spliced to a no-core fiber. The possibility of simultaneously measuring three parameters relies on the different sensitivity responses of each part of the sensor. The results have shown the possibility of measuring three parameters simultaneously with a resolution of 3.77 με, 1.36 °C and 5  ×  10‑4, respectively for strain, temperature and refractive index. On top of the multiparameter ability, the simple production and combination of all the parts involved on this optical-fiber-based sensor is an attractive feature for several sensing applications.

  16. Fast fiber Bragg grating interrogation system with scalability to support monitoring of large structures in harsh environments

    Science.gov (United States)

    Moslehi, Behzad; Black, Richard J.; Costa, Joannes M.; Edwards, Elizabeth H.; Faridian, Fereydoun; Sotoudeh, Vahid

    2014-04-01

    Fiber optic sensor systems can alleviate certain challenges faced by electronics sensors faced when monitoring structures subject to marine and other harsh environments. Challenges in implementation of such systems include scalability, interconnection and cabling. We describe a fiber Bragg grating (FBG) sensor system architecture based that is scalable to support over 1000 electromagnetic interference immune sensors at high sampling rates for harsh environment applications. A key enabler is a high performance FBG interrogator supporting subsection sampling rates ranging from kHz to MHz. Results are presented for fast dynamic switching between multiple structural sections and the use of this sensing system for dynamic load monitoring as well as the potential for acoustic emission and ultrasonic monitoring on materials ranging from aluminum and composites to concrete subject to severe environments.

  17. Fiber Bragg grating-based performance monitoring of a slope model subjected to seepage

    Science.gov (United States)

    Zhu, Hong-Hu; Shi, Bin; Yan, Jun-Fan; Zhang, Jie; Zhang, Cheng-Cheng; Wang, Bao-Jun

    2014-09-01

    In the past few years, fiber optic sensing technologies have played an increasingly important role in the health monitoring of civil infrastructures. These innovative sensing technologies have recently been successfully applied to the performance monitoring of a series of geotechnical structures. Fiber optic sensors have shown many unique advantages in comparison with conventional sensors, including immunity to electrical noise, higher precision and improved durability and embedding capabilities; fiber optic sensors are also smaller in size and lighter in weight. In order to explore the mechanism of seepage-induced slope instability, a small-scale 1 g model test of the soil slope has been performed in the laboratory. During the model’s construction, specially fabricated sensing fibers containing nine fiber Bragg grating (FBG) strain sensors connected in a series were horizontally and vertically embedded into the soil mass. The surcharge load was applied on the slope crest, and the groundwater level inside of the slope was subsequently varied using two water chambers installed besides the slope model. The fiber optic sensing data of the vertical and horizontal strains within the slope model were automatically recorded by an FBG interrogator and a computer during the test. The test results are presented and interpreted in detail. It is found that the gradually accumulated deformation of the slope model subjected to seepage can be accurately captured by the quasi-distributed FBG strain sensors. The test results also demonstrate that the slope stability is significantly affected by ground water seepage, which fits well with the results that were calculated using finite element and limit equilibrium methods. The relationship between the strain measurements and the safety factors is further analyzed, together with a discussion on the residual strains. The performance evaluation of a soil slope using fiber optic strain sensors is proved to be a potentially effective

  18. Simultaneous determination of curvature, plane of curvature, and temperature by use of a miniaturized sensing head based on fiber Bragg gratings

    Science.gov (United States)

    Araujo, F. M.; Ferreira, L. A.; Santos, J. L.

    2002-05-01

    We present what we believe to be a novel miniaturized sensor configuration based on fiber Bragg gratings for simultaneous measurement of curvature and temperature in smart structures and composite materials. Because of the particular geometry of the sensing head, it is possible not only to measure the radius of curvature but also to determine the plane of curvature. We arrange three Bragg gratings in the vertices of the smallest equilateral triangle that can be defined by the cross sections of the fibers. The set is then inserted into a glue-filled capillary stainless-steel tube to provide both suitable protection for the Bragg sensors and rotational symmetry to the sensing head. This tube also ensures isolation from axial strain, allowing for the additional determination of temperature. The proposed sensing head is particularly well suited for applications in smart structures because it can be embedded along any layer of a composite material (including the neutral line) without special concern for the relative orientation of the Bragg gratings and the composite layers. We can also use this sensing configuration to implement more-sophisticated sensors dedicated, for example, to the measurement of multiaxial acceleration or flow and temperature.

  19. Investigation of code reconfigurable fibre Bragg gratings for Optical Code Division Multiple Access (OCDMA) and Optical Packet Switching (OPS) Networks

    OpenAIRE

    Tian, Chun

    2009-01-01

    This thesis documents my work in the telecommunication system laboratory at the Optoelectronics Research Centre, towards the implementation of code reconfigurable OCDMA and all-optical packet switching nodes based on fibre Bragg grating (FBG) technology. My research work involves characterizing the performance of various gratings, specifically high reflectivity, short chip duration, long code sequences, multiple phase level and tunable superstructured fiber Bragg gratings (SSFBGs), by using t...

  20. Higher Order Diffraction Characteristics of Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Sunita P. Ugale

    2013-02-01

    Full Text Available The effect of grating saturation on higher order diffraction characteristic of FBG is investigated by using Coupled mode theory. Grating saturation effects were considered in the index distribution model showing the significant influence on the coupling process and hence on the reflectivity characteristics of FBG. Maximum reflectivity curves for first and higher order diffraction of FBG are plotted for different values of saturation coefficient. The effect of change in length and change in refractive index are studied. The behavior of grating for higher order of diffraction is totally different than first order of diffraction. In saturated gratings, the higher order diffraction can be utilized for multiparameter sensing

  1. Novel Tunable PMD Compensation Technology Using Linear Chirped Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-min; YU Zhong-yuan; YANG Hong-bo; ZHANG Xiao-guang; YANG Bo-jun

    2004-01-01

    Based on uniform fiber Bragg grating bonded with a magnetostrictive rod in the non-uniform magnetic field, a novel PMD compensation technique is proposed. This all- fiber PMD compensation technology is cost-effective and flexible in designing the differential group delay profile.

  2. Time-dependent variation of fiber Bragg grating reflectivity in PMMA-based polymer optical fibers

    DEFF Research Database (Denmark)

    Saez-Rodriguez, D.; Nielsen, Kristian; Bang, Ole;

    2015-01-01

    In this Letter, we investigate the effects of viscoelasticity on both the strength and resonance wavelength of two fiber Bragg gratings (FBGs) inscribed in microstructured polymer optical fiber (mPOF) made of undoped PMMA. Both FBGs were inscribed under a strain of 1% in order to increase...

  3. Angle dependent Fiber Bragg grating inscription in microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Bundalo, Ivan-Lazar; Nielsen, Kristian; Bang, Ole

    2015-01-01

    We report on an incidence angle influence on inscription of the Fiber Bragg Gratings in Polymethyl methacrylate (PMMA) microstructured polymer optical fibers. We have shown experimentally that there is a strong preference of certain angles, labeled Gamma K, over the other ones. Angles close...

  4. Bragg waveguide grating as a 1d photonic band gap structure: COST 268 modelling task

    NARCIS (Netherlands)

    Ctyroky, J.; Helfert, S.; Pregla, R.; Bienstman, P.; Baets, R.; Ridder, de R.; Stoffer, R.; Klaasse, G.; Petracek, J.; Lalanne, P.; Hugonin, J.P.; Rue, de la R.M.

    2002-01-01

    Modal reflection, transmission and loss of deeply etched Bragg waveguide gratings were modelled by six European laboratories using independently developed two-dimensional (2D) numerical codes based on four different methods, with very good mutual agreement. It was found that (rather weak) material d

  5. Focused ion beam nano-structuring of Bragg gratings in $Al_2O_3$ channel waveguides

    NARCIS (Netherlands)

    Ay, Feridun; Uranga, Amaia; Bradley, Jonathan D.B.; Wörhoff, Kerstin; Ridder, de René M.; Pollnau, Markus; Ridder, de R.M.; Ay, F.; Kauppinen, L.J.

    2008-01-01

    We report our recent results on an optimization study of focused ion beam (FIB) nano-structuring of Bragg gratings in $Al_2O_3$ channel waveguides. By optimizing FIB milling parameters such as ion current, dwell time, loop repetitions, scanning strategy, and applying a top metal layer for reducing c

  6. A novel tunable polarization mode dispersion compensator with strain chirped fiber Bragg gratings

    Institute of Scientific and Technical Information of China (English)

    Yumin Liu(刘玉敏); Zhongyuan Yu(俞重远); Yuan Zheng(郑远); Xiaoguang Zhang(张晓光); Bojun Yang(杨伯君)

    2004-01-01

    A tunable polarization mode dispersion (PMD) compensator based on strain-chirped fiber Bragg gratings (FBGs) is proposed. It natures in flexible designing, large tuning range, without using linear or nonlinear chirped phase mask, fast tuning response time, continuously adjustable, all-fiber based, compact, and cheap.

  7. Investigations on birefringence effects in polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Hu, Xiaolian; Saez-Rodriguez, D.; Bang, Ole;

    2014-01-01

    birefringence effects in (m)POFBGs. To achieve this, highly reflective gratings were inscribed with the phase mask technique. They were then monitored in transmission with polarized light. For this, (m)POF sections a few cm in length containing the gratings were glued to angled silica fibers. Polarization...

  8. Reconstruction of structural damage based on reflection intensity spectra of fiber Bragg gratings

    Science.gov (United States)

    Huang, Guojun; Wei, Changben; Chen, Shiyuan; Yang, Guowei

    2014-12-01

    We present an approach for structural damage reconstruction based on the reflection intensity spectra of fiber Bragg gratings (FBGs). Our approach incorporates the finite element method, transfer matrix (T-matrix), and genetic algorithm to solve the inverse photo-elastic problem of damage reconstruction, i.e. to identify the location, size, and shape of a defect. By introducing a parameterized characterization of the damage information, the inverse photo-elastic problem is reduced to an optimization problem, and a relevant computational scheme was developed. The scheme iteratively searches for the solution to the corresponding direct photo-elastic problem until the simulated and measured (or target) reflection intensity spectra of the FBGs near the defect coincide within a prescribed error. Proof-of-concept validations of our approach were performed numerically and experimentally using both holed and cracked plate samples as typical cases of plane-stress problems. The damage identifiability was simulated by changing the deployment of the FBG sensors, including the total number of sensors and their distance to the defect. Both the numerical and experimental results demonstrate that our approach is effective and promising. It provides us with a photo-elastic method for developing a remote, automatic damage-imaging technique that substantially improves damage identification for structural health monitoring.

  9. Reconstruction of structural damage based on reflection intensity spectra of fiber Bragg gratings

    International Nuclear Information System (INIS)

    We present an approach for structural damage reconstruction based on the reflection intensity spectra of fiber Bragg gratings (FBGs). Our approach incorporates the finite element method, transfer matrix (T-matrix), and genetic algorithm to solve the inverse photo-elastic problem of damage reconstruction, i.e. to identify the location, size, and shape of a defect. By introducing a parameterized characterization of the damage information, the inverse photo-elastic problem is reduced to an optimization problem, and a relevant computational scheme was developed. The scheme iteratively searches for the solution to the corresponding direct photo-elastic problem until the simulated and measured (or target) reflection intensity spectra of the FBGs near the defect coincide within a prescribed error. Proof-of-concept validations of our approach were performed numerically and experimentally using both holed and cracked plate samples as typical cases of plane-stress problems. The damage identifiability was simulated by changing the deployment of the FBG sensors, including the total number of sensors and their distance to the defect. Both the numerical and experimental results demonstrate that our approach is effective and promising. It provides us with a photo-elastic method for developing a remote, automatic damage-imaging technique that substantially improves damage identification for structural health monitoring. (paper)

  10. Shape memory polymeric composites sensing by optic fibre Bragg gratings: A very first approach

    Science.gov (United States)

    Quadrini, Fabrizio; Santo, Loredana; Ciminello, Monica; Concilio, Antonio; Volponi, Ruggero; Spena, Paola

    2016-05-01

    Shape memory polymer composites (SMPCs) have the potential for many applications in aerospace, spanning from self-repairing of structures to self-deploying of antennas, solar sails, or functional devices (e.g. for grabbing small space debris). In all these cases, it may be essential to have information about their configuration at different stages of shape recovery. In this study, the strain history of a prepreg carbon fibre system, cured with a shape memory polymer (SMP) interlayer, is monitored through a Fibre Bragg Grating (FBG), a fibre optic sensor device. SMPC has been manufactured by using traditional technologies for aerospace. After manufacturing cylindrical shape samples, an external fibre optic system is added to the composite structure; this system is especially suited for high temperatures which are necessary for SMP recovery and composite softening. Sensor functionality is checked before and after each strain history path. Optic fibre arrangement is optimized to avoid unwanted breakings whereas strains are limited by fibre collapsing, i.e. within nominal 2% of deformation. Dynamic information about shape recovery gives fundamental insights about strain evolution during time as well as its spatial distribution.

  11. Improved thermal and strain performance of annealed polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Stefani, Alessio; Bache, Morten;

    2011-01-01

    We report on a detailed study of the inscription and characterization of fiber Bragg gratings (FBGs) in commercial step index polymer optical fibers (POFs). Through the growth dynamics of the gratings, we identify the effect of UV-induced heating during the grating inscription. We found that FBGs...... in annealed commercial POFs can offer more stable short-term performance at both higher temperature and larger strain. Furthermore, the FBGs' operational temperature and strain range without hysteresis was extended by the annealing process. We identified long-term stability problem of even the annealed POF...

  12. Fiber Bragg Grating Modeling, Characterization and Optimization with different index profiles

    Directory of Open Access Journals (Sweden)

    SUNITA UGALE

    2010-09-01

    Full Text Available This paper presents the modeling and characterization of an optical fiber grating for maximum reflectivity, minimum side lobe power wastage. Grating length and refractive index profile are the critical parameters in contributing to performance of fiber Bragg grating. The reflection spectra and side lobes strength were analyzed with different lengths and different refractive index profiles. podization techniques are used to get optimized reflection spectra. The simulations are based on solving coupled mode equations by transfer matrix method that describes the interaction of guided modes.

  13. High Pressure Sensing and Dynamics Using High Speed Fiber Bragg Grating Interrogation Systems

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, G. [LANL; Sandberg, R. L. [LANL; Lalone, B. M. [NSTec; Marshall, B. R. [NSTec; Grover, M. [NSTec; Stevens, G. D. [NSTec; Udd, E. [Columbia Gorge Research

    2014-06-01

    Fiber Bragg gratings (FBGs) are developing into useful sensing tools for measuring high pressure dynamics in extreme environments under shock loading conditions. Approaches using traditional diode array coupled FBG interrogation systems are often limited to readout speeds in the sub-MHz range. For shock wave physics, required detection speeds approaching 100 MHz are desired. We explore the use of two types of FBG sensing systems that are aimed at applying this technology as embedded high pressure probes for transient shock events. Both approaches measure time resolved spectral shifts in the return light from short (few mm long) uniform FBGs at 1550 nm. In the first approach, we use a fiber coupled spectrometer to demultiplex spectral channels into an array (up to 12) of single element InGaAs photoreceivers. By monitoring the detectors during a shock impact event with high speed recording, we are able to track the pressure induced spectral shifting in FBG down to a time resolution of 20 ns. In the second approach, developed at the Special Technologies Lab, a coherent mode-locked fiber laser is used to illuminate the FBG sensor. After the sensor, wavelength-to-time mapping is accomplished with a chromatic dispersive element, and entire spectra are sampled using a single detector at the modelocked laser repetition rate of 50 MHz. By sampling with a 12 GHz InGaAs detector, direct wavelength mapping in time is recorded, and the pressure induced FBG spectral shift is sampled at 50 MHz. Here, the sensing systems are used to monitor the spectral shifts of FBGs that are immersed into liquid water and shock compressed using explosives. In this configuration, the gratings survive to pressures approaching 50 kbar. We describe both approaches and present the measured spectral shifts from the shock experiments.

  14. Development of tilted fibre Bragg gratings using highly coherent 255 nm radiation

    Indian Academy of Sciences (India)

    O Prakash; J Kumar; R Mahakud; U Kumbhkar; S V Nakhe; S K Dixit

    2014-02-01

    This paper reports the study on development of tilted fibre Bragg gratings using highly coherent 255 nm radiation, obtained from the second harmonic generation (SHG) of copper vapour laser (CVL). The transmission and reflection spectra of the tilted fibre Bragg gratings (TFBG) were studied for the tilt angles of 0° (normal FBG), 1°, 3° and 4° between the fibre axis and the interference fringe plane. It was observed that as the angle of fibre axis and phase mask increased, the main Bragg peak shifted towards the higher wavelength and transmission dip decreased. The transmission dip of the cladding mode first increased and then decreased after reaching a maximum with the increase in the tilt angle.

  15. Embossed Bragg Gratings Based on Organically Modified Silane Waveguides in InP.

    Science.gov (United States)

    Liu, J; Lam, Y L; Chan, Y C; Zhou, Y; Ooi, B S; Tan, G; Yao, J

    2000-09-20

    Considering the large variety of applications for optical glass waveguide gratings, the effective production method of embossing for micropatterning, and the unique advantages of InP-based materials, we expect that hybridization of embossed optical glass waveguide gratings and InP substrates will inevitably lead to new applications in integrated optics. We present our preliminary results of research toward the development of solgel-derived glass waveguide gratings made by embossing on InP. Theoretically, the dependence of the stop-band FWHM and transmission contrast of the grating filter on the grating length, and the relationship between the Bragg grating's reflective wavelength and the dopant concentration in the solgel waveguide, are obtained. Experimentally, using organically modified silane, we solve the problem of mismatching of SiO(2) and InP, and successfully fabricate an embossed glass grating with a second-order Bragg reflection wavelength of 1580 nm and a FWHM of 0.7 nm fabricated upon a solgel waveguide on an InP substrate. PMID:18350088

  16. Coupled-modetheory for magneto-optical fiber Bragg grating under non-uniform magnetic field

    Institute of Scientific and Technical Information of China (English)

    LIU Fen; WU Bao-jian; LU Xin

    2011-01-01

    According to the perturbation theory,the coupled-mode equations for guided optical waves in the magneto-optical fiber Bragg gratings(MFBGs) under non-uniform magnetic field are derived.The equivalent relation between the magneticallyinduced non-uniform fiber Bragg grating(MnFBG) and the corresponding non-magnetic chirped grating is expressed and verified by the piecewise-uniform MFBG model under linear magnetic field.On the basis of the equivalent relation,the MnFBGs can be effectively investigated by means of simulations.The characteristics of the MnFBGs under three typical magnetic field distributions with application to optical pulse compression are simulated,and the minimal pulse width can be achieved for the same magneto-optical coupling parameter of 2.2 × 103 m-1.

  17. Damage evaluation and analysis of composite pressure vessels using fiber Bragg gratings to determine structural health

    Science.gov (United States)

    Ortyl, Nicholas E.

    2005-11-01

    The application of MEMS and nanotechnology (MNT) to the field of structural health monitoring (SHM) is a fairly recent development. The recent change in this focus for MNT has been driven by the need to expand the applications for much of the technologies that were developed in the late 1990s. In addition, many companies desire to expand beyond their target high volume market segments of automotive, wireless communications, and computer peripherals, since these market segments were not as lucrative as first predicted. Most of the aerospace structural health monitoring developmental activity has been sponsored by agencies of the U.S. Government, which serves to pace the examination of these newer technologies to some degree. With that said, efforts are underway by companies such as Acellent Technologies and Blue Road Research to explore various MNT structural health monitoring approaches. The MNT under test include embedded piezoelectric sensors, MEMS accelerometers, time domain region sensors, and topical and embedded single and multi-axis fiber optic Bragg grating sensors. The promise of MNT for the SHM market segment is very enticing. The many wireless communication developments and miniaturization developments of the past five years is very attractive to the SHM community, especially those that are able to reduce the cost and complexity of integration. The main challenge for the community is one of selective integration. That is, certain pieces may be appropriate for SHM systems and certain pieces may not be. The better companies will chose wisely and put forth an approach that can be seamlessly integrated into the larger structure. For over a decade, Blue Road Research has been developing technologies aimed at structural health monitoring of both composite and non-composite parts, through the use of single and multiaxis fiber optic Bragg grating sensors. These sensors are 80 to 120 microns in diameter making them smaller than the diameter of a human hair

  18. Single-pulse coherent anti-Stokes Raman spectroscopy via fiber Bragg grating

    Science.gov (United States)

    Oh, Seung Ryeol; Park, Joo Hyun; Kwon, Won Sik; Kim, Jin Hwan; Kim, Kyung-Soo; Lee, Jae Yong; Kim, Soohyun

    2016-03-01

    Fiber Bragg grating is used in a variety of applications. In this study, we suggest compact, cost-effective coherent anti- Stokes Raman spectroscopy which is based on the pulse shaping methods via commercialized fiber Bragg grating. The experiment is performed incorporating a commercialized femtosecond pulse laser system (MICRA, Coherent) with a 100 mm length of 780-HP fiber which is inscribed 50 mm of Bragg grating. The pump laser for coherent anti-Stokes Raman spectroscopy has a bandwidth of 90 nm and central wavelength of 815 nm with a notch shaped at 785 nm. The positive chirped pulse is compensated by chirped mirror set. We compensate almost 14000 fs2 of positive group delay dispersion for the transform-limited pulse at the sample position. The pulse duration was 15 fs with average power of 50 mW, and showed an adequate notch shape. Finally, coherent anti-Stokes Raman signals are observed using a spectrometer (Jobin Yvon Triax320 and TE-cooled Andor Newton EMCCD). We obtained coherent anti-Stokes Raman signal of acetone sample which have Raman peak at the spectral finger-print region. In conclusion, the proposed method is more simple and cost-effective than the methods of previous research which use grating pairs and resonant photonic crystal slab. Furthermore, the proposed method can be used as endoscope application.

  19. Smart textile sensing system for human respiration monitoring based on fiber Bragg grating

    Science.gov (United States)

    Zhang, Cheng; Miao, Chang-yun; Li, Hong-qiang; Song, Hui-chao; Xu, Fan-jie

    2009-07-01

    Magnetic resonance imaging (MRI) has become an indispensable aid to diagnosis and treatment. As the doctor cannot accompany the patient, it is essential that the patient be monitored remotely to avoid the risk of respiration being impaired by anesthetic drugs or upper airway obstruction. A smart wearable textile sensing system is described in this paper. A fiber Bragg grating (FBG) with polymer encapsulation has been woven into an elastic bandage to detect the respiration motion. According to the strain principle of FBG, the breathing rate and intensity can be obtained by measuring the variety of FBG reflected wavelength. In order to eliminate the temperature cross-sensitivity, a FBG temperature sensor has also been woven into the bandage to achieve the temperature compensation computing. Based on the tunable Fabry-Perot filter wavelength demodulated theory, wavelength measuring method and data processing arithmetic have been presented, and the system with ARM microprocessor has been designed to process and display the breathing information. The experiments to the system have proved that the wavelength measuring range is about 40nm, the resolution of wavelength can arrive at 2pm, and the sampling rate is 5Hz.

  20. Response of fiber Bragg gratings bonded on a glass/epoxy laminate subjected to static loadings

    KAUST Repository

    Mulle, Matthieu

    2015-04-22

    Fiber Bragg gratings (FBG) may be used to monitor strain over the surface of a structure as an alternative technology to conventional strain gauges. However, FBG bonding techniques have still not been established to yield satisfactory surface measurements. Here, two adhesives were investigated, one with low viscosity and the other with high viscosity for bonding FBGs on glass/epoxy sandwich skins. First, instrumented elementary specimens were tested under tension. FBG strain results were analyzed together with digital image correlation (DIC) measurements. The influence of the bonding layer on the measured strain and on the integrity of the sensor was investigated by considering different regions of interest. Next, an instrumented structural sandwich beam was tested under four-point bending. FBG rosettes were compared to conventional strain gauge rosettes. The high viscosity adhesive demonstrated behaviors that affected FBG accuracy. Brittleness of the bonding layer and poor interface adhesion were observed using DIC and X-ray tomography. By contrast, the low viscosity adhesive demonstrated satisfactory results. The FBG strain measurements appeared to be consistent with those of DIC. The accuracy is also adequate as the FBGs and the conventional strain gauges had similar results in three directions, under tension and under compression.