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Sample records for superstructure fiber gratings

  1. Using Finite Element and Eigenmode Expansion Methods to Investigate the Periodic and Spectral Characteristic of Superstructure Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Yue-Jing He

    2016-02-01

    Full Text Available In this study, a numerical simulation method was employed to investigate and analyze superstructure fiber Bragg gratings (SFBGs with five duty cycles (50%, 33.33%, 14.28%, 12.5%, and 10%. This study focuses on demonstrating the relevance between design period and spectral characteristics of SFBGs (in the form of graphics for SFBGs of all duty cycles. Compared with complicated and hard-to-learn conventional coupled-mode theory, the result of the present study may assist beginner and expert designers in understanding the basic application aspects, optical characteristics, and design techniques of SFBGs, thereby indirectly lowering the physical concepts and mathematical skills required for entering the design field. To effectively improve the accuracy of overall computational performance and numerical calculations and to shorten the gap between simulation results and actual production, this study integrated a perfectly matched layer (PML, perfectly reflecting boundary (PRB, object meshing method (OMM, and boundary meshing method (BMM into the finite element method (FEM and eigenmode expansion method (EEM. The integrated method enables designers to easily and flexibly design optical fiber communication systems that conform to the specific spectral characteristic by using the simulation data in this paper, which includes bandwidth, number of channels, and band gap size.

  2. Sensored fiber reinforced polymer grate

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Michael P.; Mack, Thomas Kimball

    2017-08-01

    Various technologies described herein pertain to a sensored grate that can be utilized for various security fencing applications. The sensored grate includes a grate framework and an embedded optical fiber. The grate framework is formed of a molded polymer such as, for instance, molded fiber reinforced polymer. Further, the grate framework includes a set of elongated elements, where the elongated elements are spaced to define apertures through the grate framework. The optical fiber is embedded in the elongated elements of the grate framework. Moreover, bending or breaking of one or more of the elongated elements can be detected based on a change in a characteristic of input light provided to the optical fiber compared to output light received from the optical fiber.

  3. Optical Fiber Grating based Sensors

    DEFF Research Database (Denmark)

    Michelsen, Susanne

    2003-01-01

    In this thesis differenct optical fiber gratings are used for sensor purposes. If a fiber with a core concentricity error (CCE) is used, a directional dependent bend sensor can be produced. The CCE direction can be determined by means of diffraction. This makes it possible to produce long......-period gratings in a fiber with a CCE direction parallel or perpendicular to the writing direction. The maximal bending sensitivity is independent on the writing direction, but the detailed bending response is different in the two cases. A temperature and strain sensor, based on a long-period grating and two...

  4. Hollow-core grating fiber

    Science.gov (United States)

    Barillé, R.; Tajalli, P.; Roy, P.; Ahmadi-kandjani, S.; Kucharski, S.; Ortyl, E.

    2012-02-01

    We propose a new type of hollow-core fiber where the propagation is ensured by a photoinduced self-pattern acting as a surface relief grating (SRG). The SRG is written by launching a suitable laser beam with proper polarization in a capillary glass fiber with the inner surface previously coated with an azopolymer thin film. Such a grating acts as a wavelength/angle dependant reflective mirror and enhances the confinement and the propagation of the light.

  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 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.

  7. Biosensing with optical fiber gratings

    Directory of Open Access Journals (Sweden)

    Chiavaioli Francesco

    2017-06-01

    Full Text Available Optical fiber gratings (OFGs, especially long-period gratings (LPGs and etched or tilted fiber Bragg gratings (FBGs, are playing an increasing role in the chemical and biochemical sensing based on the measurement of a surface refractive index (RI change through a label-free configuration. In these devices, the electric field evanescent wave at the fiber/surrounding medium interface changes its optical properties (i.e. intensity and wavelength as a result of the RI variation due to the interaction between a biological recognition layer deposited over the fiber and the analyte under investigation. The use of OFG-based technology platforms takes the advantages of optical fiber peculiarities, which are hardly offered by the other sensing systems, such as compactness, lightness, high compatibility with optoelectronic devices (both sources and detectors, and multiplexing and remote measurement capability as the signal is spectrally modulated. During the last decade, the growing request in practical applications pushed the technology behind the OFG-based sensors over its limits by means of the deposition of thin film overlays, nanocoatings, and nanostructures, in general. Here, we review efforts toward utilizing these nanomaterials as coatings for high-performance and low-detection limit devices. Moreover, we review the recent development in OFG-based biosensing and identify some of the key challenges for practical applications. While high-performance metrics are starting to be achieved experimentally, there are still open questions pertaining to an effective and reliable detection of small molecules, possibly up to single molecule, sensing in vivo and multi-target detection using OFG-based technology platforms.

  8. Extended and quasi-continuous tuning of quantum cascade lasers using superstructure gratings and integrated heaters

    Energy Technology Data Exchange (ETDEWEB)

    Bidaux, Yves, E-mail: yves.bidaux@alpeslasers.ch [Alpes Lasers SA, 1-3 Passsage Max Meuron, CH-2001 Neuchâtel (Switzerland); Institute for Quantum Electronics, ETH-Zurich, CH-8093 Zurich (Switzerland); Bismuto, Alfredo, E-mail: alfredo.bismuto@alpeslasers.ch; Tardy, Camille; Terazzi, Romain; Gresch, Tobias; Blaser, Stéphane; Muller, Antoine [Alpes Lasers SA, 1-3 Passsage Max Meuron, CH-2001 Neuchâtel (Switzerland); Faist, Jerome [Institute for Quantum Electronics, ETH-Zurich, CH-8093 Zurich (Switzerland)

    2015-11-30

    In this work, we demonstrate broad electrical tuning of quantum cascade lasers at 9.25 μm, 8.5 μm, and 4.4 μm in continuous wave operation using Vernier-effect distributed Bragg reflectors based on superstructure gratings. Integrated micro-heaters allow to switch from one Vernier channel to the other, while predictable and mode-hop free tuning can be obtained in each channel modulating the laser current with a side mode suppression ratio as high as 30 dB. The resulting device behaves effectively as a switchable multicolour tunable source. Tuning up to 6.5% of the central wavelength is observed. To prove the importance of the developed devices for high resolution molecular spectroscopy, a N{sub 2}O absorption spectrum has been measured.

  9. 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.

  10. Cross-fiber Bragg grating transducer

    Science.gov (United States)

    Albin, Sacharia (Inventor); Zheng, Jianli (Inventor); Lavarias, Arnel (Inventor)

    2000-01-01

    A transducer has been invented that uses specially-oriented gratings in waveguide a manner that allows the simultaneous measurement of physical phenomena (such as shear force, strain and temperature) in a single sensing element. The invention has a highly sensitive, linear response and also has directional sensitivity with regard to strain. The transducer has a waveguide with a longitudinal axis as well as two Bragg gratings. The transducer has a first Bragg grating associated with the waveguide that has an angular orientation .theta..sub.a relative to a perpendicular to the longitudinal axis such that 0.degree.<.theta..sub.a <.theta..sub.max. The second Bragg grating is associated with the waveguide in such a way that the angular orientation .theta..sub.b of the grating relative to a perpendicular to the longitudinal axis is (360.degree.-.theta..sub.max)<.theta..sub.b <360.degree.. The first Bragg grating can have a periodicity .LAMBDA..sub.a and the second Bragg grating can have a periodicity .LAMBDA..sub.b such that the periodicity .LAMBDA..sub.a of the first Bragg grating does not equal the periodicity .LAMBDA..sub.b of the second Bragg grating. The angle of the gratings can be such that .theta..sub.a =360.degree.-.theta..sub.b. The waveguide can assume a variety of configurations, including an optical fiber, a rectangular waveguide and a planar waveguide. The waveguide can be fabricated of a variety of materials, including silica and polymer material.

  11. Long period fiber gratings induced by mechanical resonance

    CERN Document Server

    Shahal, Shir; Duadi, Hamootal; Fridman, Moti

    2015-01-01

    We present a simple, and robust method for writing long period fiber gratings with low polarization dependent losses. Our method is based on utilizing mechanical vibrations of the tapered fiber while pooling it. Our method enables real-time tunability of the periodicity, efficiency and length of the grating. We also demonstrate complex grating by writing multiple gratings simultaneously. Finally, we utilized the formation of the gratings in different fiber diameters to investigate the Young's modulus of the fiber.

  12. 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.

  13. Novel algorithm for synthesis of fiber gratings

    Institute of Scientific and Technical Information of China (English)

    Bo LV; Ming CHEN; Dan LU; Taorong GONG; Tangjun LI; Shuisheng JIAN

    2009-01-01

    A novel algorithm for the synthesis of fiber gratings is presented.For the first time we propose an effective optimal approach to construct a coupling coefficient function by employing 4th-order Runge-Kutta (R-K) analysis method for calculating the reflection spectra of fiber gratings.The numerical results show that with this proposed method, some required optical filters have been yielded with better features compared with other methods such as Gel'Fand-Levitan-Marchenko (GLM) algorithm.In addition, the performance of different interpolation functions particularly utilized in our algorithm, including linear-type, spline-type, and Hermit-type, are discussed in detail.

  14. Arc-Induced Long Period Fiber Gratings

    Directory of Open Access Journals (Sweden)

    Gaspar Rego

    2016-01-01

    Full Text Available Long period fiber gratings produced by the electric arc technique have found an increasing interest by the scientific community due to their ease to fabricate, virtually enabling the inscription in any kind of fiber, low cost, and flexibility. In 2005 we have presented the first review on this subject. Since then, important achievements have been reached such as the identification of the mechanisms responsible for gratings formation, the type of symmetry, the conditions to increase fabrication reproducibility, and their inscription in the turning points with grating periods below 200 μm. Several interesting applications in the sensing area, including those sensors working in reflection, have been demonstrated and others are expected, namely, related to the monitoring of extreme temperatures, cryogenic and high temperatures, and high sensitivity refractometric sensors resulting from combining arc-induced gratings in the turning points and the deposition of thin films in the transition region. Therefore, due to its pertinence, in this paper we review the main achievements obtained concerning arc-induced long period fiber gratings, with special focus on the past ten years.

  15. Fiber-bragg grating-loop ringdown method and apparatus

    Science.gov (United States)

    Wang, Chuji

    2008-01-29

    A device comprising a fiber grating loop ringdown (FGLRD) system of analysis is disclosed. A fiber Bragg grating (FBG) or Long-Period grating (LPG) written in a section of single mode fused silica fiber is incorporated into a fiber loop. By utilizing the wing areas of the gratings' bandwidth as a wavelength dependent attenuator of the light transmission, a fiber grating loop ringdown concept is formed. One aspect of the present invention is temperature sensing, which has been demonstrated using the disclosed device. Temperature measurements in the areas of accuracy, stability, high temperature, and dynamic range are also described.

  16. POINT-BY-POINT INSCRIPTION OF FIBER BRAGG GRATINGS INTO BIREFRINGENT OPTICAL FIBER THROUGH PROTECTIVE ACRYLATE COATING BY TI:SA FEMTOSECOND LASER

    Directory of Open Access Journals (Sweden)

    S. V. Arkhipov,

    2016-05-01

    Full Text Available The paper deals withpoint-by-point inscriptionof fiber Bragg gratings by the 800 nm Ti:Sa femtosecond laser pulses into a unique birefringent fiber with elliptical stress cladding of home manufacture. The proposed inscriptionmethod has advantages over the conventional phase mask method. The possibility to create complex grating structures and relatively high transparency of acrylate coating to the Ti:Sa femtosecond laser radiation of 800 nm gives the possibility for inscriptionof phase shifting gratings, chirped grating and superstructures without stripping the fiber. Also, this method makes it possible to inscribethese diffractive structures with and without co-doping of GeO2 in the fiber core. Achieved reflectance was 10%. The microscopic image of the diffractive structure in the fiber core is presented. The grating of 1.07 µm is realized by pulling the fiber with constant speed while the laser pulses are applied with a repetition frequency of 1 kHz. The results are usable in the sphere of creation of different fiber optic sensitive elements based on Bragg gratings.

  17. 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.

  18. 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.

  19. Widely Tunable Monolithic Mid-Infrared Quantum Cascade Lasers Using Super-Structure Grating Reflectors

    OpenAIRE

    Dingkai Guo; Jiun-Yun Li; Liwei Cheng; Xing Chen; Terry Worchesky; Fow-Sen Choa

    2016-01-01

    A monolithic, three-section, and widely tunable mid-infrared (mid-IR) quantum cascade laser (QCL) is demonstrated. This electrically tuned laser consists of a gain section placed between two super structure grating (SSG) distributed Bragg reflectors (DBRs). By varying the injection currents to the two grating sections of this device, its emission wavelength can be tuned from 4.58 μm to 4.77 μm (90 cm−1) with a supermode spacing of 30 nm. This type of SSG-DBR QCLs can be a compact replacement ...

  20. 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.

  1. Fiber optic hot-wire flowmeter based on a metallic coated hybrid long period grating/fiber Bragg grating structure.

    Science.gov (United States)

    Caldas, Paulo; Jorge, Pedro A S; Rego, Gaspar; Frazão, Orlando; Santos, José Luís; Ferreira, Luís Alberto; Araújo, Francisco

    2011-06-10

    In this work an all-optical hot-wire flowmeter based on a silver coated fiber combining a long period grating and a fiber Bragg grating (FBG) structure is proposed. Light from a pump laser at 1480  nm propagating down the fiber is coupled by the long period grating into the fiber cladding and is absorbed by the silver coating deposited on the fiber surface over the Bragg grating structure. This absorption acts like a hot wire raising the fiber temperature locally, which is effectively detected by the FBG resonance shift. The temperature increase depends on the flow speed of the surrounding air, which has the effect of cooling the fiber. It is demonstrated that the Bragg wavelength shift can be related to the flow speed. A flow speed resolution of 0.08  m/s is achieved using this new configuration.

  2. Fiber optical Bragg grating sensors embedded in CFRP wires

    Science.gov (United States)

    Nellen, Philipp M.; Frank, Andreas; Broennimann, Rolf; Meier, Urs; Sennhauser, Urs J.

    1999-05-01

    Based on the example application of Emmenbridge, a newly built steel-concrete-composite bridge in Switzerland with 47 m long built-in carbon fiber reinforced polymer (CFRP) prestressing cables, we will present and analyze the process chain leading to a reliable surveillance of modern civil engineering structures with embedded fiber optical Bragg gratings. This consists first in the embedding of optical fibers and in-fiber Bragg gratings in long CFRP wires in an industrial environment, including fiber optical monitoring of the curing process. Then, various qualifying tests were done: annealing experiments for determining optical lifetime of the Bragg gratings used, dynamic and static tensile tests for estimating their mechanical lifetime under operation, push-out experiments to check adhesion of fiber/coating/matrix interfaces, and performance tests to determine strain and temperature sensitivity of the embedded Bragg gratings. Finally, the prestressing cables were equipped with the CFRP sensor wires and built into the bridge.

  3. Improved layer peeling algorithm for strongly reflecting fiber gratings

    Institute of Scientific and Technical Information of China (English)

    Liqun Huang; Weiping Huang; Jinkuan Wang; Guang Yang

    2006-01-01

    @@ An improved algorithm based on the layer peeling (LP) method is proposed and demonstrated.The new method is shown to be effective for mitigating the impact of numerical errors on reconstruction of coupling function for strongly reflecting Bragg gratings.As examples,a flat-top dispersion-free fiber grating and a fiber-grating dispersion compensator are designed by the improved LP method.For a chirp grating,more accurate results are demonstrated in comparison with those obtained by the integral layer peeling (ILP) method.

  4. Widely Tunable Monolithic Mid-Infrared Quantum Cascade Lasers Using Super-Structure Grating Reflectors

    Directory of Open Access Journals (Sweden)

    Dingkai Guo

    2016-05-01

    Full Text Available A monolithic, three-section, and widely tunable mid-infrared (mid-IR quantum cascade laser (QCL is demonstrated. This electrically tuned laser consists of a gain section placed between two super structure grating (SSG distributed Bragg reflectors (DBRs. By varying the injection currents to the two grating sections of this device, its emission wavelength can be tuned from 4.58 μm to 4.77 μm (90 cm−1 with a supermode spacing of 30 nm. This type of SSG-DBR QCLs can be a compact replacement for the external cavity QCL. It has great potential to achieve gap-free and even further tuning ranges for sensor applications.

  5. Optical Fiber Bragg Grating Michelson Interferometer

    Institute of Scientific and Technical Information of China (English)

    JIANG Yi; JIANG Tian-fu; LIU Li

    2006-01-01

    A new Michelson interferometer based on fiber Bragg grating(FBG) is demonstrated. FBGs are used as reflectors, and the laser is replaced by a broadband source as input light in this interferometer. To demodulate the signals, a 3×3 coupler is used as a splitter. By combining with software demodulation, the outer inter ference can be obtained from the outputs of the interferometer. This kind of in terferometer can also be wavelength-multiplexed easily by composing a series Michelson interferometer. The experiment results show that the clear interference fringe can be obtained by adjusting the path difference to make it less than interference length of FBG. The signals are also demodulated.

  6. 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 s...... 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)......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...

  7. Review of High-Speed Fiber Optic Grating Sensors Systems

    Energy Technology Data Exchange (ETDEWEB)

    Udd, E; Benterou, J; May, C; Mihailov, S J; Lu, P

    2010-03-24

    Fiber grating sensors can be used to support a wide variety of high speed measurement applications. This includes measurements of vibrations on bridges, traffic monitoring on freeways, ultrasonic detection to support non-destructive tests on metal plates and providing details of detonation events. This paper provides a brief overview of some of the techniques that have been used to support high speed measurements using fiber grating sensors over frequency ranges from 10s of kHz, to MHZ and finally toward frequencies approaching the GHz regime. Very early in the development of fiber grating sensor systems it was realized that a high speed fiber grating sensor system could be realized by placing an optical filter that might be a fiber grating in front of a detector so that spectral changes in the reflection from a fiber grating were amplitude modulated. In principal the only limitation on this type of system involved the speed of the output detector which with the development of high speed communication links moved from the regime of 10s of MHz toward 10s of GHz. The earliest deployed systems involved civil structures including measurements of the strain fields on composite utility poles and missile bodies during break tests, bridges and freeways. This was followed by a series of developments that included high speed fiber grating sensors to support nondestructive testing via ultrasonic wave detection, high speed machining and monitoring ship hulls. Each of these applications involved monitoring mechanical motion of structures and thus interest was in speeds up to a few 10s of MHz. Most recently there has been interest in using fiber grating to monitor the very high speed events such as detonations and this has led to utilization of fiber gratings that are consumed during an event that may require detection speeds of hundreds of MHz and in the future multiple GHz.

  8. Fabrication and characterization of sandwiched optical fibers with periodic gratings.

    Science.gov (United States)

    Chiang, Chia-Chin

    2010-08-01

    This study proposes a novel process for fabricating a sandwiched long-period fiber grating (SLPFG) using a SU-8 thick photoresist technique. The SLPFG consists of a thin cladding optical fiber sandwiched with a double-sided periodical grating coating. By varying the external loads on the SLPFG, the transmission dip of the resonance wavelength is tuned according to a squared-harmonic curve. The SLPFG can thus be utilized as a loss tunable filter or sensor. The resonance dip wavelength is related to the cladding thicknesses of the optical fiber and the periods of the grating. A maximum transmission resonant dip of 34.61dB was achieved.

  9. Refractometric sensors based on long period optical fiber gratings

    OpenAIRE

    2006-01-01

    In this work, results of the design of uniform and nonuniform longperiod gratings are presented, with a view to being used as refractometric sensors. We found an optimal combination of the longitudinal variation of the fiber refractive index and the grating period, which increases the sensor linearity in comparison with a uniform grating, without decreasing its average sensitivity within a range of the external refractive index from 1.41 to 1.44.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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...

  16. 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.

  17. 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.

  18. Coupling between counterpropagating cladding modes in fiber Bragg gratings.

    Science.gov (United States)

    Sáez-Rodriguez, D; Cruz, J L; Díez, A; Andrés, M V

    2011-04-15

    We present an experimental demonstration of energy transfer between counterpropagating cladding modes in a fiber Bragg grating (FBG). A strong FBG written in a standard photosensitive optical fiber is illuminated with a single cladding mode, and the power transferred between the forward propagating cladding mode and different backward propagating cladding modes is measured by using two auxiliary long period gratings. Resonances between cladding modes having 30 pm bandwidth and 8 dB rejection have been observed.

  19. Bragg Fibers with Soliton-like Grating Profiles

    Directory of Open Access Journals (Sweden)

    Bugaychuk S.

    2016-01-01

    Full Text Available Nonlinear dynamical system corresponding to the optical holography in a nonlocal nonlinear medium with dissipation contains stable localized spatio-temporal states, namely the grid dissipative solitons. These solitons display a non-uniform profile of the grating amplitude, which has the form of the dark soliton in the reflection geometry. The transformation of the grating amplitude gives rise many new atypical effects for the beams diffracted on such grating, and they are very suitable for the fiber Brass gratings. The damped nonlinear Schrodinger equation is derived that describes the properties of the grid dissipative soliton.

  20. Fiber-guided modes conversion using superposed helical gratings

    Science.gov (United States)

    Ma, Yancheng; Fang, Liang; Wu, Guoan

    2017-03-01

    Optical fibers can support various modal forms, including vector modes, linear polarization (LP) modes, and orbital angular momentum (OAM) modes, etc. The modal correlation among these modes is investigated via Jones matrix, associated with polarization and helical phase corresponding to spin angular momentum (SAM) and OAM of light, respectively. We can generate different modal forms by adopting superposed helical gratings (SHGs) with opposite helix orientations. Detailed analysis and discussion on mode conversion is given as for mode coupling in optical fibers with both low and high contrast index, respectively. Our study may deepen the understanding for various fiber-guided modes and mode conversion among them via fiber gratings.

  1. Single and Multiple Phase Shifts Tilted Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Christophe Caucheteur

    2009-01-01

    Full Text Available The spectral behavior of single and multiple phase shifts tilted fiber Bragg gratings has been experimentally investigated. To this aim, a simple and cost-effective postprocessing technique based on local thermal treatment was used to create arbitrary phase shifts along the tilted grating structure. In particular, UV written tilted fiber Bragg gratings were treated by the electric arc discharge to erase the refractive index modulation in well-defined regions. We demonstrate that these defects give rise to interference pattern for all modes, and thus defect states can be achieved within all the attenuation bands, enabling a simple wavelength independent spectral tailoring of this class of devices.

  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. Analysis of dispersion characteristics of long period fiber grating

    Science.gov (United States)

    Jain, Vishal; Pawar, Santosh; Kumbhaj, S.; Sen, P. K.

    2016-10-01

    Present work deals with theoretical analysis of dispersion characteristics of long period fiber grating using straight forward coupled mode theory. Simple analytical solutions are obtained for co propagating core and cladding modes under linear regime. These solutions are used to derive expressions for transmission coefficient (tLPG), phase (ϕL), delay (τρ) and group velocity dispersion (Dρ) for proposed grating structure. Attention is paid to study the delay response of the grating, by varrying physical parameters like incident wavelength and coupling strength of grating. Negative values of group delay for certain value of coupling strength shows that long period fiber can be used as dispersion compansator device in optical fiber communication link.

  4. Photonic crystal fiber long-period gratings for biochemical sensing.

    Science.gov (United States)

    Rindorf, Lars; Jensen, Jesper B; Dufva, Martin; Pedersen, Lars Hagsholm; Høiby, Poul Erik; Bang, Ole

    2006-09-04

    We present experimental results showing that long-period gratings in photonic crystal fibers can be used as sensitive biochemical sensors. A layer of biomolecules was immobilized on the sides of the holes of the photonic crystal fiber and by observing the shift in the resonant wavelength of a long-period grating it was possible to measure the thickness of the layer. The long-period gratings were inscribed in a large-mode area silica photonic crystal fiber with a CO2 laser. The thicknesses of a monolayer of poly-L-lysine and double-stranded DNA was measured using the device. We find that the grating has a sensitivity of approximately 1.4nm/1nm in terms of the shift in resonance wavelength in nm per nm thickness of biomolecule layer.

  5. Laser Trimming for Adjustment of Grating Offset in Phase-Shifted Fiber Grating Coupler for All-Optical Switching Application

    Institute of Scientific and Technical Information of China (English)

    Hirohisa; Yokota; Yutaka; Sasaki

    2003-01-01

    We theoretically investigated laser trimming to adjust grating offset in phase-shifted fiber grating coupler (FGC) for all-optical switching application. It was clarified that the trimming made the extinction ratio higher in all-optical FGC switch.

  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. 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. 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.

  9. [Composition, physico-chemical properties and molecular superstructure of dietary fiber preparations of the cellan type].

    Science.gov (United States)

    Dongowski, G; Frigge, K; Zenke, I

    1995-07-01

    Dietary fiber preparations of "cellan" type were prepared from apples, white cabbage, sugar beet pulp, soy hulls and wheat bran by treatment with amylolytic and proteolytic enzymes as well as by chemical extractions. Scanning electron microscopic examinations show different morphological structures of the preparations and a high maintenance of native biomolecular superstructure. The content of pectin, protein, polysaccharide-hexoses and -pentoses and the composition of monosaccharides (also after their treatment with 4 or 8% sodium hydroxide) were determined. The cellans possess waterbinding capacities (WBC) between 25 g H2O/g and waterholding capacities between 50 g H2O/g. The WBC is related to the internal surface; it diminishes after treatment with NaOH. The interactions between the cellans and the adsorbed water were characterized by NMR-spin-lattice relaxation time T1. The molecular mobility increases as the water content grows. The T1-values of dried cellans decreased with increasing degree of moisture before drying. The supermolecular structure is comparatively disordered. Only in case of soy cellan a crystalline cellulose-I-modification could be identified by X-ray-diffraction pattern, esp. after NaOH treatment. The low degree of order of cellans was observed in the 13C-NMR spectra, too. Only the soy hull preparation resulted in a spectrum corresponding to well-ordered cellulose. The botanic source has an essential influence on the physico-chemical properties of dietary fiber preparations of cellan type.

  10. Tunable chirped fiber Bragg grating embedded in a textile laminated beam for fiber dispersion compensation

    Science.gov (United States)

    Du, Weichong; Liu, W. P.; Du, David G.; Tam, Hwa-Yaw; Tao, Xiaoming; Yu, ChongXiu; Liu, Shong Hao

    1998-06-01

    A simple method is reported for transformation of a uniform fiber grating into a linear chirped grating and realization of independent tuning of grating's linear chirp degree and central wavelength. This method involves embedding a uniform grating into a textile laminated beam and creating an odd- symmetrical linear strain distribution along the grating versus its center with a three-point-bending and stretching setup. The grating's central wavelength and chirp degree can be tuned by adjusting the horizontal stretching range and vertical bending displacement on the beam independently. A simulated experiment for compensating the dispersion of a standard single-mode fiber over 100km for 10Gbit/s signal at 1550nm window is successfully demonstrated using such a tunable chirped grating with 10 cm in length.

  11. Nonlinear pulse propagation in birefringent fiber Bragg gratings.

    Science.gov (United States)

    Pereira, S; Sipe, J

    1998-11-23

    We present two sets of equations to describe nonlinear pulse propagation in a birefringent fiber Bragg grating. The first set uses a coupled-mode formalism to describe light in or near the photonic band gap of the grating. The second set is a pair of coupled nonlinear Schroedinger equations. We use these equations to examine viable switching experiments in the presence of birefringence. We show how the birefringence can both aid and hinder device applications.

  12. Analysis of New Q-switched Erbium Doped Fiber Laser Based on Fiber Grating Loop Mirror

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An all-fiber wavelength selective Q-switching modulator based on fiber grating loop mirror is proposed. A newly configured Q-switched erbium doped fiber laser using this all-fiber modulator is numerically analyzed taking into account the effects of the spontaneous emission.

  13. Photonic crystal fiber long-period gratings for biochemical sensing

    DEFF Research Database (Denmark)

    Rindorf, Lars Henning; Jensen, Jesper Bo; Dufva, Hans Martin

    2006-01-01

    -period grating it was possible to measure the thickness of the layer. The long-period gratings were inscribed in a large-mode area silica photonic crystal fiber with a CO2 laser. The thicknesses of a monolayer of poly-L-lysine and double-stranded DNA was measured using the device. We find that the grating has...... a sensitivity of approximately 1.4nm/1nm in terms of the shift in resonance wavelength in nm per nm thickness of biomolecule layer....

  14. 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.

  15. 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.

  16. Full vector complex coupled mode theory for tilted fiber gratings.

    Science.gov (United States)

    Lu, Yu-Chun; Huang, Wei-Ping; Jian, Shui-Sheng

    2010-01-18

    A full vector complex coupled mode theory (CMT) for the analysis of tilted fiber gratings is presented. With the combination of the perfectly matched layer (PML) and the perfectly reflecting boundary (PRB), the continuous radiation modes are well represented by a set of discrete complex modes. Simulation of coupling to radiation modes is greatly simplified and may be treated in the same fashion as guided modes. Numerical results of the tilted fiber Bragg gratings (TFBGs) with outer-cladding index equal, lower and higher than that of the inner-cladding indicate that the complex coupled mode approach is highly effective in the simulation of couplings to cladding and radiation modes in tilted fiber gratings. The reflective TFBGs are investigated by the proposed approach in detail.

  17. 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.

  18. Bragg grating fiber optic sensing for bridges and other structures

    Science.gov (United States)

    Measures, Raymond M.; Alavie, A. Tino; Maaskant, Robert; Huang, Shang Yuan; LeBlanc, Michel

    1994-09-01

    We have demonstrated that fiber optic intracore Bragg grating sensors are able to measure the strain relief experienced over an extended period of time by both steel and carbon composite tendons within the concrete deck support girders of a recently constructed two span highway bridge. This is the first bridge in the world to test the prospects of using carbon fiber composite tendons to replace steel tendons. This unique set of measurements was accomplished with an array of 15 Bragg grating fiber optic sensors that were embedded within the precast concrete girders during their construction. We have also demonstrated that these same sensors can measure the change in the internal strain within the girders associated with both static and dynamic loading of the bridge with a truck. We are now studying the ability of Bragg grating fiber optic sensors to measure strong strain gradients and thereby provide a warning of debonding of any Bragg grating sensor from its host structure...one of the most important failure modes for any fiber optic strain sensor.

  19. Design of vibration sensor based on fiber Bragg grating

    Science.gov (United States)

    Zhang, Zhengyi; Liu, Chuntong

    2017-06-01

    Fiber grating is a kind of new type of fiber optic light source device which has been rapidly changing in the refractive index of the core in recent years. Especially, it can realize the high precision of the external parameters by means of the special structure design and the encapsulation technology [1, 2]. In this paper, a fiber grating vibration sensor which is suitable for vibration monitoring in key areas is designed based on the technical background of vibration monitoring system. The sensor uses a single beam structure and pastes the fiber Bragg grating (FBG) to measure the vibration wavelength on the surface. When the vibration is simply harmonic vibration, the Bragg reflection wavelength will change periodically, and the periodic variation of the wavelength curve can be measured by the fiber grating demodulator, then the correctness of the experimental results is verified. In this paper, through the analysis of the data measured by the demodulator, the MATLAB software is used to verify the data, and the different frequency domains, the modes, and the phase frequency curves are obtained. The measurement range is 0 Hz-100 Hz, and the natural frequency is 90.6 Hz.

  20. High frequency strain measurements with fiber Bragg grating sensors

    Science.gov (United States)

    Koch, J.; Angelmahr, M.; Schade, W.

    2015-05-01

    In recent years fiber Bragg grating sensors gained interest in structural health monitoring and concepts for smart structures. They are small, lightweight, and immune to electromagnetic interference. Using multiplexing techniques, several sensors can be addressed by a single fiber. Therefore, well-established structures and materials in industrial applications can be easily equipped with fiber optical sensors with marginal influence on their mechanical properties. In return, critical components can be monitored in real-time, leading to reduced maintenance intervals and a great reduction of costs. Beside of generally condition monitoring, the localization of failures in a structure is a desired feature of the condition monitoring system. Detecting the acoustic emission of a sudden event, its place of origin can be determined by analyzing the delay time of distributed sensor signals. To achieve high localization accuracies for the detection of cracks, breaks, and impacts high sampling rates combined with the simultaneous interrogation of several fiber Bragg grating sensors are required. In this article a fiber Bragg grating interrogator for high frequency measurements up to the megahertz range is presented. The interrogator is based on a passive wavelength to intensity conversion applying arrayed waveguide gratings. Light power fluctuations are suppressed by a differential data evaluation, leading to a reduced signal-to-noise ratio and a low strain detection limit. The measurement system is used to detect, inter alia, wire breaks in steel wire ropes for dockside cranes.

  1. Continuously Tunable Erbium-Doped Fiber Ring Laser Using Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    S. W. Harun H. Ahmad and P. Poopalan

    2012-08-01

    Full Text Available An efficient tunable erbium-doped fiber (EDF ring laser utilizing a single fiber Bragg grating (FBG and an optical circulator is investigated. The laser demonstrates a threshold of 3.43 mW and a slope efficiency of 12.5%. Tunability of the fiber laser is obtained by thermal tuning of the FBG. Simultaneous temperature tuning demonstrates a 0.01 nm/oC variation in laser wavelength.Key Words:  Fiber Bragg grating, fiber laser, tunable laser, ring laser, thermal tuning

  2. Round Robin for Optical Fiber Bragg Grating Metrology.

    Science.gov (United States)

    Rose, A H; Wang, C M; Dyer, S D

    2000-01-01

    NIST has administered the first round robin of measurements for optical fiber Bragg gratings. We compared the measurement of center wavelength, bandwidth, isolation, minimum relative transmittance, and relative group delay among several grating types in two industry groups, telecommunications and sensors. We found that the state of fiber Bragg grating metrology needs improvement in most areas. Specifically, when tunable lasers are used a filter is needed to remove broadband emissions from the laser. The linear slope of relative group delay measurements is sensitive to drift and systematic bias in the rf-modulation technique. The center wavelength measurement had a range of about 27 pm in the sensors group and is not adequate to support long-term structural monitoring applications.

  3. 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.

  4. 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.

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

    OpenAIRE

    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 ...

  6. 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 mPOF w......POF with only a 2.5-s writing time....

  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. Slow light in fiber Bragg gratings and its applications

    Science.gov (United States)

    Skolianos, George; Arora, Arushi; Bernier, Martin; Digonnet, Michel

    2016-11-01

    Slow-light fiber Bragg gratings (FBGs) belong to a class of gratings designed to exhibit one or more narrow resonances in their reflection and transmission spectra, produced either by introducing a π phase shift near the middle of the grating, or by increasing the index modulation so that the grating behaves like a Fabry-Perot interferometer. These resonances can have very narrow linewidths (optics, optical switching, optical delay lines, and sensing. This paper reviews the principle of these gratings, in particular the more recent slow-light gratings relying on a strong index modulation. It discusses in particular the requirements for achieving large group delays and high sensitivities in sensors, and the fabrication and annealing techniques used to meet these requirements (high index modulation, low loss, index-profile apodization, and optimized length). Several applications are presented, including record-breaking FBGs that exhibit a group delay of 42 ns and Q-factor of ~30 million over a 12.5 mm length, robust acoustic sensors with pressure resolution of ~50 µPa (√Hz)-1 in the few-kHz, and a strain sensor capable of resolving as little as 30 femtostrain (√Hz)-1.

  9. Development and Application of Fiber Bragg Grating Clinometer

    Science.gov (United States)

    Guo, Xin; Li, Wen; Wang, Wentao; Feng, Xiaoyu

    2017-06-01

    Using FBG (fiber bragg grating) technology in clinometers can solve the technological problem facing by wireless transmission devices like big data transfer volume and poor stability, which has been receiving more and more attention. This paper discusses a new clinometer that is designed and transformed based on upgrading current clinometers, installing fiber grating strain gauges and fiber thermometers, and carrying out studies on such aspects as equipment upgrading, on-site setting, and data acquisition and analysis. In addition, it brings up the method of calculating displacement change based on wavelength change; this method is used in safety monitoring of the right side slope of Longyong Expressway ZK56+860 ~ ZK56+940 Section. Data shows that the device is operating well with a higher accuracy, and the slope is currently in a steady state. The equipment improvement and the method together provide reference data for safety analysis of the side slope.

  10. Optical Fiber Grating Sensor for Force Measurement of Anchor Cable

    Institute of Scientific and Technical Information of China (English)

    JIANG Desheng; FU Jinghua; LIU Shengchun; SUI Lingfeng; FU Rong

    2006-01-01

    The development of the sensor suitable for measuring large load stress to the anchor cable becomes an important task in bridge construction and maintenance. Therefore, a new type of optical fiber sensor was developed in the laboratory - optical fiber grating sensor for force measurement of anchor cable (OFBFMAC). No similar report about this kind of sensor has been found up to now in China and other countries. This sensor is proved to be an effective way of monitoring in processes of anchor cable installation, cable cutting, cable force regulation, etc, with the accurate and repeatable measuring results. Its successful application in the tie bar cable force safety monitoring for Wuhan Qingchuan bridge is a new exploration of optical fiber grating sensing technology in bridge tie bar monitoring system.

  11. 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.

  12. Stratified waveguide grating coupler for normal fiber incidence.

    Science.gov (United States)

    Wang, Bin; Jiang, Jianhua; Chambers, Diana M; Cai, Jingbo; Nordin, Gregory P

    2005-04-15

    We propose a new stratified waveguide grating coupler (SWGC) to couple light from a fiber at normal incidence into a planar waveguide. SWGCs are designed to operate in the strong coupling regime without intermediate optics between the fiber and the waveguide. Two-dimensional finite-difference time-domain simulation in conjunction with microgenetic algorithm optimization shows that approximately 72% coupling efficiency is possible for fiber (core size of 8.3 microm and delta=0.36%) to slab waveguide (1.2-microm core and delta=3.1%) coupling. We show that the phase-matching and Bragg conditions are simultaneously satisfied through the fundamental leaky mode.

  13. Low-cost and biocompatible long-period fiber gratings

    Science.gov (United States)

    Soto-Olmos, Jorge A.; Oropeza-Ramos, Laura; Hernández-Cordero, Juan

    2011-09-01

    In this paper, a low-cost long-period fiber grating (LPFG) induced by a polymeric microstructure is demonstrated. LPFGs are induced on a tapered optical fiber (TOF) when a periodic micro-grating comes into contact with the thin region of the fiber. The micro-grating device is made using polydimethylsiloxane (PDMS), an inexpensive, nontoxic and optically transparent polymer that is extensively used in microfluidics, organic electronics and biotechnological applications. Soft lithography, along with molds built from thermoplastic polystyrene sheets, makes the fabrication straightforward and extremely low-cost. Additionally, no precision machining is necessary and the resolution of the microstructures is limited only by the resolution of the laser printer used for patterning the polystyrene sheets. The TOF and the micro-grating were dimensionally characterized using optical microscopy and white light interferometry, respectively. Variations on the optical spectrum due to pressure and temperature were observed and their magnitudes were similar to those obtained using metallic microstructures. Thus, LPFGs can be made in an inexpensive and expeditious way using PDMS and TOFs. These polymeric devices can be integrated into microfluidic and other labon- a-chip systems where biocompatibility is a valuable characteristic.

  14. Carbon nanotube coated fiber Bragg grating for photomechanical optic modulator.

    Science.gov (United States)

    Shivananju, B N; Suri, Ashish; Asokan, Sundarrajan; Misra, Abha

    2013-09-01

    We have demonstrated novel concept of utilizing the photomechanical actuation in carbon nanotubes (CNTs) to tune and reversibly switch the Bragg wavelength. When fiber Bragg grating coated with CNTs (CNT-FBG) is exposed externally to a wide range of optical wavelengths, e.g., ultraviolet to infrared (0.2-200 μm), a strain is induced in the CNTs which alters the grating pitch and refractive index in the CNT-FBG system resulting in a shift in the Bragg wavelength. This novel approach will find applications in telecommunication, sensors and actuators, and also for real time monitoring of the photomechanical actuation in nanoscale materials.

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

    DEFF Research Database (Denmark)

    Stefani, Alessio

    and gluing of polymer to silica fibers are discussed. The realization of gratings in polymer fibers is shown with two different techniques: the UV phase mask technique and the direct writing technique reported here for the first time for polymer fibers. Realization of gratings in PMMA step index fibers...

  17. Characteristics of a Tunable Microwave Photonics Notch Filter Based on Two Fiber Bragg Gratings

    Institute of Scientific and Technical Information of China (English)

    YUXianbin; ZHANGXianmin; CHIHao; CHENKangsheng

    2005-01-01

    We investigate theoretically the characteristic of a tunable microwave fiber-optic notch flter based on two fiber gratings. The microwave frequency response based on the refiectivities of two fiber gratings is analyzed and the optimum filter condition is obtained. The refiectivity of the first fiber grating can be tuned experimentally by adjusting the wavelength of input light. Experimental results are in agreement with the theory. The largest notch depth is more than 15dB. The free-spectral range can be tuned by altering the length of fiber between two fiber gratings.

  18. New multiplexing scheme for monitoring fiber optic Bragg grating sensors in the coherence domain

    OpenAIRE

    Dakin, J.P.; Ecke, W.; Rothardt, M.; Schauer, J; Usbeck, K.; Willsch, R.

    1997-01-01

    A new multiplexing scheme for monitoring fiber optic Bragg gratings in the coherence domain has been developed. Grating pairs with different grating distances are distributed along a fiber line, and interference between their reflections is monitored with a scanning Michelson interferometer. The Bragg wavelength of the individual sensor elements is determined from the interference signal frequency

  19. Fabrication and Characterization of Tilted Fiber Optic Bragg Grating Filters over Various Wavelengths

    Science.gov (United States)

    Grant, Joseph; Jackson, Kurt V.; Wang, Y.; Sharma, A.; Burdine, Robert V. (Technical Monitor)

    2002-01-01

    Fiber Optic Bragg Grating taps are fabricated and characterized at various wavelengths using a modified Talbot interferometric technique. Gratings are fabricated by tilting the photosensitive fiber to angles up to 45 degrees w.r.t. the writing angle. Diffraction characteristics of the tilted grating is monitored in first and second orders.

  20. 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...

  1. 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

    and because they allow to tune the guiding parameters by modifying the microstructure. Now a days the only technique used to write gratings in such fibers is the phase mask technique with UV light illumination. Despite the good results that have been obtained, a limited flexibility on the grating design...... 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 gratings make the point-by-point grating writing technique very interesting and would appear to be able to fill this technological gap. On the other end this technique is hardly applicable for microstructured fibers because of the writing beam being scattered by the air-holes. We report on the design...

  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. Narrow Bandwidth 850-nm Fiber Bragg Gratings in Few-Mode Polymer Optical Fibers

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, Wu; Markos, Christos;

    2011-01-01

    We report on the inscription and characterization of narrow bandwidth fiber Bragg gratings (FBGs) with 850-nm resonance wavelength in polymer optical fibers (POFs). We use two fibers: an in-house fabricated microstructured POF (mPOF) with relative hole size of 0.5 and a commercial step-index POF......, which supports six modes at 850 nm. The gratings have been written with the phase-mask technique and a 325-nm HeCd laser. The mPOF grating has a full-width at half-maximum (FWHM) bandwidth of 0.29 nm and the step-index POF has a bandwidth of 0.17 nm. For both fibers, the static tensile strain...

  4. Torsion sensing characteristics of long period fiber gratings fabricated by femtosecond laser in optical fiber

    Science.gov (United States)

    Duan, Ji'an; Xie, Zheng; Wang, Cong; Zhou, Jianying; Li, Haitao; Luo, Zhi; Chu, Dongkai; Sun, Xiaoyan

    2016-09-01

    With the alignment of the fiber core systems containing dual-CCDs and high-precision electric displacement platform, twisted long period fiber gratings (T-LPFGs) were fabricated in two different twisted SMF-28 fibers by femtosecond laser. The torsion characteristics of the T-LPFGs were experimentally and theoretical investigated and demonstrated in this study. The achieved torsion sensitivity is 117.4 pm/(rad/m) in the torsion range -105-0 rad/m with a linearity of 0.9995. Experimental results show that compared with the ordinary long period fiber gratings, the resonance wavelength of the gratings presents an opposite symmetrical shift depending on the twisting direction after the applied torsion is removed. In addition, high sensitivity could be obtained, which is very suitable for the applications in the torsion sensor. These results are important for the design of new torsion sensors based on T-LPFGs fabricated by femtosecond laser.

  5. 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.

  6. 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.

  7. Fiber design and realization of point-by-point written fiber Bragg gratings in polymer optical fibers

    Science.gov (United States)

    Stefani, Alessio; Stecher, Matthias; Town, Graham E.; Bang, Ole

    2012-04-01

    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 because they allow to tune the guiding parameters by modifying the microstructure. Now a days the only technique used to write gratings in such fibers is the phase mask technique with UV light illumination. Despite the good results that have been obtained, a limited flexibility on the grating design 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 gratings make the point-by-point grating writing technique very interesting and would appear to be able to fill this technological gap. On the other end this technique is hardly applicable for microstructured fibers because of the writing beam being scattered by the air-holes. We report on the design and realization of a microstructured polymer optical fiber made of PMMA for direct writing of FBGs. The fiber was designed specifically to avoid obstruction of the writing beam by air-holes. The realized fiber has been used to point-by-point write a 5 mm long fourth order FBG with a Bragg wavelength of 1518 nm. 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 2.5 seconds needed.

  8. Passive Temperature-Compensating Technique for Microstructured Fiber Bragg Gratings

    CERN Document Server

    Huy, Minh Châu Phan; Dewynter, Véronique; Ferdinand, Pierre; Pagnoux, Dominique; Dussardier, Bernard; Blanc, Wilfried; 10.1109/JSEN.2008.926169

    2010-01-01

    The thermal drift of the characteristic wavelength of fiber Bragg gratings (FBGs) photowritten in the core of microstructured fibers (MOFs) is significantly reduced by inserting a liquid of suitable refractive index into their holes. For instance, the spectral range of variations is divided by a factor of 4 over a temperature range larger than 20\\degree C in a six-hole MOF, and the maximum sensitivity is reduced. Such passive FBG temperature compensation technique is of great interest for applications involving accurate sensing free of thermal effects.

  9. 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.

  10. Switchable dual-wavelength erbium-doped fiber laser with a tilted fiber grating

    Institute of Scientific and Technical Information of China (English)

    JIN Long; KAI Gui-yun; XU Ling-ling; LIU Bo; ZHANG Jian; LIU Yan-ge; YUAN Shu-zhong; DONG Xiao-yi

    2007-01-01

    A dual-wavelength erbium doped fiber laser with a tilted fiber Bragg grating and photonic crystal fiber is proposed and demonstrated. In the laser,a 2W EDFA provides gain for all the laser lines; the highly nonlinear photonic crystal fiber introduces dynamic energy transfer between the two wavelengths caused by four wave mixing effect,so that a stable dualwavelength oscillation at room temperature is implemented. Different switching modes can be achieved by adjusting the lateral offset between the fiber grating and the guiding single mode fiber or by varying the state of polarization in the laser cavity. The maximum of output power of the laser has reached 314 mW.

  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. 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.

  13. Fiber-Optic Gratings for Lidar Measurements of Water Vapor

    Science.gov (United States)

    Vann, Leila B.; DeYoung, Russell J.

    2006-01-01

    Narrow-band filters in the form of phase-shifted Fabry-Perot Bragg gratings incorporated into optical fibers are being developed for differential-absorption lidar (DIAL) instruments used to measure concentrations of atmospheric water vapor. The basic idea is to measure the relative amounts of pulsed laser light scattered from the atmosphere at two nearly equal wavelengths, one of which coincides with an absorption spectral peak of water molecules and the other corresponding to no water vapor absorption. As part of the DIAL measurement process, the scattered light is made to pass through a filter on the way to a photodetector. Omitting other details of DIAL for the sake of brevity, what is required of the filter is to provide a stop band that: Surrounds the water-vapor spectral absorption peaks at a wavelength of 946 nm, Has a spectral width of at least a couple of nanometers, Contains a pass band preferably no wider than necessary to accommodate the 946.0003-nm-wavelength water vapor absorption peak [which has 8.47 pm full width at half maximum (FWHM)], and Contains another pass band at the slightly shorter wavelength of 945.9 nm, where there is scattering of light from aerosol particles but no absorption by water molecules. Whereas filters used heretofore in DIAL have had bandwidths of =300 pm, recent progress in the art of fiber-optic Bragg-grating filters has made it feasible to reduce bandwidths to less than or equal to 20 pm and thereby to reduce background noise. Another benefit of substituting fiber-optic Bragg-grating filters for those now in use would be significant reductions in the weights of DIAL instruments. Yet another advantage of fiber-optic Bragg-grating filters is that their transmission spectra can be shifted to longer wavelengths by heating or stretching: hence, it is envisioned that future DIAL instruments would contain devices for fine adjustment of transmission wavelengths through stretching or heating of fiber-optic Bragg-grating filters

  14. 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.

  15. Compensating large PMD by a fiber grating

    Institute of Scientific and Technical Information of China (English)

    Tangjun Li(李唐军); Muguang Wang(王目光); Cao Diao(刁操); Shuisheng Jian(简水生)

    2004-01-01

    In this paper, the first- and second-order polarization mode dispersion (PMD) with the amount of 132.994-ps differential group-delay (DGD) and maximum 476.129-ps/nm second-order PMD can be compensated by a two-stages PMD compensator at a 40-Gb/s optical fiber communication system. The first stage has one free degree that is used for first order and high orders PMD compensations by rotating the state of polarization. The second-stage is used for remainder PMD compensations. After compensation, the average DGD and the maximum second-order PMD are reduced to 345.310 fs and 3.102 ps/nm, respectively.

  16. Interrogating adhesion using fiber Bragg grating sensing technology

    Science.gov (United States)

    Rasberry, Roger D.; Rohr, Garth D.; Miller, William K.; Udd, Eric; Blach, Noah T.; Davis, Ryan A.; Olson, Walter R.; Calkins, David; Roach, Allen R.; Walsh, David S.; McElhanon, James R.

    2015-05-01

    The assurance of the integrity of adhesive bonding at substrate interfaces is paramount to the longevity and sustainability of encapsulated components. Unfortunately, it is often difficult to non-destructively evaluate these materials to determine the adequacy of bonding after manufacturing and then later in service. A particularly difficult problem in this regard is the reliable detection/monitoring of regions of weak bonding that may result from poor adhesion or poor cohesive strength, or degradation in service. One promising and perhaps less explored avenue we have recently begun to investigate for this purpose centers on the use of (chirped) fiber Bragg grating sensing technology. In this scenario, a grating is patterned into a fiber optic such that a (broadband) spectral reflectance is observed. The sensor is highly sensitive to local and uniform changes across the length of the grating. Initial efforts to evaluate this approach for measuring adhesive bonding defects at substrate interfaces are discussed. 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.

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

    Science.gov (United States)

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

    2016-09-11

    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.

  18. Bragg gratings in surface-core fibers: Refractive index and directional curvature sensing

    Science.gov (United States)

    Osório, Jonas H.; Oliveira, Ricardo; Aristilde, Stenio; Chesini, Giancarlo; Franco, Marcos A. R.; Nogueira, Rogério N.; Cordeiro, Cristiano M. B.

    2017-03-01

    In this paper, we report, to our knowledge, the first extended study of the inscription of Bragg gratings in surface-core fibers and their application in refractive index and directional curvature sensing. The research ranges from fiber fabrication and grating inscription in untapered and tapered fibers to the performance of simulations and sensing measurements. Maximum sensitivities of 40 nm/RIU and 202.7 pm/m-1 were attained in refractive index and curvature measurements respectively. The obtained results compares well to other fiber Bragg grating based devices. Ease of fabrication, robustness and versatility makes surface-core fibers an interesting platform when exploring fiber sensing devices.

  19. A Novel Fabrication for Method Long Period Fiber Grating

    Institute of Scientific and Technical Information of China (English)

    HE Shuo; LI Xinwan; YE Ailun; HE Wanxun; SONG Hao

    2002-01-01

    A new method of fabricating all-fiber broadband-rejection filter based on long period fiber grating (LPFG) is proposed. The principle in the method is to make periodic asymmetrical deformation in the core of fiber without microbends by electrode discharging so as to induce periodic refractive index changes. Two kinds of filters whose rejection peak wavelength at 1550 nm and 1310 nm are obtained. The insertion loss is less than 0.6 dB and 1.4 dB respectively. The 20 dB bandwidth ranges from 10 nm to 39 nm. The backward reflection loss is extremely small (less than -70 dB). Such devices can be used as isolation filters in 1310/1550 nm WDM system and other fields.

  20. Multiplexing technique using amplitude-modulated chirped fiber Bragg gratings

    Science.gov (United States)

    Wong, Allan C. L.; Childs, Paul A.; Peng, Gang-Ding

    2007-07-01

    We propose a new multiplexing technique using amplitude-modulated chirped fiber Bragg gratings that have an identical center Bragg wavelength. Each grating is inscribed with a unique amplitude modulation that allows them to be multiplexed with complete overlapping within a certain bandwidth. To demodulate the multiplexed signal, the discrete wavelet transform is employed. Concurrently, a wavelet denoising technique is used to reduce the noise. This proposed multiplexing technique has been verified through strain measurements. Experimental results showed that for strains applied up to 1250 μɛ the absolute error and cross-talk are within ±20 μɛ and 16 μɛ, respectively. A strain resolution of 4 μɛ is obtained.

  1. Recent Progress in Multiparameter Measurement Based on Extrinsic Fiber-Optic Fabry-Perot Interferometers and Fiber Gratings

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    This paper presents a review of recent progress in simultaneous measurement of multiparameters including strain, temperature, vibration, transverse load, based on the combinations of extrinsic fiber-optic Fabry-Perot interferometers and fiber gratings.

  2. 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.

  3. Erbium-doped CW and Q-switched fiber ring laser with fiber grating Michelson interferometer

    Institute of Scientific and Technical Information of China (English)

    Anting Wang(王安廷); Meishu Xing(邢美术); Hai Ming(明海); Jianping Xie(谢建平); Lixin Xu(许立新); Wencai Huang(黄文财); Liang Lü(吕亮); Xiyao Chen(陈曦曜); Feng Li(李锋); Yunxia Wu(吴云霞)

    2003-01-01

    The band-pass characteristic of fiber grating Michelson interferometer is analyzed, which acts as both band-pass filter and Q-switch. An erbium-doped fiber ring laser based on fiber grating Michelson interferometer is implemented for producing single longitudinal mode CW operation with 5 MHz spectral linewidth and up to 6 mW output power. In Q-switched operation, stable fiber laser output pulses with repetition rate of 800 Hz, pulse width of 0.6μs, average power of 1.8 mW and peak power of 3.4 W are demonstrated. The peak power and average power of the Q-switched pulses are varied with the repetition rate.

  4. Erbium-doped CW and Q-switched fiber ring laser with fiber grating Michelson interferometer

    Science.gov (United States)

    Wang, Anting; Ming, Hai; Xie, Jianping; Xu, Lixin; Huang, Wencai; Lv, Liang; Chen, Xiyao; Li, Feng; Wu, Yunxia; Xing, Meishu

    2003-01-01

    The band-pass characteristic of fiber grating Michelson interferometer is analyzed, which acts as both band-pass filter and Q-switch. An erbium-doped fiber ring laser based on fiber grating Michelson interferometer is implemented for producing single longitudinal mode CW operation with 5 MHz spectral linewidth and up to 6 mW output power. In Q-switched operation, stable fiber laser output pulses with repetition rate of 800 Hz, pulse width of 0.6 ?s, average power of 1.8 mW and peak power of 3.4 W are demonstrated. The peak power and average power of the Q-switched pulses are varied with the repetitionrate.

  5. Fiber-optic Doppler velocimeter based on a dual-polarization fiber grating laser

    Science.gov (United States)

    Kuang, Zeyuang; Cheng, Linghao; Liang, Yizhi; Liang, Hao; Guan, Bai-Ou

    2015-07-01

    A fiber-optic Doppler velocimeter based on a dual-polarization fiber grating laser is demonstrated. The fiber grating laser produces two orthogonally polarized laser outputs with their frequency difference proportional to the intra-cavity birefringence. When the laser outputs are reflected from a moving targets, the laser frequencies will be shifted due to the Doppler effect. It shows that the frequency difference between the beat note of the laser outputs and the beat note of the reflected lasers is proportional to the velocity. The proposed fiber-optic Doppler velocimeter shows a high sensitivity of 0.64 MHz/m/s and is capable of measurement of wide range of velocity.

  6. Development of pulse laser processing for mounting fiber Bragg grating

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Aikihko; Shimada, Yukihiro; Yonemoto, Yukihiro; Suzuki, Hirokazu; Ishibashi, Hisayoshi [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7 Umebidai Kidugawa Kyoto 619-0215 (Japan); Applied Laser Technology Institute, Tsuruga Head Office, Japan Atomic Energy Agency, 65-20 Kizaki Tsuruga Fukui 914-8585 (Japan); Technical Research and Development Institute, Kumagai Gumi Co., Ltd., 2-1 Tsukudo, Shinjuku Tokyo 162-8557 (Japan)

    2012-07-11

    Pulse laser processing has been developed for the application of industrial plants in monitoring and maintenance. Surface cleaning by nano-second laser ablation was demonstrated for decontamination of oxide layers of Cr contained steel. Direct writing by femtosecond processing induced a Bragg grating in optical fiber to make it a seismic sensor for structural health monitoring. Adhesive cement was used to fix the seismic sensor on the surface of reactor coolant pipe material. Pulse laser processing and its related technologies were presented to overcome the severe accidents of nuclear power plants.

  7. Development of pulse laser processing for mounting fiber Bragg grating

    Science.gov (United States)

    Nishimura, Aikihko; Shimada, Yukihiro; Yonemoto, Yukihiro; Suzuki, Hirokazu; Ishibashi, Hisayoshi

    2012-07-01

    Pulse laser processing has been developed for the application of industrial plants in monitoring and maintenance. Surface cleaning by nano-second laser ablation was demonstrated for decontamination of oxide layers of Cr contained steel. Direct writing by femtosecond processing induced a Bragg grating in optical fiber to make it a seismic sensor for structural health monitoring. Adhesive cement was used to fix the seismic sensor on the surface of reactor coolant pipe material. Pulse laser processing and its related technologies were presented to overcome the severe accidents of nuclear power plants.

  8. Design of chirped fiber gratings for optical beamforming networks

    Institute of Scientific and Technical Information of China (English)

    YE Ying-bo; SHI Pei-ming; HUANG Shan-guo; ZHOU Jing

    2011-01-01

    The properties of the linear chirped fiber grating (CFG) which is used in the true time delay unit of the optical beamforming networks (OBFNs) are studied intensively through theoretical analyses and numerical calculations.It is concluded that the dispersion of the CFG is equal to 1/(3Gc),where G is the chirp coefficient of CFG and c is the light speed.Based on this relationship,a simplified designing process of a CFG which satisfies the requirements of the OB FN is given.The simulation results are coincident with the theoretical conclusions.

  9. Ag-coated Long-period Fiber Grating

    Institute of Scientific and Technical Information of China (English)

    GU Zheng-tian; XU Yan-ping; CHEN Jia-bi

    2005-01-01

    Based on coupled-mode theory, the eigenvalue equation of five-layered long-period fiber grating (LPFG) sensor with Ag film and gas-sensitive film overlays are firstly studied. The problem of resolving complex eigenvalue equation on five-layered LPFG is analyzed, and the method of resolution is also given.Then the eigenvalue equation of three-layered metal cladding LPFG is analyzed, and the complex transcendental equation is also discussed. The computing result shows that the coupling between the low-order EH modes and the core mode is much stronger than that between the low-order HE modes and the core mode.

  10. Tunable Optical Filter Based on Mechanically Induced Cascaded Long Period Optical Fiber Grating

    Directory of Open Access Journals (Sweden)

    Sunita P. Ugale

    2013-01-01

    Full Text Available We have proposed and demonstrated experimentally a novel and simple tunable optical filter based on mechanically induced and cascaded long period optical fiber gratings. In this filter variable FWHM and center wavelength is provided by cascading long period and ultralong period optical fiber gratings with different periods in a novel fiber structure. We report here for the first time to our knowledge the characterization of mechanically induced long period fiber gratings with periods up to several millimeters in novel multimode-single-mode-multimode fiber structure. We have obtained maximum loss peak of around 20 dB.

  11. Orientation-dependent fiber-optic accelerometer based on grating inscription over fiber cladding.

    Science.gov (United States)

    Rong, Qiangzhou; Qiao, Xueguang; Guo, Tuan; Bao, Weijia; Su, Dan; Yang, Hangzhou

    2014-12-01

    An orientation-sensitive fiber-optic accelerometer based on grating inscription over fiber cladding has been demonstrated. The sensor probe comprises a compact structure in which a short section of thin-core fiber (TCF) stub containing a "cladding" fiber Bragg grating (FBG) is spliced to another single-mode fiber (SMF) without any lateral offset. A femtosecond laser side-illumination technique was utilized to ensure that the grating inscription remains close to the core-cladding interface of the TCF. The core mode and the cladding mode of the TCF are coupled at the core-mismatch junction, and two well-defined resonances in reflection appear from the downstream FBG, in which the cladding resonance exhibits a strong polarization and bending dependence due to the asymmetrical distribution of the cladding FBG along the fiber cross section. Strong orientation dependence of the vibration (acceleration) measurement has been achieved by power detection of the cladding resonance. Meanwhile, the unwanted power fluctuations and temperature perturbations can be referenced out by monitoring the fundamental core resonance.

  12. A highly sensitive fiber Bragg grating diaphragm pressure transducer

    Science.gov (United States)

    Allwood, Gary; Wild, Graham; Lubansky, Alex; Hinckley, Steven

    2015-10-01

    In this work, a novel diaphragm based pressure transducer with high sensitivity is described, including the physical design structure, in-depth analysis of optical response to changes in pressure, and a discussion of practical implementation and limitations. A flat circular rubber membrane bonded to a cylinder forms the body of the transducer. A fiber Bragg grating bonded to the center of the diaphragm structure enables the fractional change in pressure to be determined by analyzing the change in Bragg wavelength of the reflected spectra. Extensive evaluation of the physical properties and optical characteristics of the transducer has been performed through experimentation, and modeling using small deformation theory. The results show the transducer has a sensitivity of 0.116 nm/kPa, across a range of 15 kPa. Ultra-low cost interrogation of the optical signal was achieved through the use of an optically mismatched Bragg grating acting as an edge filter to convert the spectral change into an intensity change. A numerical model of the intensity based interrogation was implemented in order to validate the experimental results. Utilizing this interrogation technique and housing both the sensing and reference Bragg gratings within the main body of the transducer means it is effectively temperature insensitive and easily connected to electronic systems.

  13. Dynamic high pressure measurements using a Fiber Bragg Grating probe and an arrayed waveguide grating spectrometer

    Science.gov (United States)

    Barbarin, Y.; Lefrançois, A.; Magne, S.; Woirin, K.; Sinatti, F.; Osmont, A.; Luc, J.

    2016-08-01

    High pressure shock profiles are monitored using a long Fiber Bragg Grating (FBG). Such thin probe, with a diameter of typically 150 μm, can be inserted directly into targets for shock plate experiments. The shocked FBG's portion is stressed under compression, which increases its optical group index and shortens its grating period. Placed along the 2D symmetrical axis of the cylindrical target, the second effect is stronger and the reflected spectrum shifts towards the shorter wavelengths. The dynamic evolution of FBG spectra is recorded with a customized Arrayed Waveguide Grating (AWG) spectrometer covering the C+L band. The AWG provides 40 channels of 200-GHz spacing with a special flattop design. The output channels are fiber-connected to photoreceivers (bandwidth: DC - 400 MHz or 10 kHz - 2 GHz). The experimental setup was a symmetric impact, completed in a 110-mm diameter single-stage gas gun with Aluminum (6061T6) impactors and targets. The FBG's central wavelength was 1605 nm to cover the pressure range of 0 - 8 GPa. The FBG was 50-mm long as well as the target's thickness. The 20-mm thick impactor maintains a shock within the target over a distance of 30 mm. For the impact at 522 m/s, the sustained pressure of 3.6 GPa, which resulted in a Bragg shift of (26.2 +/- 1.5) nm, is measured and retrieved with respectively thin-film gauges and the hydrodynamic code Ouranos. The shock sensitivity of the FBG is about 7 nm/GPa, but it decreases with the pressure level. The overall spectra evolution is in good agreement with the numerical simulations.

  14. 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.

  15. Coupled-mode analysis for single-helix chiral fiber gratings with small core-offset

    Institute of Scientific and Technical Information of China (English)

    Li Yang; Linlin Xue; Jue Su; Jingren Qian

    2011-01-01

    Using conventional coupled-mode theory,a set of coupled-mode equations are formulated for single-helix chiral fiber long-period gratings.A helical-core fiber is analyzed as an example.The analysis is simple in mathematical form and intuitive in physical concept.Based on the analysis,the polarization independence of mode coupling in special fiber gratings is revealed.The transmission characteristics of helical-core fibers are also simulated and discussed.

  16. Certification of a submarine design using fiber Bragg grating sensors

    Science.gov (United States)

    Kiddy, Jason S.; Baldwin, Chris S.; Salter, Toni J.

    2004-07-01

    Systems Planning and Analysis, Inc. (SPA) has recently planned, installed, and tested a fiber Bragg grating (FBG) strain sensor system to validate FEM predictions of a new submarine design undergoing American Bureau of Shipping (ABS) certification testing. Fiber optic triaxial, biaxial, and uniaxial gage locations were selected based on the FEM analysis. FBGs were placed on six optical fibers with two fibers (33 sensors) mounted internally to the hull and four fibers (64 sensors) mounted externally. Testing was performed by lowering the submarine to the design depth and recording strain measurements. The optical sensor signals were transmitted directly to the water's surface and monitored by top-side interrogation instrumentation through over 2000 feet of optical cable. Measured temperature-compensated strain values were compared to the FEM predicted strain values with excellent results. To the author's knowledge, this successful test represents the first time that FBG sensors have been used to certify a submarine design and to validate FEM analysis on a large-scale structure.

  17. Polyimide-coated fiber Bragg grating for relative humidity sensing

    Science.gov (United States)

    Lin, Yao; Gong, Yuan; Wu, Yu; Wu, Huijuan

    2015-03-01

    A fiber-optic humidity sensor has been fabricated by coating a moisture sensitive polymer film to the fiber Bragg grating (FBG). The Bragg wavelength of the polyimide-coated FBG changes while it is exposed to different humidity conditions due to the volume expansion of the polyimide coating. The characteristics of sensors, including sensitivity, temporal response, and hysteresis, were improved by controlling the coating thickness and the degree of imidization during the thermal curing process of the polyimide. In the relative humidity (RH) condition ranging from 11.3% RH to 97.3% RH, the sensitivity of the sensor was about 13.5 pm/% RH with measurement uncertainty of ±1.5% RH.

  18. 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.

  19. 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 linear...... up to at least 15 g and sensitivities as high as 19 pm/g (shift in resonance wavelength per unit acceleration) have been demonstrated. Given that 15 g corresponds to a strain of less than 0.02% and that polymer fibers have an elastic limit of more than 1%, the polymer FBG accelerometer can measure...... very strong accelerations. We compare with corresponding silica FBG accelerometers and demonstrate that using polymer FBGs improves the sensitivity by more than a factor of four and increases the figure of merit, defined as the sensitivity times the resonance frequency squared....

  20. Influence of Humidity on Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Ander Montero

    2014-01-01

    Full Text Available We demonstrate the influence of the relative humidity (RH on the wavelength of fiber Bragg grating sensors (FBGS, performing tests with five FBGS at different humidity and temperature conditions. These tests were performed in a climate chamber whose RH changes according to a scheduled profile from 30% to 90%, in steps of 10%. These profiles were repeated for a wide range of temperatures from 10∘C to 70∘C, in steps of 10∘C. Two different types of instrumentation methods have been tested, spot welding and epoxy bonding, in two different materials, steel and carbon fiber reinforced polymer (CFRP. We discuss the results for each type of sensor and instrumentation method by analyzing the linearity of the Bragg wavelength with RH and temperature.

  1. [INVITED] New advances in polymer fiber Bragg gratings

    Science.gov (United States)

    Nogueira, Rogério; Oliveira, Ricardo; Bilro, Lúcia; Heidarialamdarloo, Jamshid

    2016-04-01

    During the last years, fiber Bragg gratings (FBGs) written in polymer optical fibers (POFs) have been pointed as an interesting alternative to silica FBGs for applications in sensors and in optical access networks. In order to use such components in real applications, the manipulation of POFs, as well as the increase of quality in the production of FBGs has to be achieved. In this article some of the recent advances regarding these two aspects are reported and include recent developments to produce smooth POFs end face with high quality, benefiting the current splicing process and the inscription of high quality FBGs in a few seconds. Furthermore, additional characterizations to strain, temperature, pressure, and humidity are also shown.

  2. 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

  3. 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.

  4. Thermal and chemical treatment of polymer optical fiber Bragg grating sensors for enhanced mechanical sensitivity

    DEFF Research Database (Denmark)

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

    2017-01-01

    An investigation of the thermal annealing effects on the strain, stress, and force sensitivities of polymer optical fiber Bragg grating sensors is performed. We demonstrate for the first time that the fiber annealing can enhance both stress and force sensitivities of Bragg grating sensors, with t...

  5. Grating writing and growth at 325nm in non-hydrogenated silica fiber

    DEFF Research Database (Denmark)

    Town, Graham E; Yuan, Scott Wu; Stefani, Alessio;

    We report on the writing and growth dynamics of Bragg gratings written in standard silica fiber using a 325nm He:Cd laser.......We report on the writing and growth dynamics of Bragg gratings written in standard silica fiber using a 325nm He:Cd laser....

  6. 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.

  7. Bragg-grating-based all-fiber distributed Gires-Tournois etalons

    Science.gov (United States)

    Shu, Xuewen; Sugden, Kate; Byron, Kevin

    2003-06-01

    We report, for the first time to our knowledge, achievement of all-fiber distributed Gires-Tournois etalons (DGTEs) based on fiber Bragg gratings. DGTEs with both separated structure and overlapped structure were investigated. Such grating-based DGTEs show periodic spectral characteristics that are similar to those of conventional Gires-Tournois etalons; however, they also have some particular characteristics that are due to the dispersive nature of the gratings.

  8. 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.

  9. Fiber Bragg grating sensor-based communication assistance device

    Science.gov (United States)

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

    2016-08-01

    Improvements in emergency medicine in the form of efficient life supporting systems and intensive care have increased the survival rate in critically injured patients; however, in some cases, severe brain and spinal cord injuries can result in a locked-in syndrome or other forms of paralysis, and communication with these patients may become restricted or impossible. The present study proposes a noninvasive, real-time communication assistive methodology for those with restricted communication ability, employing a fiber Bragg grating (FBG) sensor. The communication assistive methodology comprises a breath pattern analyzer using an FBG sensor, which acquires the exhalation force that is converted into strain variations on a cantilever. The FBG breath pattern analyzer along with specific breath patterns, which are programmed to give specific audio output commands, constitutes the proposed fiber Bragg grating sensor-based communication assistive device. The basic communication can be carried out by instructing the patients with restricted communication ability to perform the specific breath patterns. The present approach is intended to be an alternative to the common approach of brain-computer interface in which an instrument is utilized for learning of brain responses.

  10. Structurally embedded fiber Bragg gratings: civil engineering applications

    Science.gov (United States)

    Nellen, Philipp M.; Broennimann, Rolf; Frank, Andreas; Mauron, Pascal; Sennhauser, Urs J.

    1999-12-01

    In civil engineering it is of interest to monitor long-term performance of structures made of new lightweight materials like glass or carbon fiber reinforced polymers (GFRP/CFRP). In contrast to surface applied optical fiber sensors, embedded sensors are expected to be better protected against rough handling and harsh environmental conditions. We report on two recently done fiber optical sensor applications in civil engineering. Both include structurally embedded fiber Bragg grating (BG) arrays but have different demands with respect to their operation. For the first application fiber BGs were embedded in GFRP rockbolts of 3 - 5 m in length either of 3, 8, or 22 mm diameter. The sensor equipped rockbolts are made for distributed measurements of boulder motion during tunnel construction and operation and should withstand strain up to 1.6%. Rockbolt sensors were field tested in a tunnel near Sargans in Switzerland. For a second application fiber BGs were embedded in CFRP wires of 5 mm diameter used for the pre- stressing cables of a 56 m long bridge near Lucerne in Switzerland. The permanent load on the cable corresponds to 0.8% strain. Due to the embedded sensors, strain decay inside the cable anchoring heads could be measured for the first time during loading and operation of the cables. For both applications mechanical and thermal loading tests were performed to assess the function of these new elements. Also, temperature and strain sensitivity were calibrated. Reliability studies with respect to stress transfer, fiber mechanical failure, and wavelength shift caused by thermal BG decay as well as monitoring results of both applications are presented.

  11. Fiber optic anemometer based on metal infiltrated microstructured optical fiber inscribed with Bragg grating

    Science.gov (United States)

    Wang, Jie; Gao, Shaorui; Liu, Zhengyong; Zhang, A. Ping; Shen, Yonghang; Tam, Hwayaw

    2015-09-01

    An all-fiber optical anemometer with high light-heat conversion efficiency by using an in-house microstructured optical fiber Bragg grating (MOFBG) is presented. Low-molten-temperature BiSnIn alloy was successfully infiltrated into 11- cm length of a six-hole microstructured optical fiber which was inscribed with a fibre Bragg grating (FBG) centered at ~848 nm. Light launched into the MOFBG was strongly absorbed by the metal to generate heat, while the FBG was utilized to monitor temperature change due to surrounding wind speed. The sensitivity of the laser-heated MOFBG anemometer was measured to be ~0.1 nm/(m/s) for wind speed ranged from 0.5 m/s to 2 m/s. The efficiency of the anemometer, defined as effective sensitivity per pump power, is 8.7 nm/(m/s*W).

  12. 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.

  13. Evaluation of Fiber Bragg Grating and Distributed Optical Fiber Temperature Sensors

    Energy Technology Data Exchange (ETDEWEB)

    McCary, Kelly Marie [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-04-01

    Fiber optic temperature sensors were evaluated in the High Temperature Test Lab (HTTL) to determine the accuracy of the measurements at various temperatures. A distributed temperature sensor was evaluated up to 550C and a fiber Bragg grating sensor was evaluated up to 750C. HTTL measurements indicate that there is a drift in fiber Bragg sensor over time of approximately -10C with higher accuracy at temperatures above 300C. The distributed sensor produced some bad data points at and above 500C but produced measurements with less than 2% error at increasing temperatures up to 400C

  14. FIBER LASER CONSTRUCTION AND THEORY INCLUDING FIBER BRAGG GRATINGS Photonic Crystal Fibers (PCFs) and applications of gas filled PCFs

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, Jacob O. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-08

    The principles used in fiber lasers have been around for a while but it is only within the past few years that fiber lasers have become commercially available and used in high power laser applications. This paper will focus on the basic design principles of fiber lasers, including fiber Bragg gratings, principles of operation, and forms of non-linear effects. It will describe the type and associated doping of the fiber used and difficult designs used to guide energy from the pump to the active medium. Topics covered include fiber laser design, fiber Bragg gratings, materials used, differences in quantum energy loss, thermo-optical effects, stimulated Raman scattering, Brillouin scattering, photonic crystal fibers and applications of gas filled Photonic Crystal Fibers (PCFs). Thanks to fiber lasers, the energy required to produce high power lasers has greatly dropped and as such we can now produce kW power using a standard 120V 15A circuit. High power laser applications are always requiring more power. The fiber laser can now deliver the greater power that these applications demand. Future applications requiring more power than can be combined using standard materials or configurations will need to be developed to overcome the high energy density and high non-linear optical scattering effects present during high power operations.

  15. Magneto-Optic Fiber Gratings Useful for Dynamic Dispersion Management and Tunable Comb Filtering

    Science.gov (United States)

    Wu, Bao-Jian; Lu, Xin; Qiu, Kun

    2010-06-01

    Intelligent control of dispersion management and tunable comb filtering in optical network applications can be performed by using magneto-optic fiber Bragg gratings (MFBGs). When a nonuniform magnetic field is applied to the MFBG with a constant grating period, the resulting grating response is equivalent to that of a conventional chirped grating. Under a linearly nonuniform magnetic field along the grating, a linear dispersion is achieved in the grating bandgap and the maximal dispersion slope can come to 1260 ps/nm2 for a 10-mm-long fiber grating at 1550 nm window. Similarly, a Gaussian-apodizing sampled MFBG is also useful for magnetically tunable comb filtering, with potential application to clock recovery from return-to-zero optical signals and optical carrier tracking.

  16. Dual wavelength erbium-doped fiber laser with a lateral pressure-tuned Hi-Bi fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    Lingyun Xiong(熊凌云); Guiyun Kai(开桂云); Lei Sun(孙磊); Xinhuan Feng(冯新焕); Chunxian Xiao(肖纯贤); Yange Liu(刘艳格); Shuzhong Yuan(袁树忠); Xiaoyi Dong(董孝义)

    2004-01-01

    Tunable dual wavelength erbium-doped fiber laser (EDFL) with stable oscillation at room temperature is proposed and demonstrated. This laser utilizes a Bragg grating fabricated in a high birefringence fiber as the wavelength-selective component, and then achieves the stable dual wavelength oscillation by introducing the polarization hole burning effect. Furthermore, by applying lateral strain upon the fiber Bragg grating (FBG), the space of the laser dual wavelengths can be tuned continuously.

  17. All-optical fiber anemometer based on laser heated fiber Bragg gratings.

    Science.gov (United States)

    Gao, Shaorui; Zhang, A Ping; Tam, Hwa-Yaw; Cho, L H; Lu, Chao

    2011-05-23

    A fiber-optic anemometer based on fiber Bragg gratings (FBGs) is presented. A short section of cobalt-doped fiber was utilized to make a fiber-based "hot wire" for wind speed measurement. Fiber Bragg gratings (FBGs) were fabricated in the cobalt-doped fiber using 193 nm laser pulses to serve as localized temperature sensors. A miniature all-optical fiber anemometer is constructed by using two FBGs to determine the dynamic thermal equilibrium between the laser heating and air flow cooling through monitoring the FBGs' central wavelengths. It was demonstrated that the sensitivity of the sensor can be adjusted through the power of pump laser or the coating on the FBG. Experimental results reveal that the proposed FBG-based anemometer exhibits very good performance for wind speed measurement. The resolution of the FBG-based anemometer is about 0.012 m/s for wind speed range between 2.0 m/s and 8.0 m/s.

  18. 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.

  19. A New Idea and Technique of Fiber Gratings and Photodetectors in Broad-band Fiber Communication Systems

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Contents of this thesis are supported by the National Natural Foudation of China under Contract No.69625101, and the item is named “Tunable Optical Technology in Wavelength Division Multiplexing (WDM)” and is under charge of Professor Ren Xiaomin. They are also supported by subject 307 in National Program “863”: i.e., RCE photodetectors (PDs) used in Wavelength Division Multiplexing. Fiber Bragg Gratings (FBGs) have emerged as important optical fiber passive components in a variety of light-wave applications. It is expected that FBGs will play a key role in the next generation of optical fiber communication systems and sensor fileds. Most of these applications are based on the narrow-band reflection of FBGs. In this thesis, transmission dispersion, nonlinearity and tunability of FBGs are studied. The main contents are as follows: Transmission dispersion of FBGs is studied and the capability of dispersion compensation of FBGs is calculated theoretically. In the experiments, the dispersions of 10 Gb/s at 11.1 km and 22.22 km are compensated successfully by an unchirped fiber grating for the first time in China and the tunable compensation is achieved for the first time internationally. The scheme of tunable dispersion compensation using cascaded fiber gratings in WDM is analyzed and designed. It is indicated that the dispersion compensation in transmission using uniform fiber gratings is a better and more effective compensation scheme compared with the tradifitonal dispersion compensation using chirped fiber gratings. It is originally proposed that people can simulate characteristics of a long distance optical fiber by a short uniform fiber grating. This is verified for the first time experimentally. In the experiment, a short grating (about 1 cm) operated in transmission is used to simulate pulse broadening of 11.1 km optical fiber. This method can be used to detect performance of long distance transmission of communication systems. It is originally proposed

  20. Switchable dual-mode all-fiber laser with few-mode fiber Bragg grating

    Science.gov (United States)

    Jin, Wenxing; Qi, Yanhui; Yang, Yuguang; Jiang, Youchao; Wu, Yue; Xu, Yao; Yao, Shuzhi; Jian, Shuisheng

    2017-09-01

    We propose a new approach to realize switchable mode operation in a few-mode erbium-doped fiber laser. The ring fiber laser structure is constructed with a core-offset splicing between single-mode fiber and dual-mode fiber. Stable operating on the fundamental mode laser and second-order mode laser individually or simultaneously is realized by appropriately adjusting the state of the polarization controller and bending status of the few-mode fiber Bragg grating. The narrow 3 dB linewidth less than 0.02 nm and high optical signal to noise ratio more than 42 dB are obtained for both modes in either separate laser or simultaneous laser operating conditions.

  1. Design and optimization of mode converter based on long period fiber grating

    Science.gov (United States)

    Xiang, Qian; Chang, Li-Jun; Chen, Ming-Yang

    2016-10-01

    A novel mode converter which is based on long period fiber grating (LPFG) is proposed. A graded-index optical fiber is introduced to induce strong mode coupling at wide bandwidth. By optimize the fiber configuration and parameters, and the appropriate choice of grating parameter, high mode conversion efficiency with cross-talk lower than -20 dB and wide operation bandwidth over 180 nm can be achieved.

  2. Numerical Analysis on Transmission Characteristics of a Bragg Grating Assisted Mismatched Fiber Coupler

    Institute of Scientific and Technical Information of China (English)

    WEI Daoping; JIANG Zhong'ao; ZHAO Yucheng; JIAN Shuisheng

    2000-01-01

    Based on mode-coupled theory, a Bragg grating assisted mismatched fiber coupler is analyzed theoretically. At the same time, a detailed numerical analysis on transmission characteristics of the coupler is carried out when it considers the arcs of two fibers in the coupling region of the coupler or not, and the optimized design on the Bragg grating assisted mismatched fiber coupler for wavelength-division multiplexing/ demultiplexing is proposed.

  3. 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.

  4. Sensing delamination in epoxy encapsulant systems with fiber Bragg gratings

    Science.gov (United States)

    Jones, Brad H.; Rohr, Garth D.; Kaczmarowski, Amy K.

    2016-05-01

    Fiber Bragg gratings (FBGs) are well-suited for embedded sensing of interfacial phenomena in materials systems, due to the sensitivity of their spectral response to locally non-uniform strain fields. Over the last 15 years, FBGs have been successfully employed to sense delamination at interfaces, with a clear emphasis on planar events induced by transverse cracks in fiber-reinforced plastic laminates. We have built upon this work by utilizing FBGs to detect circular delamination events at the interface between epoxy films and alumina substrates. Two different delamination processes are examined, based on stress relief induced by indentation of the epoxy film or by cooling to low temperature. We have characterized the spectral response pre- and post-delamination for both simple and chirped FBGs as a function of delamination size. We show that delamination is readily detected by the evolution of a non-uniform strain distribution along the fiber axis that persists after the stressing condition is removed. These residual strain distributions differ substantially between the delamination processes, with indentation and cooling producing predominantly tensile and compressive strain, respectively, that are well-captured by Gaussian profiles. More importantly, we observe a strong correlation between spectrally-derived measurements, such as spectral widths, and delamination size. Our results further highlight the unique capabilities of FBGs as diagnostic tools for sensing delamination in materials systems.

  5. Highly sensitive fiber-optic accelerometer by grating inscription in specific core dip fiber.

    Science.gov (United States)

    Rong, Qiangzhou; Guo, Tuan; Bao, Weijia; Shao, Zhihua; Peng, Gang-Ding; Qiao, Xueguang

    2017-09-19

    A highly sensitive fiber-optic accelerometer based on detecting the power output of resonances from the core dip is demonstrated. The sensing probe comprises a compact structure, hereby a short section of specific core (with a significant core dip) fiber stub containing a straight fiber Bragg grating is spliced to another single-mode fiber via a core self-alignment process. The femtosecond laser side-illumination technique was utilized to ensure that the grating inscription region is precisely positioned and compact in size. Two well-defined core resonances were achieved in reflection: one originates from the core dip and the other originates from fiber core. The key point is that only one of these two reflective resonances exhibits a high sensitivity to fiber bend (and vibration), whereas the other is immune to it. For low frequency (core mode reflection. Moreover, the sensor simultaneously provides an inherent power reference to eliminate unwanted power fluctuations from the light source and transmission lines, thus providing a means of evaluating weak seismic wave at low frequency.

  6. 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.

  7. Radial arterial compliance measurement by fiber Bragg grating pulse recorder.

    Science.gov (United States)

    Sharath, U; Shwetha, C; Anand, K; Asokan, S

    2014-12-01

    In the present work, we report a novel, in vivo, noninvasive technique to determine radial arterial compliance using the radial arterial pressure pulse waveform (RAPPW) acquired by fiber Bragg grating pulse recorder (FBGPR). The radial arterial compliance of the subject can be measured during sphygmomanometric examination by the unique signatures of arterial diametrical variations and the beat-to-beat pulse pressure acquired simultaneously from the RAPPW recorded using FBGPR. This proposed technique has been validated against the radial arterial diametrical measurements obtained from the color Doppler ultrasound. Two distinct trials have been illustrated in this work and the results from both techniques have been found to be in good agreement with each other.

  8. 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.

  9. 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.

  10. An investigation of interface transferring mechanism of surface-bonded fiber Bragg grating sensors

    Science.gov (United States)

    Wu, Rujun; Fu, Kunkun; Chen, Tian

    2017-08-01

    Surface-bonded fiber Bragg grating sensor has been widely used in measuring strain in materials. The existence of fiber Bragg grating sensor affects strain distribution of the host material, which may result in a decrease in strain measurement accuracy. To improve the measurement accuracy, a theoretical model of strain transfer from the host material to optical fiber was developed, incorporating the influence of the fiber Bragg grating sensor. Subsequently, theoretical predictions were validated by comparing with data from finite element analysis and the existing experiment [F. Ansari and Y. Libo, J. Eng. Mech. 124(4), 385-394 (1998)]. Finally, the effect of parameters of fiber Bragg grating sensors on the average strain transfer rate was discussed.

  11. Huge capacity fiber-optic sensing network based on ultra-weak draw tower gratings

    Science.gov (United States)

    Yang, Minghong; Bai, Wei; Guo, Huiyong; Wen, Hongqiao; Yu, Haihu; Jiang, Desheng

    2016-03-01

    This paper reviews the work on huge capacity fiber-optic sensing network based on ultra-weak draw tower gratings developed at the National Engineering Laboratory for Fiber Optic Sensing Technology (NEL-FOST), Wuhan University of Technology, China. A versatile drawing tower grating sensor network based on ultra-weak fiber Bragg gratings (FBGs) is firstly proposed and demonstrated. The sensing network is interrogated with time- and wavelength-division multiplexing method, which is very promising for the large-scale sensing network.

  12. Measuring water activity of aviation fuel using a polymer optical fiber Bragg grating

    Science.gov (United States)

    Zhang, Wei; Webb, David J.; Carpenter, Mark; Williams, Colleen

    2014-05-01

    Poly(methyl methacrylate) (PMMA) based polymer optical fiber Bragg gratings have been used for measuring water activity of aviation fuel. Jet A-1 samples with water content ranging from 100% ERH (wet fuel) to 10 ppm (dried fuel), have been conditioned and calibrated for measurement. The PMMA based optical fiber grating exhibits consistent response and a good sensitivity of 59±3pm/ppm (water content in mass). This water activity measurement allows PMMA based optical fiber gratings to detect very tiny amounts of water in fuels that have a low water saturation point, potentially giving early warning of unsafe operation of a fuel system.

  13. Waveform reconstruction for an ultrasonic fiber Bragg grating sensor demodulated by an erbium fiber laser.

    Science.gov (United States)

    Wu, Qi; Okabe, Yoji

    2015-02-01

    Fiber Bragg grating (FBG) demodulated by an erbium fiber laser (EFL) has been used for ultrasonic detection recently. However, due to the inherent relaxation oscillation (RO) of the EFL, the detected ultrasonic signals have large deformations, especially in the low-frequency range. We proposed a novel data processing method to reconstruct an actual ultrasonic waveform. The noise spectrum was smoothed first; the actual ultrasonic spectrum was then obtained by deconvolution in order to mitigate the influence of the RO of the EFL. We proved by experiment that this waveform reconstruction method has high precision, and demonstrated that the FBG sensor demodulated by the EFL will have large practical applications in nondestructive testing.

  14. Bandpass transmission filters based on phase shifted fiber Bragg gratings in microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Ortega, Beatriz; Min, Rui; Sáez-Rodri­guez, David

    2017-01-01

    In this contribution we report on the fabrication of novel bandpass transmission filters based on PS-FBGs in microstructured polymer fibers at telecom wavelengths. The phase mask technique is employed to fabricate several superimposed gratings with slight different periods in order to form Moir......é structures with a single or various π phase shifts along the device. Simulations and experimental results are included in order to demonstrate very narrowband transmission filters. Experimental characterization under strain and temperature variations is provided in a non-annealed fiber and time stability...

  15. 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.

  16. Resonances in coated long period fiber gratings and cladding removed multimode optical fibers: a comparative study.

    Science.gov (United States)

    Del Villar, Ignacio; Zamarreño, Carlos R; Hernaez, Miguel; Arregui, Francisco J; Matias, Ignacio R

    2010-09-13

    Two optical fiber devices have been coated in parallel: a long period fiber grating (LPFG) and a cladding-removed multimode optical fiber (CRMOF). The progressive coating of the LPFG by means of the layer-by-layer electrostatic-self-assembly, permits to observe a resonance wavelength shift of the attenuation bands in the transmission spectrum. The cause of this wavelength shift is the reorganization of the cladding mode effective indices. The cause of this modal reorganization can be understood with the results observed in the CRMOF coated in parallel. A lossy-mode-resonance (LMR) is generated in the same wavelength range of the LPFG attenuation bands analyzed. Moreover, the thickness range where the wavelength shift of the LPFG attenuation bands occurs coincides exactly with the thickness range where the LMR can be visualized in the transmission spectrum. These phenomena are analyzed theoretically and corroborated experimentally. The advantages and disadvantages of both optical fiber devices are explained.

  17. 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.

  18. Study of a single longitudinal fiber ring laser with a π phase-shifted fiber Bragg grating

    Science.gov (United States)

    Wang, Weitao; Song, Zhiqiang; Qi, Haifeng; Zhang, Xiaolei; Ni, Jiasheng; Guo, Jian; Wang, Chang; Peng, Gangding

    2017-08-01

    A single-longitudinal-mode fiber laser is presented, which is composed of a ring cavity laser and a π phase-shifted fiber Bragg grating. The ring cavity structure can reduce the spatial hole burning, but the mode hopping and competition are still existing due to the long fiber ring cavity length. The π phase-shifted fiber Bragg grating has very narrow transmittance spectrum width as a band-pass filter. Combined with a wavelength-matching fiber Bragg grating, it is able to efficiently suppress the mode hopping and competition in the ring cavity. The single longitudinal mode lasing is verified using a scanning F-P interferometer. Its frequency noise is measured by the self-homodyne technology with a 3×3 optical fiber coupler. The calculated linewidth from the frequency noise is about 21 kHz when the measurement time is 0.2 s.

  19. Small biomolecule immunosensing with plasmonic optical fiber grating sensor.

    Science.gov (United States)

    Ribaut, Clotilde; Voisin, Valérie; Malachovská, Viera; Dubois, Valentin; Mégret, Patrice; Wattiez, Ruddy; Caucheteur, Christophe

    2016-03-15

    This study reports on the development of a surface plasmon resonance (SPR) optical fiber biosensor based on tilted fiber Bragg grating technology for direct detection of small biomarkers of interest for lung cancer diagnosis. Since SPR principle relies on the refractive index modifications to sensitively detect mass changes at the gold coated surface, we have proposed here a comparative study in relation to the target size. Two cytokeratin 7 (CK7) samples with a molecular weight ranging from 78 kDa to 2.6 kDa, respectively CK7 full protein and CK7 peptide, have been used for label-free monitoring. This work has first consisted in the elaboration and the characterization of a robust and reproducible bioreceptor, based on antibody/antigen cross-linking. Immobilized antibodies were then utilized as binding agents to investigate the sensitivity of the biosensor towards the two CK7 antigens. Results have highlighted a very good sensitivity of the biosensor response for both samples diluted in phosphate buffer with a higher limit of detection for the larger CK7 full protein. The most groundbreaking nature of this study relies on the detection of small biomolecule CK7 peptides in buffer and in the presence of complex media such as serum, achieving a limit of detection of 0.4 nM.

  20. A Fiber Bragg Grating Sensing Based Triaxial Vibration Sensor.

    Science.gov (United States)

    Li, Tianliang; Tan, Yuegang; Liu, Yi; Qu, Yongzhi; Liu, Mingyao; Zhou, Zude

    2015-09-18

    A fiber Bragg grating (FBG) sensing based triaxial vibration sensor has been presented in this paper. The optical fiber is directly employed as elastomer, and the triaxial vibration of a measured body can be obtained by two pairs of FBGs. A model of a triaxial vibration sensor as well as decoupling principles of triaxial vibration and experimental analyses are proposed. Experimental results show that: sensitivities of 86.9 pm/g, 971.8 pm/g and 154.7 pm/g for each orthogonal sensitive direction with linearity are separately 3.64%, 1.50% and 3.01%. The flat frequency ranges reside in 20-200 Hz, 3-20 Hz and 4-50 Hz, respectively; in addition, the resonant frequencies are separately 700 Hz, 40 Hz and 110 Hz in the x/y/z direction. When the sensor is excited in a single direction vibration, the outputs of sensor in the other two directions are consistent with the outputs in the non-working state. Therefore, it is effectively demonstrated that it can be used for three-dimensional vibration measurement.

  1. Diaphragm Based Fiber Bragg Grating Acceleration Sensor with Temperature Compensation.

    Science.gov (United States)

    Li, Tianliang; Tan, Yuegang; Han, Xue; Zheng, Kai; Zhou, Zude

    2017-01-23

    A novel fiber Bragg grating (FBG) sensing-based acceleration sensor has been proposed to simultaneously decouple and measure temperature and acceleration in real-time. This design applied a diaphragm structure and utilized the axial property of a tightly suspended optical fiber, enabling improvement in its sensitivity and resonant frequency and achieve a low cross-sensitivity. The theoretical vibrational model of the sensor has been built, and its design parameters and sensing properties have been analyzed through the numerical analysis. A decoupling method has been presented with consideration of the thermal expansion of the sensor structure to realize temperature compensation. Experimental results show that the temperature sensitivity is 8.66 pm/°C within the range of 30-90 °C. The acceleration sensitivity is 20.189 pm/g with a linearity of 0.764% within the range of 5~65 m/s². The corresponding working bandwidth is 10~200 Hz and its resonant frequency is 600 Hz. This sensor possesses an excellent impact resistance for the cross direction, and the cross-axis sensitivity is below 3.31%. This implementation can avoid the FBG-pasting procedure and overcome its associated shortcomings. The performance of the proposed acceleration sensor can be easily adjusted by modifying their corresponding physical parameters to satisfy requirements from different vibration measurements.

  2. Diaphragm Based Fiber Bragg Grating Acceleration Sensor with Temperature Compensation

    Directory of Open Access Journals (Sweden)

    Tianliang Li

    2017-01-01

    Full Text Available A novel fiber Bragg grating (FBG sensing-based acceleration sensor has been proposed to simultaneously decouple and measure temperature and acceleration in real-time. This design applied a diaphragm structure and utilized the axial property of a tightly suspended optical fiber, enabling improvement in its sensitivity and resonant frequency and achieve a low cross-sensitivity. The theoretical vibrational model of the sensor has been built, and its design parameters and sensing properties have been analyzed through the numerical analysis. A decoupling method has been presented with consideration of the thermal expansion of the sensor structure to realize temperature compensation. Experimental results show that the temperature sensitivity is 8.66 pm/°C within the range of 30–90 °C. The acceleration sensitivity is 20.189 pm/g with a linearity of 0.764% within the range of 5~65 m/s2. The corresponding working bandwidth is 10~200 Hz and its resonant frequency is 600 Hz. This sensor possesses an excellent impact resistance for the cross direction, and the cross-axis sensitivity is below 3.31%. This implementation can avoid the FBG-pasting procedure and overcome its associated shortcomings. The performance of the proposed acceleration sensor can be easily adjusted by modifying their corresponding physical parameters to satisfy requirements from different vibration measurements.

  3. Long period gratings written in large-mode area photonic crystal fiber

    DEFF Research Database (Denmark)

    Nodop, D.; Linke, S.; Jansen, F.

    2008-01-01

    We report for the first time, to the best of our knowledge, on the fabrication and characterization of CO2-laser written long-period gratings in a large-mode area photonic crystal fiber with a core diameter of 25 mu m. The gratings have low insertion losses ( 10 d...

  4. 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.

  5. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Abbaneo, D.; Abbas, M. [CERN, Geneva (Switzerland); Abbrescia, M. [INFN Bari and University of Bari, Bari (Italy); Abdelalim, A.A. [Helwan University & CTP, Cairo (Egypt); Abi Akl, M. [Texas A& M University at Qatar, Doha (Qatar); Aboamer, O. [Academy of Scientific Research and Technology – Egyptian Network of High Energy Physics, ASRT-ENHEP, Cairo (Egypt); Acosta, D. [University of Florida, Gainesville (United States); Ahmad, A. [National Center for Physics, Quaid-i-Azam University Campus, Islamabad (Pakistan); Ahmed, W. [Helwan University & CTP, Cairo (Egypt); Ahmed, W. [National Center for Physics, Quaid-i-Azam University Campus, Islamabad (Pakistan); Aleksandrov, A. [Institute for Nuclear Research and Nuclear Energy, Sofia (Bulgaria); Aly, R. [Helwan University & CTP, Cairo (Egypt); Altieri, P. [INFN Bari and University of Bari, Bari (Italy); Asawatangtrakuldee, C. [Peking University, Beijing (China); Aspell, P. [CERN, Geneva (Switzerland); Assran, Y. [Academy of Scientific Research and Technology – Egyptian Network of High Energy Physics, ASRT-ENHEP, Cairo (Egypt); Awan, I. [National Center for Physics, Quaid-i-Azam University Campus, Islamabad (Pakistan); Bally, S. [CERN, Geneva (Switzerland); Ban, Y. [Peking University, Beijing (China); Banerjee, S. [Saha Institute of Nuclear Physics, Kolkata (India); and others

    2016-07-11

    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.

  7. Variation of Lasing Wavelength of Fiber Grating Semiconductor Laser with Temperature for Different External Cavity Lengths

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    For different external cavity lengths, lasing wavelength variation of fiber grating external cavity semiconductor laser (FGECSL) with ambient temperature has been investigated theoretically, and the theoretical results are in agreement with reported experimental observations.

  8. 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.

  9. A technique for enhancing the thermal stability of hydrogen-loaded fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    Youlong Yu(余有龙); Hwayaw Tam(谭华耀)

    2003-01-01

    Heat treatment with the presence of hydrogen (H2) that react with GeE' centers (.Ge ≡) at high tem-perature will weaken the refractive index modulation of grating fabricated in hydrogen-loaded normalgermanosilicate fiber. Pre-annealing treatment of the above fiber was demonstrated to be able to enhancethe grating's thermal stability effectively. 0.37-nm blue-shift of the reflected Bragg wavelength was ob-served.

  10. Temperature sensing of micron scale polymer fibers using fiber Bragg gratings

    KAUST Repository

    Zhou, J.

    2015-07-02

    Highly conductive polymer fibers are key components in the design of multifunctional textiles. Measuring the voltage/temperature relationships of these fibers is very challenging due to their very small diameters, making it impossible to rely on classical temperature sensing techniques. These fibers are also so fragile that they cannot withstand any perturbation from external measurement systems. We propose here, a non-contact temperature measurement technique based on fiber Bragg gratings (FBGs). The heat exchange is carefully controlled between the probed fibers and the sensing FBG by promoting radiation and convective heat transfer rather than conduction, which is known to be poorly controlled. We demonstrate our technique on a highly conductive Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS)-based fiber. A non-phenomenological model of the sensing system based on meaningful physical parameters is validated towards experimental observations. The technique reliably measures the temperature of the polymer fibers when subjected to electrical loading. © 2015 IOP Publishing Ltd.

  11. Tunable Fiber Bragg Grating Ring Lasers using Macro Fiber Composite Actuators

    Science.gov (United States)

    Geddis, Demetris L.; Allison, Sidney G.; Shams, Qamar A.

    2006-01-01

    The research reported herein includes the fabrication of a tunable optical fiber Bragg grating (FBG) fiber ring laser (FRL)1 from commercially available components as a high-speed alternative tunable laser source for NASA Langley s optical frequency domain reflectometer (OFDR) interrogator, which reads low reflectivity FBG sensors. A Macro-Fiber Composite (MFC) actuator invented at NASA Langley Research Center (LaRC) was selected to tune the laser. MFC actuators use a piezoelectric sheet cut into uniaxially aligned rectangular piezo-fibers surrounded by a polymer matrix and incorporate interdigitated electrodes to deliver electric fields along the length of the piezo-fibers. This configuration enables MFC actuators to produce displacements larger than the original uncut piezoelectric sheet. The FBG filter was sandwiched between two MFC actuators, and when strained, produced approximately 3.62 nm of wavelength shift in the FRL when biasing the MFC actuators from 500 V to 2000 V. This tunability range is comparable to that of other tunable lasers and is adequate for interrogating FBG sensors using OFDR technology. Three different FRL configurations were studied. Configuration A examined the importance of erbium-doped fiber length and output coupling. Configuration B demonstrated the importance of the FBG filter. Configuration C added an output coupler to increase the output power and to isolate the filter. Only configuration C was tuned because it offered the best optical power output of the three configurations. Use of Plastic Optical Fiber (POF) FBG s holds promise for enhanced tunability in future research.

  12. Sub-100 fs mode-locked erbium-doped fiber laser using a 45°-tilted fiber grating.

    Science.gov (United States)

    Zhang, Zuxing; Mou, Chengbo; Yan, Zhijun; Zhou, Kaiming; Zhang, Lin; Turitsyn, Sergei

    2013-11-18

    We demonstrate generation of sub-100 fs pulses at 1.5 µm in a mode-locked erbium-doped fiber laser using a 45°-tilted fiber grating element. The laser features a genuine all-fiber configuration. Based on the unique polarization properties of the 45°-tilted fiber grating, we managed to produce sub-100 fs laser pulses through proper dispersion management. To the best of our knowledge, this is the shortest pulse generated from mode-locked lasers with fiber gratings. The output pulse has an average power of 8 mW, with a repetition rate of 47.8 MHz and pulse energy of 1.68 nJ. The performance of laser also matches well the theoretical simulations.

  13. UV-transparent fluoropolymer fiber coating for the inscription of chirped Bragg gratings arrays

    Science.gov (United States)

    Tokarev, Alexey V.; Anchutkin, Gordey G.; Varzhel, Sergey V.; Gribaev, Alexey I.; Kulikov, Andrey V.; Meshkovskiy, Igor K.; Rothhardt, Manfred; Elsmann, Tino; Becker, Martin; Bartelt, Hartmut

    2017-03-01

    A fluoropolymer optical fiber coating based on the thermoplastic copolymer of chlorotrifluoroethylene and vinylidene fluoride is presented. Such coatings can be used as a UV-transparent material for writing single Bragg gratings or arrays of chirped fiber Bragg gratings directly through the fiber coating with the use of excimer laser radiation at 248 nm. As an optimum radiation density that does not lead to significant degradation of the fluoropolymer coating, an exposure time not exceeding 200 s with a 10 Hz laser pulses repetition rate at 70 mJ/cm2 was identified. With such inscription parameters it was possible to inscribe arrays of fiber Bragg gratings in hydrogen-loaded birefringent optical fiber with an elliptical stress cladding through a 12 μm thick coating, so that stripping of the coating is avoided and good mechanical strength is preserved. The reflection spectrum width of the chirped Bragg gratings was about 3.5 nm with a reflectance coefficient of the most effective grating of up to 38%. Such Bragg grating arrays are especially interesting as reflective elements in fiber interferometers.

  14. Long Period Gratings in Random Hole Optical Fibers for Refractive Index Sensing

    Directory of Open Access Journals (Sweden)

    Gary Pickrell

    2011-01-01

    Full Text Available We have demonstrated the fabrication of long period gratings in random hole optical fibers. The long period gratings are fabricated by a point-by-point technique using a CO2 laser. The gratings with a periodicity of 450 µm are fabricated and a maximum coupling efficiency of −9.81 dB has been achieved. Sensing of different refractive indices in the surrounding mediums is demonstrated by applying standard liquids with refractive indices from 1.400 to 1.440 to the long period grating.

  15. Optical System Monitoring Based on Reflection Spectrum of Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Mastang Tanra

    2012-01-01

    Full Text Available Problem statement: This study presents fiber fault monitoring approaches for Fiber-to-the Home (FTTH with a Passive Optical Network (PON. Current fiber fault monitoring approaches are difficult to be implemented due to its complexity and high loss as the amount of branches increase. Approach: A fiber fault monitoring scheme is proposed whereas Fiber Bragg Grating (FBG is placed on each branch of the Optical Network Unit (ONU. The advantages of the scheme are that it is simple, low cost and efficient in monitoring fiber fault in ONU. FTTH based network design is simulated using Optisystemtem 8.0 in order to investigate the feasibility of the proposed scheme. Results: The reflection spectrum of Fiber Bragg Gratings (FBGs with different spectrum shape, frequencies and amplitude is used to differentiate each optical network. The simulation result shows that the unique characteristic of fiber Bragg grating is able to distinguish each optical network for a 20 km Passive Optical Network (PON system. Conclusion: This study suggests the implementation of Fiber Bragg Grating that is placed in each network instead of using Optical Time Domain Reflectometer (OTDR for fiber fault monitoring.

  16. Fabrication of advanced fiber Bragg gratings by use of sequential writing with a continuous-wave ultraviolet laser source.

    Science.gov (United States)

    Petermann, Ingemar; Sahlgren, Bengt; Helmfrid, Sten; Friberg, Ari T; Fonjallaz, Pierre-Yves

    2002-02-20

    We present a novel scheme based on sequential writing for fabrication of advanced fiber Bragg gratings. As opposed to earlier sequential methods this technique uses a cw UV laser source and allows for very precise control and repetitivity of the formation of the gratings. Furthermore it is possible to use high average irradiances without destroying the fiber, resulting in considerable reduction in fabrication time for complex gratings. The method has been applied to several test gratings, which proved its versatility and quality.

  17. 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.

  18. Monitoring of vacuum assisted resin transfer moulding (VARTM) process with superimposed Fiber-Bragg-gratings

    Science.gov (United States)

    Triollet, S.; Robert, L.; Marin, E.; Ouerdane, Y.

    2011-05-01

    We report the instrumentation of a manufacturing composite process using an optical fiber sensor based on Bragg gratings. The sensor is made of superimposed Long Period (LPG) and short period (FBG) Bragg gratings written in the same fiber section. The monitoring of the process needs simultaneous measurements of temperature and strain. It has been shown that these two solicitations can be determined and discriminated with a superimposed FBG/LPG sensor [1]. In this paper we present the device based on the dual superimposed gratings. The sensor is embedded in a composite specimen manufactured by Vacuum Assisted Resin Transfer Moulding (VARTM) process for monitoring purpose.

  19. [Measurement of steel corrosion in concrete structures by analyzing long-period fiber grating spectrum character].

    Science.gov (United States)

    Wang, Yan; Liang, Da-Kai; Zhou, Bing

    2008-11-01

    The consideration on the durability of concrete structures with reinforcement corrosion has become a most urgent problem. A new technique to measure the corrosion of steel in concrete structures was proposed in the present paper. It is based on the microbending characteristic of long period optical grating (LPFG). The temperature spectum character and curvature spectrum character of long period optical fiber grating were studied first. It was shown that the transmission spectrum of long period optical fiber grating shifted right and the transmission of the resonance wavelength was invariable when the temperature increased, while the transmission spectrum of long period optical fiber grating became shallow when the curvature increased, the transmission of the resonance wavelength would increase and it was linear with the curvature. On the basis of the characteristic, a notch shaped pedestal was designed and a long period optical fiber grating was laid on the steel surface. With this method the radial expansion of the steel resulting from the steel corrosion would translate into the curvature of the long period optical fiber grating. The curvature of long period optical fiber grating could be obtained by analyzing the change of spectrum, and then the steel corrosion depth could be measured. This method is simple and immediate and is independent of the variety in temperature, strain and refractive index owing to the inimitable spectrum characteristic of long period optical fiber grating. From the experiment it was found that the precision of the corrosion depth was better than 1.2 microm, and the corrosion depth of 3 mm could be achieved. This measurement could be used to monitor the early to metaphase corrosion of reinforcing steel in concrete structures.

  20. 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.

  1. Temperature insensitive measurements of displacement using fiber Bragg grating sensors

    Science.gov (United States)

    Yang, Shuang; Li, Jun; Xu, Shengming; Sun, Miao; Tang, Yuquan; Gao, Gang; Dong, Fengzhong

    2016-11-01

    Optical fiber Bragg grating (FBG) displacement sensors play an important role in various areas due to the high sensitivity to displacement. However, it becomes a serious problem of FBG cross-sensitivity of temperature and displacement in applications with FBG displacement sensing. This paper presents a method of temperature insensitive measurement of displacement via using an appropriate layout of the sensor. A displacement sensor is constructed with two FBGs mounted on the opposite surface of a cantilever beam. The wavelengths of the FBGs shift with a horizontal direction displacement acting on the cantilever beam. Displacement measurement can be achieved by demodulating the wavelengths difference of the two FBGs. In this case, the difference of the two FBGs' wavelengths can be taken in order to compensate for the temperature effects. Four cantilever beams with different shapes are designed and the FBG strain distribution is quite different from each other. The deformation and strain distribution of cantilever beams are simulated by using finite element analysis, which is used to optimize the layout of the FBG displacement sensor. Experimental results show that an obvious increase in the sensitivity of this change on the displacement is obtained while temperature dependence greatly reduced. A change in the wavelength can be found with the increase of displacement from 0 to 10mm for a cantilever beam. The physical size of the FBG displacement sensor head can be adjusted to meet the need of different applications, such as structure health monitoring, smart material sensing, aerospace, etc.

  2. Fiber Bragg grating photoacoustic detector for liquid chromatography.

    Science.gov (United States)

    Yang, Qingxin; Loock, Hans-Peter; Kozin, Igor; Pedersen, David

    2008-11-01

    Fiber Bragg Gratings (FBGs) are known to be sensitive acoustic transducers and have previously been used for the photoacoustic detection of small solid samples. Here, we demonstrate the use of an FBG as an on-line detector for liquid chromatography. The FBG was inserted into a silica capillary and the photoacoustic response from the effluent was generated by a 10 ns pulsed laser. The acoustic pulse was quantified by the FBG through a characteristic change in the reflection spectrum. Good repeatability and linear response were obtained over three orders of magnitude (R(2) > 0.99), and the limit of detection of Coumarin 440 was determined to be 5 microM. The technique was successfully coupled to high performance liquid chromatography and applied to on-line analysis of a three-compound solution. Photoacoustic detection in liquid chromatography using FBGs is a label-free method, which can be applied to the detection of any chromogenic compound irrespective of its fluorogenic properties. It is a simple, inexpensive, and inherently micron-sized technique, insensitive to electromagnetic interference.

  3. A non-contact fiber Bragg grating vibration sensor.

    Science.gov (United States)

    Li, Tianliang; Tan, Yuegang; Wei, Li; Zhou, Zude; Zheng, Kai; Guo, Yongxing

    2014-01-01

    A non-contact vibration sensor based on fiber Bragg grating (FBG) sensing has been proposed and studied in this paper. The principle of the sensor as well as simulation and experimental analyses are introduced. When the distance between the movable head and the measured shaft changed, the diaphragm deformed under magnetic coupling of the permanent magnet on the measured magnetic shaft. As a result, the center wavelength of the FBG connected to the diaphragm changed, based on which the vibration displacement of the rotating shaft could be obtained. Experimental results show that the resonant frequency of the sensor is about 1500 Hz and the working band ranges within 0-1300 Hz, which is consistent with the simulation analysis result; the sensitivity is -1.694 pm/μm and the linearity is 2.92% within a range of 2-2.4 mm. It can be used to conduct non-contact measurement on the vibration of the rotating shaft system.

  4. 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 to inte...

  5. Optical generation of millimeter-wave pulses using a fiber Bragg grating in a fiber-optics system.

    Science.gov (United States)

    Ye, Qing; Qu, Ronghui; Fang, Zujie

    2007-04-10

    A scheme is proposed to transform an optical pulse into a millimeter-wave frequency modulation pulse by using a weak fiber Bragg grating (FBG) in a fiber-optics system. The Fourier transformation method is used to obtain the required spectrum response function of the FBG for the Gaussian pulse, soliton pulse, and Lorenz shape pulse. On the condition of the first-order Born approximation of the weak fiber grating, the relation of the refractive index distribution and the spectrum response function of the FBG satisfies the Fourier transformation, and the corresponding refractive index distribution forms are obtained for single-frequency modulation and linear-frequency modulation millimeter-wave pulse generation. The performances of the designed fiber gratings are also studied by a numerical simulation method for a supershort pulse transmission.

  6. 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

  7. Fiber-optical microphones and accelerometers based on polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

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

    2010-01-01

    Polymer optical fibers (POFs) are ideal for applications as the sensing element in fiber-optical microphones and accelerometers based on fiber Bragg gratings (FBGs) due to their reduced Young’s Modulus of 3.2GPa, compared to 72GPa of Silica. To maximize the sensitivity and the dynamic range...... of the device the outer diameter and the length of the sensing fiber segment should be as small as possible. To this end we have fabricated 3mm FBGs in single-mode step-index POFs of diameter 115 micron, using 325nm UV writing and a phase-mask technique. 6mm POF sections with FBGs in the center have been glued...... to standard Silica SMF28 fibers. These POF FBGs have been characterized in terms of temperature and strain to find operating regimes with no hysteresis. Commercial fast wavelength interrogators (KHz) are shown to be able to track the thin POF FBGs and they are finally applied in a prototype accelerometer...

  8. Fiber-optical microphones and accelerometers based on polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

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

    2010-01-01

    Polymer optical fibers (POFs) are ideal for applications as the sensing element in fiber-optical microphones and accelerometers based on fiber Bragg gratings (FBGs) due to their reduced Young’s Modulus of 3.2GPa, compared to 72GPa of Silica. To maximize the sensitivity and the dynamic range...... of the device the outer diameter and the length of the sensing fiber segment should be as small as possible. To this end we have fabricated 3mm FBGs in single-mode step-index POFs of diameter 115 micron, using 325nm UV writing and a phase-mask technique. 6mm POF sections with FBGs in the center have been glued...... to standard Silica SMF28 fibers. These POF FBGs have been characterized in terms of temperature and strain to find operating regimes with no hysteresis. Commercial fast wavelength interrogators (KHz) are shown to be able to track the thin POF FBGs and they are finally applied in a prototype accelerometer...

  9. Wide wavelength-tuning of a double-clad Yb3+-doped fiber laser based on a fiber Bragg grating array

    NARCIS (Netherlands)

    Alvarez-Chavez, J.A.; Martinez-Rios, A.; Torres-Gomez, I.; Offerhaus, H.L.

    2007-01-01

    We report wide wavelength tuning in a double-clad ytterbium-doped fiber laser. The laser cavity consists of an array of broadband high-reflection fiber Bragg gratings and a bulk grating as output coupler and wavelength selection element. The proposed fiber laser configuration combines low intra-cavi

  10. 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.

  11. Tilted fiber Bragg gratings in multicore optical fibers for optical sensing.

    Science.gov (United States)

    Barrera, David; Madrigal, Javier; Sales, Salvador

    2017-04-01

    We have inscribed a tilted fiber Bragg grating (TFBG) in selected cores of a multicore optical fiber. The presence of the TFBG permits to couple light from the incident-guided mode to the cladding modes and to the neighbor cores, and this interaction can be used for optical sensing. We measured different magnitudes: strain, curvature magnitude and direction, and external refractive index. The curvature results show a linear dependence of the maximum crosstalk with the curvature magnitude with a sensitivity of 2.5  dB/m-1 as the curvature magnitude increases and at the same time a wavelength shift of 70  pm/m-1. Changes in the external refractive index gradually vanish the cladding modes resonances and the crosstalk between the different cores, obtaining a reduction of the 90% of the optical spectra integral area for refractive indexes between 1.398 and 1.474.

  12. Sensitivity of photonic crystal fiber grating sensors: biosensing, refractive index, strain, and temperature sensing

    DEFF Research Database (Denmark)

    Rindorf, Lars Henning; Bang, Ole

    2008-01-01

    We study the sensitivity of fiber grating sensors in the applications of strain, temperature, internal label-free biosensing, and internal refractive index sensing. New analytical expressions for the sensitivities, valid for photonic crystal fibers are rigorously derived. These are generally valid...

  13. 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.

  14. Design and UV writing of advanced Bragg gratings in optical fibers

    DEFF Research Database (Denmark)

    Plougmann, Nikolai

    2004-01-01

    The refractive index of germano-silica glasses changes during exposure to ultraviolet light. Illuminating an optical fiber with a UV laser, it is possible to induce a periodic change in the effective refractive index of the fiber (Bragg grating). Two main contributions of the Ph.D. project...

  15. 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

  16. 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...

  17. Optical fiber grating based technologies and their applications: from nuclear fusion to medical

    NARCIS (Netherlands)

    Cheng, L.K.; Vliegenhart, W.A.; Habisreuther, T.

    2012-01-01

    In the last decades, Fiber Optic (FO) sensor has gained increasing acceptance. Among the different FO sensor types, Fiber Bragg Grating is most widely used due to its commercial availability and the unique multiplexing potential. The latter feature enables the development of large sensor array and/o

  18. An analysis of As2S3 chirped fiber grating formed by two-photon absorption effect

    Institute of Scientific and Technical Information of China (English)

    Huaisheng Wang(王淮生); Zhigang Zhang(张志刚); Lu Chai(柴路); Qingyue Wang(王清月)

    2003-01-01

    When femtosecond laser pulses interfere with chirped femtosecond laser pulses in As2S3 fiber, a chirped fiber grating is formed. An analytical expression is given to describe the chirped grating, and its Bragg reflectivity is calculated. Because of the high photosensitive effect of As2S3 material, the chirped fiber grating has a wide Bragg reflective spectrum and high reflectivity by choosing proper parameters. This indicates that the chirped fiber grating can be used as a stretcher in the femtosecond chirped pulse amplification (CPA) system.

  19. Novel measurement scheme of peak separation of side-hole fiber grating

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-zhong; SUN Chong-feng; CAO Chun-yan; YANG Hua-yong; HU Yong-ming

    2006-01-01

    There are two peaks of different polarizations in the reflection spectrum of the side-hole fiber grating and their separation interval has a linear variation along with the pressure changing while it is insensitive to the temperature.We have proposed a novel measurement scheme based on polarization detection.The detection of peak separation is achieved by measuring the two peaks' center wavelengths separately with all polarization maintaining fiber system.The side-hole fiber grating pressure sensing within the range of 0~3.5 MPa is realized successfully with the new scheme.

  20. Polymer optical fiber Bragg grating inscription with a single UV laser pulse

    DEFF Research Database (Denmark)

    Pospori, Andreas; Marques, A.T.; Bang, Ole

    2017-01-01

    We experimentally demonstrate the first polymer optical fiber Bragg grating inscribed with only one krypton fluoride laser pulse. The device has been recorded in a single-mode poly(methyl methacrylate) optical fiber, with a core doped with benzyl dimethyl ketal for photosensitivity enhancement. One...... laser pulse with a duration of 15 ns, which provide energy density of 974 mJ/cm2, is adequate to introduce a refractive index change of 0.74×10-4 in the fiber core. After the exposure, the reflectivity of the grating increases for a few minutes following a second order exponential saturation...

  1. Silicon grating structures for optical fiber interfacing and III-V/silicon opto-electronic components

    Science.gov (United States)

    Roelkens, Gunther; Vermeulen, Diedrik; Li, Yanlu; Muneeb, Muhammad; Hattasan, Nannicha; Ryckeboer, Eva; Deconinck, Yannick; Van Thourhout, Dries; Baets, Roel

    2013-02-01

    In this paper, we review our work on efficient, broadband and polarization independent interfaces between a silicon-on-insulator photonic IC and a single-mode optical fiber based on grating structures. The high alignment tolerance and the fact that the optical fiber interface is out-of-plane provide opportunities for easy packaging and wafer-scale testing of the photonic IC. Next to fiber-chip interfaces we will discuss the use of silicon grating structures in III-V on silicon optoelectronic components such as integrated photodetectors and microlasers.

  2. Bare Fiber Bragg Gratings embedded into concrete buffer Supercontainer concept for nuclear waste storage

    Energy Technology Data Exchange (ETDEWEB)

    Kinet, Damien; Chah, Karima; Megret, Patrice; Caucheteur, Christophe [Electromagnetism and Telecommunications Department of the University of Mons, 31 Boulevard Dolez, 7000 Mons, (Belgium); Gusarov, Andrei [Belgian Nuclear Research Center, Boeretang 200, 2400 Mol, (Belgium); Faustov, Alexey [Belgian Nuclear Research Center, Boeretang 200, 2400 Mol, (Belgium); Electromagnetisme and Telecommunication Department of the University of Mons, 31 Boulevard Dolez, 7000 Mons, (Belgium); Areias, Lou [Mechanics of Materials and Constructions Department of the Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, (Belgium); European Underground Research Infrastructure for Disposal of nuclear waste In Clay Environment, Boeretang 200, 2400 Mol, (Belgium)

    2015-07-01

    We present the preliminary results obtained with bare fiber Bragg grating-based sensors embedded into half-scale Belgian Supercontainer concept. Being temperature and strain sensitive, some sensors were placed into aluminum tubes to monitor only temperature and results were compared with thermocouples data. The utility of using bare fiber Bragg gratings, knowing that these ones are very fragile, is to have a direct contact between the high alkaline environment of the concrete and silica fibers and to determine its impact over a very long time. (authors)

  3. Cross-sensitivity of Fiber Grating Solved by FFP Triangle Notch Filter

    Institute of Scientific and Technical Information of China (English)

    GONG Xian-feng; WANG Chang-song; CHEN Sheng-ping; LI Jia-fang

    2004-01-01

    Employing a fiber Fabry-Perot (FFP) interferometer has been considered as a triangle notch filter to demodulate the wavelength of fiber Bragg grating (FBG) sensor.The single parameter of strain has been demodulated,and the cross-sensitivity influence of temperature has been eliminated.The principle of this method is simple and easy to be implemented,and has been used to design a 30 t fiber grating weightbridge successfully.The maximal temperature drift error of the weightbridge is 4 με,which means that the full scale error is 8‰. The result reveals that the accuracy is high enough to be used in measurement.

  4. Dispersion compensation of fiber Bragg gratings in 3100 km high speed optical fiber transmission system

    Institute of Scientific and Technical Information of China (English)

    Li PEI; Tigang NING; Fengping YAN; Xiaowei DONG; Zhongwei TAN; Yan LIU; Shuisheng JIAN

    2009-01-01

    By optimizing the fabrication process of the chirped optical fiber Bragg grating (CFBG), some key problems of CFBG are solved, such as fabrication repetition, temperature stability, group delay ripple (GDR), fluctuation of the reflection spectrum, polarization mode dispersion (PMD), interaction of cascaded CFBG, and so on. The CFBG we fabricated can attain a temperature coefficient less than 0.0005 nm/℃, and the smoothed GDR and the fluctuation of the reflection spectrum are smaller than 10ps and 0.5dB, respec-tively. The PMD of each CFBG is less than 1 ps and the dispersion of each grating is larger than -2600 ps/(nm·km). With dispersion compensated by the CFBGs we fabricated, a 13×10 Gbit/s 3100 km ultra long G.652 fiber transmission system is successfully imple-mented without electric regenerator. The bit error rate (BER) of the system is below 10-4 without forward error correction (FEC); when FEC is added, the BER is below 10-12. The power penalty of the carrier-suppressed return-to-zero (CSRZ) code transmission system is only 2.5 dB.

  5. Noise in adaptive interferometric fiber sensor based on population dynamic grating in erbium-doped fiber.

    Science.gov (United States)

    Stepanov, Serguei; Sánchez, Marcos Plata; Hernández, Eliseo Hernández

    2016-09-10

    Experimental investigations of the main noise sources that limit the sensitivity of the adaptive interferometric all-fiber sensors operating in the communication wavelength region are reported. Adaptive properties (i.e., the autostabilization of an optimal operation point of the interferometer) are enabled by the dynamic population grating recorded in a segment of the erbium-doped fiber (EDF) at milliwatt-scale cw power in the 1480-1560 nm spectral range. The utilized symmetric Sagnac configuration with low light internal reflections ensures reduced sensitivity of the sensor to phase noise of the laser, while intensity noise is reduced to an insignificant level by the balanced detection scheme. It is shown that the fluorescence from the erbium ions, excited by the counterpropagating waves recording the grating, increases the noise level from the fundamental shot noise approximately by a factor of 2-3 only. It is also shown that conventional communication distributed feedback (DFB) semiconductor lasers with megahertz linewidth are not suitable for high-sensitivity applications of such sensors. Because of inevitable backreflections from the output terminal devices (photodiodes, insulators, circulator), the above-mentioned fundamental noise level is increased by 2 orders of magnitude due to high phase noise of the DFB laser.

  6. Fiber Bragg Grating Sensors for the Oil Industry

    Science.gov (United States)

    Qiao, Xueguang; Shao, Zhihua; Bao, Weijia; Rong, Qiangzhou

    2017-01-01

    With the oil and gas industry growing rapidly, increasing the yield and profit require advances in technology for cost-effective production in key areas of reservoir exploration and in oil-well production-management. In this paper we review our group’s research into fiber Bragg gratings (FBGs) and their applications in the oil industry, especially in the well-logging field. FBG sensors used for seismic exploration in the oil and gas industry need to be capable of measuring multiple physical parameters such as temperature, pressure, and acoustic waves in a hostile environment. This application requires that the FBG sensors display high sensitivity over the broad vibration frequency range of 5 Hz to 2.5 kHz, which contains the important geological information. We report the incorporation of mechanical transducers in the FBG sensors to enable enhance the sensors’ amplitude and frequency response. Whenever the FBG sensors are working within a well, they must withstand high temperatures and high pressures, up to 175 °C and 40 Mpa or more. We use femtosecond laser side-illumination to ensure that the FBGs themselves have the high temperature resistance up to 1100 °C. Using FBG sensors combined with suitable metal transducers, we have experimentally realized high- temperature and pressure measurements up to 400 °C and 100 Mpa. We introduce a novel technology of ultrasonic imaging of seismic physical models using FBG sensors, which is superior to conventional seismic exploration methods. Compared with piezoelectric transducers, FBG ultrasonic sensors demonstrate superior sensitivity, more compact structure, improved spatial resolution, high stability and immunity to electromagnetic interference (EMI). In the last section, we present a case study of a well-logging field to demonstrate the utility of FBG sensors in the oil and gas industry. PMID:28241460

  7. 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.

  8. Multiplex and simultaneous measurement of displacement and temperature using tapered fiber and fiber Bragg grating

    Energy Technology Data Exchange (ETDEWEB)

    Ji Chongke; Zhao Chunliu; Kang Juan; Dong Xinyong; Jin Shangzhong [Institute of Optoelectronic Technology, China Jiliang University, Hangzhou 310018 (China)

    2012-05-15

    A simple method to work out the multiplexing of tapered fiber based sensors is proposed and demonstrated. By cascading a tapered fiber with a fiber Bragg grating (FBG), the sensor head is provided with a wavelength identification, different FBGs provide the sensor heads with different reflective peaks and they can be distinguished in optical spectrum. By compositing several such sensor heads with a multi-channel beam splitter, a star-style topological structure sensor for multipoint sensing is achieved. At the same time, the output intensity at the peak wavelength is sensitive to one external physical parameter applied on the related FBG-cascaded tapered fiber and the central wavelength of the peak is only sensitive to temperature, so that that parameter and temperature can be measured simultaneously. A sensor for dual-point measurement of the displacement and temperature simultaneously is experimentally demonstrated by using a 2 x 2 coupler in this paper. Experiment results show that the sensor works well and the largest sensitivities reach to 0.11 dB/{mu}m for displacement in the range of 0-400 {mu}m, and {approx}0.0097 nm/ deg. C for temperature between 20 deg. C and 70 deg. C.

  9. Experimental investigation of the thin fiber-optic hydrophone array based on fiber Bragg gratings

    Science.gov (United States)

    Lavrov, Vladimir S.; Plotnikov, Mikhail Y.; Aksarin, Stanislav M.; Efimov, Mikhail E.; Shulepov, Vladimir A.; Kulikov, Andrey V.; Kireenkov, Alexander U.

    2017-03-01

    The paper presents the results of experimental investigations of the fiber optic hydrophone array consisting of six sensors, placed in one thin sensitive cable. Sensors were formed by pairs of Bragg gratings spaced 1.5 m apart and recorded in a birefringent optical fiber with the elliptical stressed coating. To form an extended sensor array the optical fiber was additionally covered with a silicone material RTV655 and protective coatings. Experimental investigations of the array showed that fiber-optic sensors pressure sensitivity increases as the acoustic frequency decreases at average value from -169.4 dB re rad/uPa at 495 Hz to -143.7 dB re rad/uPa at 40 Hz. The minimum detectable pressure was at average value from 53 mPa/√Hz at 495 Hz to 8.3 mPa/√Hz at 40 Hz. The obtained results might be used for developing and producing long thin hydroacoustic arrays for geophysical investigations and other hydroacoustic applications.

  10. Capturing reflected cladding modes from a fiber Bragg grating with a double-clad fiber coupler.

    Science.gov (United States)

    Baiad, Mohamad Diaa; Gagné, Mathieu; Lemire-Renaud, Simon; De Montigny, Etienne; Madore, Wendy-Julie; Godbout, Nicolas; Boudoux, Caroline; Kashyap, Raman

    2013-03-25

    We present a novel measurement scheme using a double-clad fiber coupler (DCFC) and a fiber Bragg grating (FBG) to resolve cladding modes. Direct measurement of the optical spectra and power in the cladding modes is obtained through the use of a specially designed DCFC spliced to a highly reflective FBG written into slightly etched standard photosensitive single mode fiber to match the inner cladding diameter of the DCFC. The DCFC is made by tapering and fusing two double-clad fibers (DCF) together. The device is capable of capturing backward propagating low and high order cladding modes simply and efficiently. Also, we demonstrate the capability of such a device to measure the surrounding refractive index (SRI) with an extremely high sensitivity of 69.769 ± 0.035 μW/RIU and a resolution of 1.433 × 10(-5) ± 8 × 10(-9) RIU between 1.37 and 1.45 RIU. The device provides a large SRI operating range from 1.30 to 1.45 RIU with sufficient discrimination for all individual captured cladding modes. The proposed scheme can be adapted to many different types of bend, temperature, refractive index and other evanescent wave based sensors.

  11. Reproducibility of splicer-based long-period fiber gratings for gain equalization

    Institute of Scientific and Technical Information of China (English)

    I. Cacciari; M. Brenci; R. Falclai; G. Nunzi Conti; S. Pelli; G. C. Righini

    2007-01-01

    We fabricated long-period fiber gratings (LPFGs) using electric arc discharges. We observed that the fiber becomes slightly tapered due to longitudinal tension during the arc: this effect depends on the arc current and time length. We experimentally investigated how these characteristics can influence grating' s performances, especially in view of employing the LPFG as gain equalizer for an erbium-doped optical amplifier. As expected, we found that the spectral response of the grating depends on the period A, the intensity of the perturbation, the grating length and the type of mode-coupling induced. Since this last parameter cannot be estimated directly from the transmission spectra, we propose a method to determine the modecoupling occurring in the device and to assess the index modulation induced by the electric arcs. This method combines both experimental and simulated data, and can be used to characterize LPFGs made-up by any method.

  12. Theoretical and experimental investigation of fiber Bragg gratings with different lengths for ultrasonic detection

    Science.gov (United States)

    Yu, Zhouzhou; Jiang, Qi; Zhang, Hao; Wang, Junjie

    2016-06-01

    In this paper, the response of fiber Bragg gratings (FBGs) subjected to the ultrasonic wave has been theoretically and experimentally investigated. Although FBG sensors have been widely used in the ultrasonic detection for practical structural health monitoring, the relationship between the grating length and ultrasonic frequency is not yet to be obtained. To address this problem, an ultrasound detection system based on FBGs is designed and the response sensitivity of different lengths gratings are detected. Experimental results indicate that the grating with 3 mm length has a higher sensitivity when detecting high frequency ultrasonic wave, and the amplitude can be up to 0.6 mV. The 10 mm length grating has better detection sensitivity for low frequency ultrasonic wave and the amplitude is 0.8 mV. The results of this analysis provide useful tools for high sensitivity ultrasound detection in damage detection systems.

  13. Inverse-Gaussian-Apodized Fiber Bragg Grating for Dual Wavelength Lasing

    CERN Document Server

    Lin, Bo; Tjin, Swee Chuan; Tang, Dingyuan; Hao, Jianzhong; Tay, Chia Meng; Liang, Sheng

    2010-01-01

    A fiber Bragg grating (FBG) with an inverse-Gaussian apodization function is proposed and fabricated. It is shown that such a FBG possesses easily controllable dual-wavelength narrow transmission peaks. Incorporating such a FBG filter in a fiber laser with a linear cavity, stable dual-wavelength emission with 0.146 nm wavelength spacing is obtained. It provides a simple and low cost approach of achieving the dual-wavelength fiber laser operation.

  14. Development of Interpretation Algorithm for Optical Fiber Bragg Grating Sensors for Composite Structures

    Science.gov (United States)

    Peters, Kara

    2002-12-01

    Increasingly, optical fiber sensors, and in particular Bragg grating sensors, are being used in aerospace structures due to their immunity to electrical noise and the ability to multiplex hundreds of sensors into a single optical fiber. This significantly reduces the cost per sensor as the number of fiber connections and demodulation systems required is also reduced. The primary objective of this project is to study the effects of mounting issues such as adhesion, surface roughness, and high strain gradients on the interpretation of the measured strain. This is performed through comparison with electrical strain gage benchmark data. The long-term goal is to integrate such optical fiber Bragg grating sensors into a structural integrity monitoring system for the 2nd Generation Reusable Launch Vehicle. Previously, researchers at NASA Langley instrumented a composite wingbox with both optical fiber Bragg grating sensors and electrical strain gages during laboratory load-to-failure testing. A considerable amount of data was collected during these tests. For this project, data from two of the sensing optical fibers (each containing 800 Bragg grating sensors) were analyzed in detail. The first fiber studied was mounted in a straight line on the upper surface of the wingbox far from any structural irregularities. The results from these sensors showed a relatively large amount of noise compared to the electrical strain gages, but measured the same averaged strain curve. It was shown that the noise could be varied through the choice of input parameters in the data interpretation algorithm. Based upon the assumption that the strain remains constant along the gage length (a valid assumption for this fiber as confirmed by the measured grating spectra) this noise was significantly reduced. The second fiber was mounted on the lower surface of the wingbox in a pattern that circled surface cutouts and ran close to sites of impact damage, induced before the loading tests. As

  15. 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.

  16. Tunable Microwave Photonic Notch Filter Based on a high-birefringence linearly chirped fiber Bragg grating

    Energy Technology Data Exchange (ETDEWEB)

    Jin Yongxing; Dong Xinyong; Wang Jianfeng [Institute of Optoelectronic Technology, China Jiliang University, Hangzhou (China); Zhou Junqiang, E-mail: phyjyxin@gmail.com [Network Technology Research Centre, Nanyang Technological University (Singapore)

    2011-02-01

    In this paper, a continuously tunable microwave photonic notch filter is proposed and experimentally demonstrated. This filter is based on the differential group delay generated by a high-birefringence linearly chirped fiber Bragg grating. This microwave photonic filter belongs to the orthogonal polarization approach, polarization maintaining structure ensures the filter free from the random optical interference problem. Its response is induced by the differential group delay (DGD) of the Hi-Bi LCFBG and it can be varied by tuning the grating through adding gradient strength to the grating. Free spectral range tuning by 9.27 GHz with more than 35 dB notch rejection is achieved.

  17. Recent developments of Bragg gratings in PMMA and TOPAS polymer optical fibers

    DEFF Research Database (Denmark)

    Webb, David; Kyriacos, Kalli; Carroll, Karen

    We report on the temperature response of FBGs recorded in pure PMMA and TOPAS holey fibers. The gratings are fabricated in the near IR using a cw He-Cd laser operating at 325nm. The room temperature grating response is non-linear and characterised by quadratic behaviour for temperatures from room......, leading to very good fibre drawing properties. Furthermore, although Topas is chemically inert and biomolecules do not readily bind to its surface, treatment with Antraquinon and subsequent UV activation allows sensing molecules to be deposited in well defined spatial locations. When combined with grating...

  18. Femtosecond direct-writing of low-loss fiber Bragg gratings using a continuous core-scanning technique.

    Science.gov (United States)

    Williams, Robert J; Krämer, Ria G; Nolte, Stefan; Withford, Michael J

    2013-06-01

    We report the inscription of low-loss fiber Bragg gratings using focused femtosecond (fs) pulses and a continuous core-scanning technique. This direct-write technique produces high-fidelity Type I-IR gratings that share the inherent advantages of other direct-write methods, such as the point-by-point (PbP) method, for which the grating period is a free parameter. However, here we demonstrate an order of magnitude improvement in scattering loss compared to PbP gratings, to a level comparable with that of phase-mask-based fs inscription. A first-order grating was inscribed in standard telecommunications fiber with -49 dB transmission at the Bragg wavelength and 0.1 dB broadband scattering loss. Potential application of these gratings to large-mode-area fibers and chirped grating fabrication are highlighted.

  19. Study of sensing properties and contrastive analysis of metal coating optical fiber grating

    Science.gov (United States)

    Wang, Jing; Wang, Ning; Shi, Bin; Sui, Qingmei; Guan, Congsheng; Wei, Guangqing; Li, Shuhua

    2014-02-01

    Optical fiber grating (FBG) has been widely used in the measurement of parameters such as temperature and strain. However, FBG is too slim to broken, whose outside protective layer tends to shedding easily, and it is also hard to change the temperature and strain sensitivity. In order to overcome the above disadvantages and to further expand the application range of FBG, this paper improves the technology of fiber grating metal film plating process firstly. It adopts a compositive method including chemical plating and electroplating to gild FBG, copper FBG and galvanize FBG, which all get good metal coating. Then, the temperature and strain sensing properties of metalized FBG is studied in detail. Multiple metal coating FBGs were put in high-low temperature test-box together, and then the test-box worked continuously at the temperature range of 0°C~95°C. After several experiments, it concludes that metal plating enhances the temperature sensitivity of fiber grating, and the one with galvanization has the highest temperature sensitivity of 0.0235. At last, FBGs with various cladding were pasted on carbon fiber cantilever beam respectively and the pressure on the top of the cantilever increased gradually. The experimental results show that wavelength of fiber grating shift toward the long wavelength with the increase of the pressure, and the one with galvanization has the maximum strain sensitivity which has minimal impact on fiber properties.

  20. Design and analysis of spectral beam combining system for fiber lasers based on a concave grating

    Institute of Scientific and Technical Information of China (English)

    WU Zhuo-liang; ZHAO Shang-hong; CHU Xing-chun; ZHANG Xi; ZHAN Sheng-bao; MA Li-hua

    2012-01-01

    Anovel fiber laser spectral beam combining scheme based on a concave grating is presented.The principle of the presented system is analyzed,and a concave grating with blazed structure for spectral beam combining is designed.The combining potential of the system is analyzed,and the results show that 39 Yb-doped fiber laser can be spectrally beam combined via the designed system.By using scalar diffraction theory,the combining effect of the system is analyzed.The results show that the diffraction efficiency of the designed concave grating is higher than 72% over the whole gain bandwidth,and the combining efficiency is 73.4%.With output power of 1 kW for individual fiber laser,combined power of 28.6 kW can be achieved.

  1. Highly sensitive fiber grating chemical sensors: An effective alternative to atomic absorption spectroscopy

    Science.gov (United States)

    Laxmeshwar, Lata. S.; Jadhav, Mangesh S.; Akki, Jyoti. F.; Raikar, Prasad; Kumar, Jitendra; prakash, Om; Raikar, U. S.

    2017-06-01

    Accuracy in quantitative determination of trace elements like Zinc, present in drinking water in ppm level, is a big challenge and optical fiber gratings as chemical sensors may provide a promising solution to overcome the same. This paper presents design of two simple chemical sensors based on the principle of shift in characteristic wavelength of gratings with change in their effective refractive index, to measure the concentration of Zinc in drinking water using etched short period grating (FBG) and Long period grating (LPG) respectively. Three samples of drinking water from different places have been examined for presence of Zinc. Further, the results obtained by our sensors have also been verified with the results obtained by a standard method, Atomic absorption spectroscopy (AAS). The whole experiment has been performed by fixing the fibers in a horizontal position with the sensor regions at the center of the fibers, making it less prone to disturbance and breaking. The sensitivity of LPG sensor is about 205 times that of the FBG sensor. A few advantages of Fiber grating sensors, besides their regular features, over AAS have also been discussed, that make our sensors potential alternatives for existing techniques in determination of trace elements in drinking water.

  2. Distributed light delivery and detection via single optical fiber and tilted grating

    Science.gov (United States)

    Pashaie, Ramin

    2014-03-01

    A passive fiber-optic-based device is designed and analyzed, capable of delivering and detecting light separately or simultaneously at discrete points of interest along the optical axis of a fiber. This goal is achieved by implementation of multiple finite-length tilted gratings inside the core of a single-mode fiber. Each grating is tuned to function as a leaky electromagnetic resonator that resonates at particular wavelength and partially radiates the optical power to the medium surrounding the fiber. First, the basic element of such radiators is theoretically analyzed and a sequence of justifiable approximations are presented to measure the characteristic parameters of the system. Next, a set of equations are developed to provide a logical procedure for the design. This device has several potential applications in the field of fiber optic sensors. Few practical examples of such applications, particularly for optical stimulation of cells and fluorescence signal recording in sensitive tissues including the brain, are studied.

  3. Adaptive ultrasonic sensor using a fiber ring laser with tandem fiber Bragg gratings.

    Science.gov (United States)

    Liu, Tongqing; Hu, Lingling; Han, Ming

    2014-08-01

    We propose and demonstrate an intensity-demodulated fiber-optic ultrasonic sensor system that can be self-adaptive to large quasi-static background strain perturbations. The sensor system is based on a fiber ring laser (FRL) whose laser cavity includes a pair of fiber Bragg gratings (FBGs). Self-adaptive ultrasonic detection is achieved by a tandem design where the two FBGs are engineered to have differential spectral responses to ultrasonic waves and are installed side-by-side at the same location on a structure. As a result, ultrasonic waves lead to relative spectral shifts of the FBGs and modulations to the cold-cavity loss of the FRL. Ultrasonic waves can then be detected directly from the laser intensity variations in response to the cold-cavity loss modulation. The sensor system is insensitive to quasi-static background strains because they lead to identical responses of the tandem FBGs. Based on the principle, a FRL sensor system was demonstrated and tested for adaptive ultrasonic detection when large static strains as well as dynamic sinusoidal vibrations were applied to the sensor.

  4. Embedded optical fiber Bragg grating sensors for the measurement of crack-bridging forces in composites

    Science.gov (United States)

    Studer, Michel; Peters, Kara J.; Botsis, John

    2002-07-01

    Fiber reinforced composites offer increased resistance to fracture as compared to isotropic materials. In addition, they have demonstrated great potential to support embedded sensor systems. However, to develop a truly reliable, embedded sensor for composites, the failure modes of such materials, including the influence of the embedded fiber sensor, must be known. Crack bridging by intact fibers is considered to be one of the most efficient mechanisms to slow down transverse crack propagation in a fiber reinforced composite. This paper presents non-invasive, direct measurements of bridging fiber stresses in a model epoxy/glass composite, using long gage length optical fiber Bragg gratings. Several central crack specimens, containing artificially bridged cracks, were fabricated and tested. The Bragg grating gage length of 12 mm permitted measurement of the force distribution in the reinforcing fiber extending from the crack surface to the far field region. A T-matrix simulation was used to model the grating response. Results from specimens involving both a strong and mixed interface are presented. The measured strain distribution in the bridging fibers compared well with previous analytical models. Discussion of the application of these results to structurally embedded sensors for damage detection is also presented.

  5. Fiber grating sensor demodulation technique using a linear array of photodetectors

    Science.gov (United States)

    Jun, Tao; Lei, Mu; Ping, Du

    2008-12-01

    The article describes the theory, characters and performance of the linear array of photodetectors includes CCD, PDA, CMOS and InGaAs, presents fiber grating sensor demodulation technique using linear InGaAs array and designs the demodulation system based on this technique. Furthermore, the system is used to measure the strain and temperature respectively, and prove the system have a good practicability. The demodulation system has a high resolution and measurement precision, changes the size of traditional Fiber Grating Sensors demodulation system essentially, and realizes basically the intelligence of the FBG sensors and lays a foundation for the industrialization of the FBG sensors.

  6. Proof of concept of impact detection in composites using fiber bragg grating arrays.

    Science.gov (United States)

    Gomez, Javier; Jorge, Iagoba; Durana, Gaizka; Arrue, Jon; Zubia, Joseba; Aranguren, Gerardo; Montero, Ander; López, Ion

    2013-09-09

    Impact detection in aeronautical structures allows predicting their future reliability and performance. An impact can produce microscopic fissures that could evolve into fractures or even the total collapse of the structure, so it is important to know the location and severity of each impact. For this purpose, optical fibers with Bragg gratings are used to analyze each impact and the vibrations generated by them. In this paper it is proven that optical fibers with Bragg gratings can be used to detect impacts, and also that a high-frequency interrogator is necessary to collect valuable information about the impacts. The use of two interrogators constitutes the main novelty of this paper.

  7. Temperature field measurement of spindle ball bearing under radial force based on fiber Bragg grating sensors

    Directory of Open Access Journals (Sweden)

    Yanfang Dong

    2015-12-01

    Full Text Available Bearing temperature rise amplitude is related to the running state of bearing and spindle thermal error, so the measurement of bearing temperature field is helpful to ascertain the bearing running characteristic and analysis of the spindle thermal error. On the basis of thoroughly understood several reasons of bearing heat generation, this article analyzes bearing temperature field simulation based on ANSYS and bearing temperature field measurement based on fiber Bragg grating sensors. The results showed that using fiber Bragg grating is able to complete the bearing temperature field distribution measurement perfectly.

  8. Sensitivity of a long-period optical fiber grating bend sensor

    DEFF Research Database (Denmark)

    Rathje, Jacob; Svalgaard, Mikael; Hübner, Jörg

    1998-01-01

    We have investigated the sensitivity of long-period fiber gratings used in curvature measuring fibre optic sensors and found a bend coefficient of 0.77 dB cm/mrad. In the current setup this corresponds to the ability of detecting curvatures with a radius up to approximately 200 m......We have investigated the sensitivity of long-period fiber gratings used in curvature measuring fibre optic sensors and found a bend coefficient of 0.77 dB cm/mrad. In the current setup this corresponds to the ability of detecting curvatures with a radius up to approximately 200 m...

  9. 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.

  10. 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.

  11. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    May A, M.; Kuzin, E.A.; Vazquez S, R.A. [Instituto Nacional de Astrofisica, Optica y Electronica, A. P. 51 y 216, C.P. 72000 Puebla (Mexico); Basurto P, M.A. [Universidad Autonoma del Estado de Morelos, Av. Universidad No. 1001, Col. Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico); Shlyagin, M.G.; Marquez B, I. [Centro de Investigacion Cientifica y de Ensenanza Superior de Ensenada, C.P. 22860 Ensenada, Baja California (Mexico)

    2002-07-01

    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)

  13. 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.

  14. 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.

  15. Suspended mid-infrared fiber-to-chip grating couplers for SiGe waveguides

    Science.gov (United States)

    Favreau, Julien; Durantin, Cédric; Fédéli, Jean-Marc; Boutami, Salim; Duan, Guang-Hua

    2016-03-01

    Silicon photonics has taken great importance owing to the applications in optical communications, ranging from short reach to long haul. Originally dedicated to telecom wavelengths, silicon photonics is heading toward circuits handling with a broader spectrum, especially in the short and mid-infrared (MIR) range. This trend is due to potential applications in chemical sensing, spectroscopy and defense in the 2-10 μm range. We previously reported the development of a MIR photonic platform based on buried SiGe/Si waveguide with propagation losses between 1 and 2 dB/cm. However the low index contrast of the platform makes the design of efficient grating couplers very challenging. In order to achieve a high fiber-to-chip efficiency, we propose a novel grating coupler structure, in which the grating is locally suspended in air. The grating has been designed with a FDTD software. To achieve high efficiency, suspended structure thicknesses have been jointly optimized with the grating parameters, namely the fill factor, the period and the grating etch depth. Using the Efficient Global Optimization (EGO) method we obtained a configuration where the fiber-to-waveguide efficiency is above 57 %. Moreover the optical transition between the suspended and the buried SiGe waveguide has been carefully designed by using an Eigenmode Expansion software. Transition efficiency as high as 86 % is achieved.

  16. Spatial Division Multiplexed Microwave Signal processing by selective grating inscription in homogeneous multicore fibers

    Science.gov (United States)

    Gasulla, Ivana; Barrera, David; Hervás, Javier; Sales, Salvador

    2017-01-01

    The use of Spatial Division Multiplexing for Microwave Photonics signal processing is proposed and experimentally demonstrated, for the first time to our knowledge, based on the selective inscription of Bragg gratings in homogeneous multicore fibers. The fabricated devices behave as sampled true time delay elements for radiofrequency signals offering a wide range of operation possibilities within the same optical fiber. The key to processing flexibility comes from the implementation of novel multi-cavity configurations by inscribing a variety of different fiber Bragg gratings along the different cores of a 7-core fiber. This entails the development of the first fabrication method to inscribe high-quality gratings characterized by arbitrary frequency spectra and located in arbitrary longitudinal positions along the individual cores of a multicore fiber. Our work opens the way towards the development of unique compact fiber-based solutions that enable the implementation of a wide variety of 2D (spatial and wavelength diversity) signal processing functionalities that will be key in future fiber-wireless communications scenarios. We envisage that Microwave Photonics systems and networks will benefit from this technology in terms of compactness, operation versatility and performance stability.

  17. Spatial Division Multiplexed Microwave Signal processing by selective grating inscription in homogeneous multicore fibers

    Science.gov (United States)

    Gasulla, Ivana; Barrera, David; Hervás, Javier; Sales, Salvador

    2017-01-01

    The use of Spatial Division Multiplexing for Microwave Photonics signal processing is proposed and experimentally demonstrated, for the first time to our knowledge, based on the selective inscription of Bragg gratings in homogeneous multicore fibers. The fabricated devices behave as sampled true time delay elements for radiofrequency signals offering a wide range of operation possibilities within the same optical fiber. The key to processing flexibility comes from the implementation of novel multi-cavity configurations by inscribing a variety of different fiber Bragg gratings along the different cores of a 7-core fiber. This entails the development of the first fabrication method to inscribe high-quality gratings characterized by arbitrary frequency spectra and located in arbitrary longitudinal positions along the individual cores of a multicore fiber. Our work opens the way towards the development of unique compact fiber-based solutions that enable the implementation of a wide variety of 2D (spatial and wavelength diversity) signal processing functionalities that will be key in future fiber-wireless communications scenarios. We envisage that Microwave Photonics systems and networks will benefit from this technology in terms of compactness, operation versatility and performance stability. PMID:28134304

  18. Spatial Division Multiplexed Microwave Signal processing by selective grating inscription in homogeneous multicore fibers.

    Science.gov (United States)

    Gasulla, Ivana; Barrera, David; Hervás, Javier; Sales, Salvador

    2017-01-30

    The use of Spatial Division Multiplexing for Microwave Photonics signal processing is proposed and experimentally demonstrated, for the first time to our knowledge, based on the selective inscription of Bragg gratings in homogeneous multicore fibers. The fabricated devices behave as sampled true time delay elements for radiofrequency signals offering a wide range of operation possibilities within the same optical fiber. The key to processing flexibility comes from the implementation of novel multi-cavity configurations by inscribing a variety of different fiber Bragg gratings along the different cores of a 7-core fiber. This entails the development of the first fabrication method to inscribe high-quality gratings characterized by arbitrary frequency spectra and located in arbitrary longitudinal positions along the individual cores of a multicore fiber. Our work opens the way towards the development of unique compact fiber-based solutions that enable the implementation of a wide variety of 2D (spatial and wavelength diversity) signal processing functionalities that will be key in future fiber-wireless communications scenarios. We envisage that Microwave Photonics systems and networks will benefit from this technology in terms of compactness, operation versatility and performance stability.

  19. Continuous liquid level sensor based on a reflective long period fiber grating interferometer

    Science.gov (United States)

    Xue, Hao; Xu, Zuowei; Chen, Hao; Yang, Yunyun; You, Jianzhou; Yan, Jiarong; Fu, Hongyan; Zhang, Dan

    2015-03-01

    A continuous liquid level sensor (LLS) based on an in-fiber Michelson interferometer is proposed and experimentally demonstrated. The in-fiber Michelson interferometer is formed by a single long period grating (LPG) together with a reflective mirror at the end of the fiber. The portion between the mirror and LPG is immersed in the liquid to be measured as an LLS sensing probe, and the liquid level can be measured by monitoring the wavelength of interference fringes of the in-fiber Michelson interferometer. The experimental results show that the proposed LLS has a good sensing linearity and sensitivity.

  20. 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.

  1. 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.

  2. Tapered and linearly chirped fiber Bragg gratings with co-directional and counter-directional resultant chirps

    Science.gov (United States)

    Osuch, Tomasz

    2016-05-01

    A method of spectral width tailoring of tapered fiber Bragg gratings is theoretically analyzed and experimentally verified. This concept is based on inscription grating structures in which synthesis of chirps comes from both taper profile and a linearly chirped phase mask used for grating inscription. It is shown that under UV exposure and depending on the orientation of the optical fiber taper relative to the variable-pitch phase mask, tapered and linearly chirped fiber Bragg gratings (TCFBG) with resultant co-directional or counter-directional chirps are achieved. Thus, both effects, those of reduction and enhancement of the grating chirp, as well as their influence on the grating spectral response, are presented. In particular, using the above approach TCFBG with significantly narrowed spectral width are shown. Moreover, fused tapered chirped FBG with relatively large waist diameter are shown having broad spectrum, something that prior to now was not attainable using previously developed techniques.

  3. Precision phase-shifting applied to fiber Bragg gratings

    DEFF Research Database (Denmark)

    Canning, John; Deyerl, Hans-Jürgen; Kristensen, Martin

    2005-01-01

    A simple method of displacing a holographic interferogram within a waveguide based on translation along a slightly tilted fringe pattern of the optical interferogram is presented. By way of example, phase-shifted fibre gratings are produced this way. The spatial resolution in fringe shift is sepa...

  4. Precision phase-shifting applied to fiber Bragg gratings

    DEFF Research Database (Denmark)

    Canning, John; Deyerl, Hans-Jürgen; Kristensen, Martin

    2005-01-01

    A simple method of displacing a holographic interferogram within a waveguide based on translation along a slightly tilted fringe pattern of the optical interferogram is presented. By way of example, phase-shifted fibre gratings are produced this way. The spatial resolution in fringe shift is sepa...

  5. Asymmetric mode coupling in arc-induced long-period fiber gratings

    Science.gov (United States)

    Martinez-Rios, A.; Torres-Gomez, I.; Anzueto-Sanchez, G.; Selvas-Aguilar, R.; Duran-Ramirez, V. M.; Guerrero-Viramontes, J. A.; Toral-Acosta, D.; Salceda Delgado, G.; Castillo-Guzman, A.

    2016-04-01

    An extensive experimental study of the transverse modal field characteristics of mircrobend arc-induced long-period fiber gratings is presented. A wavelength scanning of the near-field intensity pattern inside each loss band in the transmission spectrum, shows a clear asymmetry in the transverse intensity distribution resulting from the fabrication method. This asymmetry reflects as a 10.7 dB difference in the notch depths for two orthogonal polarizations. Though a one year study, it was found that that environmental conditions during fabrication strongly affects the gratings characteristics. The best performance was obtained during the autumn season, where microbend arc-induced long-period fiber gratings produce wavelength filters with short lengths (between 10 and 30 periods for depths in excess of 20 dB) and the insertion loss may be as low as 0.12 dB.

  6. 300 m optic fiber Bragg grating temperature sensing system for seawater measurement

    Energy Technology Data Exchange (ETDEWEB)

    Li Xingrong; Li Yongqian; Wen Zhengyang, E-mail: li_xingrong@yahoo.cn [Department of Electronics and Communication Engineering, North China Electric Power University, Baoding 071003 (China)

    2011-02-01

    Optic fiber grating sensor is a research hotspot.It has been used on many occasions,and how to use it for ocean detection is a new research directions. The paper introduced the calibration work of FBG temperature sensors. It confirmed that from being armored package,the sensors can eliminate the water pressure effect. From the calibration experiment and data processing,60 sensors has little error were screened out for experiment. 300 m long optic fiber Bragg grating sensor array was designed.The marine experiments were achived in South China Sea with 300 meters long Bragg grating array and got the seawater profile temperature. Proposed the curve fitting method to process the data based on Levenberg-Marquardt algorithm. By curve fitting to the data acquired,the precision was better than 0.2 deg. C, which verified the effectiveness of the method.This result has practical value.

  7. Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating.

    Science.gov (United States)

    Pérez-Millán, P; Díez, A; Andrés, M; Zalvidea, D; Duchowicz, R

    2005-06-27

    We report an actively Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating. The laser employs a pair of Bragg gratings as reflective mirrors, one of which is bonded to a magnetostrictive element. Lengthening of the magnetostrictive element when a magnetic field is applied shifts the Bragg wavelength of the grating, allowing control of the Q-factor of the cavity and, thus, performing active Q-switching. The magnetostrictive modulator is small, compact and requires less than 300 mW electrical drive power. Using erbium-doped fiber and a maximum pump power of 120 mW, Q-switch pulses of more than 1 W peak power were obtained, with a pulse repetition rate that can be continuously varied from 1 Hz to 125 kHz.

  8. Fast Inverse Nonlinear Fourier Transforms for Fiber Bragg Grating Design and Related Problems

    CERN Document Server

    Wahls, Sander

    2016-01-01

    The problem of constructing a fiber Bragg grating profile numerically such that the reflection coefficient of the grating matches a given specification is considered. The well-known analytic solution to this problem is given by a suitable inverse nonlinear Fourier transform (also known as inverse scattering transform) of the specificed reflection coefficient. Many different algorithms have been proposed to compute this inverse nonlinear Fourier transform numerically. The most efficient ones require $\\mathcal{O}(D^{2})$ floating point operations (flops) to generate $D$ samples of the grating profile. In this paper, two new fast inverse nonlinear Fourier transform algorithms that require only $\\mathcal{O}(D\\log^{2}D)$ flops are proposed. The merits of our algorithms are demonstrated in numerical examples, in which they are compared to a conventional layer peeling method, the Toeplitz inner bordering method and integral layer peeling. One of our two algorithms also extends to the design problem for fiber-assiste...

  9. Microfluidic refractometer with integrated optical fibers and end-facet transmission gratings.

    Science.gov (United States)

    Lei, Lei; Li, Hao; Shi, Jian; Chen, Yong

    2010-02-01

    We demonstrated a microfluidic refractometer with an integrated high resolution transmission grating. This grating was fabricated by UV nanoimprinting on the end facet of a multimode optical fiber which was then placed in the plan of the microfluidic device and perpendicular to a microchannel. On the opposite side of the channel, three cleaved optical fibers were added for the light collection of the zeroth and the +/- first diffraction orders. A white light source was used for illumination and the diffraction beams were analyzed with a minispectrometer. The transmission grating was merged in the sample solution of the channel, providing a refractive index-dependent diffraction efficiency. As expected, the diffraction efficiency of the zeroth and the +/- first diffraction orders are different, both being reliable for the refractive index monitoring. Such a white source and multibeam diffraction analysis also allows monitoring the sample absorption or fluorescence, thereby providing a more accurate determination of the sample refraction index.

  10. Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating

    Science.gov (United States)

    Pérez-Millán, P.; Díez, A.; Andrés, M. V.; Zalvidea, D.; Duchowicz, R.

    2005-06-01

    We report an actively Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating. The laser employs a pair of Bragg gratings as reflective mirrors, one of which is bonded to a magnetostrictive element. Lengthening of the magnetostrictive element when a magnetic field is applied shifts the Bragg wavelength of the grating, allowing control of the Q-factor of the cavity and, thus, performing active Q-switching. The magnetostrictive modulator is small, compact and requires less than 300 mW electrical drive power. Using erbium-doped fiber and a maximum pump power of 120 mW, Q-switch pulses of more than 1 W peak power were obtained, with a pulse repetition rate that can be continuously varied from 1 Hz to 125 kHz.

  11. Double-clad erbium/ytterbium-doped fiber laser with a fiber Bragg grating

    Science.gov (United States)

    Moghaddam, M. R. A.; Harun, S. W.; Tamjis, M. R.; Ahmad, H.

    2009-08-01

    A double-clad erbium/ytterbium-doped fiber laser (EYDFL) is demonstrated using a fiber Bragg grating (FBG) as wavelength selective filter in a linear cavity resonator. The effect of the FBG's wavelength on the performance of the EYDFL is also investigated. The slope efficiencies of the EYDFL are obtained at 33.7%, 30.9%, and 24.1% for the operating wavelengths of 1553.6, 1557.3, and 1562.8 nm, respectively. The efficiency is higher with a shorter wavelength due to the amplification characteristic of the EYDF which peaks at 1545 nm. At FBG's wavelength of 1553.6 nm, the EYDFL has an output power of 520 mW when pumped at 1700 mW by a 937 nm laser diode. The laser also has a spectral bandwidth of 0.2 nm and signal to noise ratio of more than 25 dB. The threshold power to achieve lasing is measured to be approximately 90 mW for this laser.

  12. A fiber-optic weigh-in-motion sensor using fiber Bragg gratings

    Science.gov (United States)

    Wang, Ke; Wei, Zhanxiong; Chen, Bingquan; Cui, Hong-Liang

    2005-11-01

    In this weigh-in-motion (WIM) research, we introduce a novel design of WIM system based-on fiber Bragg grating (FBG) technologies. The novel design comes from the idea using in-service bridge as the weigh scale. While vehicles traveling over the bridge, the weights can be recorded by the strain gauges installed on the bridge abutments. In this system, the bridge beam is replaced by a piece of steel plate which supports the weight of the traveling vehicle. Four steel tubes are attached firmly at the corners of the plate serving as the bridge abutments. All weights will be finally transferred into the tubes where four FBGs are attached and can record the weight-induced strains by shifting their Bragg wavelengths. Compared with other designs of fiber-optic WIM systems, this design is easy and reliable. Especially it's suitable for heavy vehicles because of its large capacity, such as military vehicles, trucks and trailers. Over 40-ton load has been applied on the system and the experimental results show a good repeatability and linearity under such a large load. The system resolution has been achieved as low as 10 kg.

  13. 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.

  14. Simplified sensor design for temperature-strain discrimination using fiber Bragg gratings embedded in laminated composites

    Science.gov (United States)

    Rodriguez-Cobo, L.; Marques, A. T.; Lopez-Higuera, J. M.; Santos, J. L.; Frazão, O.

    2013-05-01

    Several easy-to-manufacture designs based on a pair of Fiber Bragg Gratings structure embedded in Carbon Fiber Reinforced Plastic (CFRP) have been explored. These smart composites can be used for strain and temperature discrimination. A Finite Elements Analysis and Matlab software were used to study the mechanical responses and its optical behaviors. The results exhibited different sensitivity and using a matrix method it is possible to compensate the thermal drift in a real application keeping a simple manufacture process.

  15. Linear and nonlinear optical properties of carbon nanotube-coated single-mode optical fiber gratings.

    Science.gov (United States)

    Villanueva, Guillermo E; Jakubinek, Michael B; Simard, Benoit; Oton, Claudio J; Matres, Joaquín; Shao, Li-Yang; Pérez-Millán, Pere; Albert, Jacques

    2011-06-01

    Single-wall carbon nanotube deposition on the cladding of optical fibers has been carried out to fabricate an all-fiber nonlinear device. Two different nanotube deposition techniques were studied. The first consisted of repeatedly immersing the optical fiber into a nanotube supension, increasing the thickness of the coating in each step. The second deposition involved wrapping a thin film of nanotubes around the optical fiber. For both cases, interaction of transmitted light through the fiber core with the external coating was assisted by the cladding mode resonances of a tilted fiber Bragg grating. Ultrafast nonlinear effects of the nanotube-coated fiber were measured by means of a pump-probe pulses experiment. © 2011 Optical Society of America

  16. New transfer matrix method for long-period fiber gratings with coupled multiple cladding modes

    Institute of Scientific and Technical Information of China (English)

    Guodong Wang; Yunjian Wang

    2011-01-01

    A new transfer matrix method for long-period fiber gratings with coupled multiple cladding modes is proposed and numerically characterized. The transmission spectra of uniform and non-uniform long-period fiber gratings are numerically characterized. The theoretical results excellently agree with the experimental measurements. Compared with commonly used methods, such as using the fourth-order adaptive step size control of the Runge-Kutta algorithm in solving the coupled mode equation, the new transfer matrix method exhibits a faster calculation speed.%@@ A new transfer matrix method for long-period fiber gratings with coupled multiple cladding modes is proposed and numerically characterized.The transmission spectra of uniform and non-uniform longperiod fiber gratings are numerically characterized.The theoretical results excellently agree with the experimental measurements.Compared with commonly used methods,such as using the fourth-order adaptive step size control of the Runge-Kutta algorithm in solving the coupled mode equation,the new transfer matrix method exhibits a faster calculation speed.

  17. On-chip tunable long-period grating devices based on liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Wei, Lei; Weirich, Johannes; Alkeskjold, Thomas Tanggaard;

    2009-01-01

    We design and fabricate an on-chip tunable long-period grating device by integrating a liquid crystal photonic bandgap fiber on silicon structures. The transmission axis of the device can be electrically rotated in steps of 45° as well as switched on and off with the response time in the millisec...

  18. On-chip tunable long-period gratings in liquid crystal infiltrated photonic crystal fibers

    DEFF Research Database (Denmark)

    Wei, Lei; Weirich, Johannes; Alkeskjold, Thomas Tanggaard;

    2009-01-01

    An on-chip tunable long-period grating device in a liquid crystal infiltrated photonic crystal fiber is experimentally demonstrated. The depth and position of the notch are tuned electrically and thermally. The transmission axis can be electrically controlled as well as switched on and off....

  19. 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...

  20. Usage of fiber Bragg grating sensors in low earth orbit environment

    NARCIS (Netherlands)

    Park, S.-O.; Moon, J.-B.; Lee, Y.-G.; Kim, C.-G.; Bhowmik, S.

    2008-01-01

    It is widely known that materials exposed to the severe low earth orbit (LEO) environment undergo degradations. For the evaluation of fiber Bragg grating (FBG) sensors in the LEO environment, the reflective spectrum change and the Bragg wavelength shift of FBG sensor were measured during aging

  1. Reduction of the Polarization-Dependent Loss of Long-Period Fiber Gratings by Thermal Heating

    Institute of Scientific and Technical Information of China (English)

    S. T. Oh; S. Y. Chang; W. T. Han; U. C. Paek; Y. Chung

    2003-01-01

    The polarization-dependent loss of UV-written long-period fiber gratings was significantly reduced by increasing the pulse repetition rate of the writing UV beam. The effect is closely related with the enhanced photosensitivity induced by thermal heating.

  2. Usage of fiber Bragg grating sensors in low earth orbit environment

    NARCIS (Netherlands)

    Park, S.-O.; Moon, J.-B.; Lee, Y.-G.; Kim, C.-G.; Bhowmik, S.

    2008-01-01

    It is widely known that materials exposed to the severe low earth orbit (LEO) environment undergo degradations. For the evaluation of fiber Bragg grating (FBG) sensors in the LEO environment, the reflective spectrum change and the Bragg wavelength shift of FBG sensor were measured during aging cycle

  3. High-speed structural monitoring using a Fiber Bragg Grating sensor system

    NARCIS (Netherlands)

    Cheng, L.K.; Oostdijck, B.W.

    2002-01-01

    We have developed a new interrogation/demultiplexing system for Fiber Bragg Grating (FBG) sensor array. Our approach combines a high readout frequency for all the FBG sensor channels with absolute measurement. This combination is in particular of interest for the detection of dynamic loading, which

  4. A packaged, low-cost, robust optical fiber strain sensor based on small cladding fiber sandwiched within periodic polymer grating.

    Science.gov (United States)

    Chiang, Chia-Chin; Li, Chein-Hsing

    2014-06-02

    In the present study, a novel packaged long-period fiber grating (PLPFG) strain sensor is first presented. The MEMS process was utilized to fabricate the packaged optical fiber strain sensor. The sensor structure consisted of etched optical fiber sandwiched between two layers of thick photoresist SU-8 3050 and then packaged with poly (dimethylsiloxane) (PDMS) polymer material to construct the PLPFG strain sensor. The PDMS packaging material was used to prevent the glue effect, wherein glue flows into the LPFG structure and reduces coupling strength, in the surface bonding process. Because the fiber grating was packaged with PDMS material, it was effectively protected and made robust. The resonance attenuation dip of PLPFG grows when it is loading. This study explored the size effect of the grating period and fiber diameter of PLPFG via tensile testing. The experimental results found that the best strain sensitivity of the PLPFG strain sensor was -0.0342 dB/με, and that an R2 value of 0.963 was reached.

  5. Q-switching of an all-fiber laser by acousto-optic modulation of a fiber Bragg grating

    Science.gov (United States)

    Delgado-Pinar, M.; Zalvidea, D.; Diez, A.; Perez-Millan, P.; Andres, M.

    2006-02-01

    We report active Q-switching of an all-fiber laser using a Bragg grating based acousto-optic modulator. Q-switching is performed by modulating a fiber Bragg grating with an extensional acoustic wave. The acoustic wave modulates periodically the effective index profile of the FBG and changes its reflection features. This allows controlling the Q-factor of the cavity. Using 1 m of 300 ppm erbium-doped fiber and a maximum pump power of 180 mW, Q-switch pulses of 10 W of peak power and 82 ns wide were generated. The pulse repetition rate of the laser can be continuously varied from few Hz up to 62.5 kHz.

  6. Narrow linewidth Yb-doped double-cladding fiber laser utilizing fiber Bragg gratings inscribed by femtosecond pulses

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhinan; Shi Jiawei; Zhang Jihuang; Wang Haiyan; Li Yuhua; Lu Peixiang, E-mail: oeyhli@gmail.com, E-mail: lupeixiang@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2011-02-01

    A narrow-linewidth high power laser in all fiber format at 1064 nm is demonstrated. The resonant cavity is composed of two distributed Bragg reflector (DBR) fiber gratings, which were inscribed into the core of the double-cladding fiber by use of 800 nm femtosecond laser pulses and a phase mask. The spectrum of the laser exhibited a narrow linewidth of 21 pm at the output power of 0.8 W. The wavelength and power of the laser featured long term stability.

  7. 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...... various methods of insitu monitoring of strains on such CFRP rods when used in different engineering structures....

  8. 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...... 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....

  9. 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.

  10. Optimization of a fiber grating film sensor based on dual peak resonance

    Institute of Scientific and Technical Information of China (English)

    GU Zheng-tian; Xu Yan-ping; DENG Chuan-lu

    2008-01-01

    Based on the dual peak resonance of long-period fider grating(LPFG),a novel film sensor is presented.in which films sensitive to the surrounding gases are coated on the cladding of the fiber grating region,and the intervals of the dual peak resonant wavelengths change with the film refractive index.According to the coupled-mode theory,a triple-clad numerical model is developed to analyze the relation between the sensitivity S and the thin film optical parameters(the film thickness h3 and the refractive index n3and the fiber grating parameters (the grating period A and the coreindex modulation (o)).By using optimization method,the optimal film optical parameters and the grating structure parameters are obtained.Numerical simulation shows that the sensitivity of this scheme to refractive index of the films is predicted to be more than 10-7.The theomtic analysis provides straightforward foundation for the aetual highly sensitive fdm sensors.

  11. Thermal decay analysis of fiber Bragg gratings at different temperature annealing rates using demarcation energy approximation

    Science.gov (United States)

    Gunawardena, Dinusha Serandi; Lai, Man-Hong; Lim, Kok-Sing; Ahmad, Harith

    2017-03-01

    In this study the thermal degradation of gratings inscribed in three types of fiber namely, PS 1250/1500, SM 1500 and zero water peak single mode fiber is demonstrated. A comparative investigation is carried out on the aging characteristics of the gratings at three different temperature ramping rates of 3 °C/min, 6 °C/min and 9 °C/min. During the thermal annealing treatment, a significant enhancement in the grating reflectivity is observed for PS 1250/1500 fiber from ∼1.2 eV until 1.4 eV which indicates a thermal induced reversible effect. Higher temperature ramping rates lead to a higher regeneration temperature. In addition, the investigation also reflects that regardless of the temperature ramping rate the thermal decay behavior of a specific fiber can be successfully characterized when represented in a demarcation energy domain. Moreover, this technique can be accommodated when predicting the thermal decay characteristics of a specific fiber.

  12. Grating-flanked plasmonic coaxial apertures for efficient fiber optical tweezers.

    Science.gov (United States)

    Saleh, Amr A E; Sheikhoelislami, Sassan; Gastelum, Steven; Dionne, Jennifer A

    2016-09-05

    Subwavelength plasmonic apertures have been foundational for direct optical manipulation of nanoscale specimens including sub-100 nm polymeric beads, metallic nanoparticles and proteins. While most plasmonic traps result in two-dimensional localization, three-dimensional manipulation has been demonstrated by integrating a plasmonic aperture on an optical fiber tip. However, such 3D traps are usually inefficient since the optical mode of the fiber and the subwavelength aperture only weakly couple. In this paper we design more efficient optical-fiber-based plasmonic tweezers combining a coaxial plasmonic aperture with a plasmonic grating coupler at the fiber tip facet. Using full-field finite difference time domain analysis, we optimize the grating design for both gold and silver fiber-based coaxial tweezers such that the optical transmission through the apertures is maximized. With the optimized grating, we show that the maximum transmission efficiency increases from 2.5% to 19.6% and from 1.48% to 16.7% for the gold and silver structures respectively. To evaluate their performance as optical tweezers, we calculate the optical forces and the corresponding trapping potential on dielectric particles interacting with the apertures. We demonstrate that the enahncement in the transmission translates into an equivalent increase in the optical forces. Consequently, the optical power required to achieve stable optical trapping is significantly reduced allowing for efficient localization and 3D manipulation of sub-30 nm dielectric particles.

  13. Quasi-distributed acoustic sensing based on identical low-reflective fiber Bragg gratings

    Science.gov (United States)

    Shang, Ying; Yang, Yuan-Hong; Wang, Chen; Liu, Xiao-Hui; Wang, Chang; Peng, Gang-Ding

    2017-01-01

    A quasi-distributed acoustic sensing (QDAS) scheme based on identical low-reflective fiber Bragg grating is proposed and analyzed theoretically and experimentally. We realize the acoustic demodulation of different location and different frequency simultaneously by using imbalanced Michelson interferometer of φ-OTDR and Phase Generated Carrier technology with 600 identical low-reflective fiber Bragg gratings(FBGs) written on-line during drawing of the ordinary signal mode fibers in an equal separation of 2 m. We further obtain the 1.4 dB of frequency response flatness at the range of 200 Hz-1500 Hz and proportional character of demodulated intensity of acoustic sources with different drive voltage of underwater speaker in the experiment.

  14. 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.

  15. Fiber Bragg grating inscription combining DUV sub-picosecond laser pulses and two-beam interferometry.

    Science.gov (United States)

    Becker, Martin; Bergmann, Joachim; Brückner, Sven; Franke, Marco; Lindner, Eric; Rothhardt, Manfred W; Bartelt, Hartmut

    2008-11-10

    The combination of fiber Bragg grating inscription with femtosecond laser sources and the usage of the Talbot interferometer setup not only gives access to the fabrication of Bragg gratings in new types of materials but also allows, at the same time, to keep the high flexibility of an interferometric setup in choosing the Bragg grating wavelength. Since the spatial and temporal coherence properties of the femtosecond laser source differ strongly from those of conventional laser sources, specific limits and tolerances in the interferometric setup have to be considered. Such limits are investigated on the basis of an analytical ray tracing model. The results are applied to tolerance measurements of fiber Bragg grating reflections recorded with a DUV sub-picosecond laser source at 262 nm. Additionally we demonstrate the wavelength versatility of the two-beam interferometer setup for femtosecond inscription over a 40 nm wavelength band. Inscription experiments in Al/Yb doped silica glasses are demonstrated as a prove for the access to non-photosensitive fibers.

  16. Design and Realization of Uniform Fiber Bragg Grating Used in Dense Wavelength Division Multiplexing Systems

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Relation of optical properties in a uniform fiber Bragg grating(FBG) with its grating parameters and the laser beam engraving conditions is analyzed. The principle and method for designing the uniform FBG used in dense wavelength division multiplexing(DWDM) system is given. By adopting the double exposure technique, with a uniform phase mask and Gaussian laser beam, the uniform FBG used in DWDM system is designed and engraved, whose bandwidth of the main reflection band is about 0.4nm and 0.7nm at -5dB and -25dB respectively.

  17. Alternative technique for biodiesel quality control using an optical fiber long-period grating sensor

    Energy Technology Data Exchange (ETDEWEB)

    Falate, Rosane [Universidade Estadual de Ponta Grossa, PR (Brazil). Dept. de Informatica; Nike, Karen; Costa Neto, Pedro Ramos da [Universidade Tecnologica Federal do Parana, Curitiba (Brazil). Dept. de Quimica; Cacao Junior, Eduardo; Muller, Marcia; Kalinowski, Hypolito Jose; Fabris, Jose Luis [Universidade Tecnologica Federal do Parana, Curitiba (Brazil). Dept. de Fisica]. E-mail: fabris@utfpr.edu.br

    2007-07-01

    We report the use of an optical fiber sensor to measure the soybean oil concentration in samples obtained from the mixture of pure biodiesel and commercial soybean oil. The operation of the device is based on the long-period grating sensitivity to the surrounding medium refractive index, which leads to measurable modifications in the grating transmission spectrum. The proposed analysis method results in errors in the oil concentration of 0.4% and 2.6% for pure biodiesel and commercial soybean oil, respectively. Techniques of total glycerol, dynamic viscosity, density, and hydrogen nuclear magnetic resonance spectroscopy were also employed to validate the proposed method. (author)

  18. Bragg grating induced cladding mode coupling due to asymmetrical index modulation in depressed cladding fibers

    DEFF Research Database (Denmark)

    Berendt, Martin Ole; Grüne-Nielsen, Lars; Soccolich, C.F.

    1998-01-01

    to reduce this problem. None of these designs seems to give complete solutions. In particular, the otherwise promising depressed cladding design gives a pronounced coupling to one LP01 mode, this has been referred to as a Ghost grating. To find the modes of the fiber we have established a numerical mode......-solver based on the staircase-approximation method. The Bragg grating causes coupling between the fundamental LP01 mode and higher order LP1p modes that satisfy phase-matching. The coupling strength is determined by the overlap integral of the LP01, the LP1p mode, and the UV-induced index perturbation. For LP0...

  19. Alternative technique for biodiesel quality control using an optical fiber long-period grating sensor

    Directory of Open Access Journals (Sweden)

    Rosane Falate

    2007-01-01

    Full Text Available We report the use of an optical fiber sensor to measure the soybean oil concentration in samples obtained from the mixture of pure biodiesel and commercial soybean oil. The operation of the device is based on the long-period grating sensitivity to the surrounding medium refractive index, which leads to measurable modifications in the grating transmission spectrum. The proposed analysis method results in errors in the oil concentration of 0.4% and 2.6% for pure biodiesel and commercial soybean oil, respectively. Techniques of total glycerol, dynamic viscosity, density, and hydrogen nuclear magnetic resonance spectroscopy were also employed to validate the proposed method.

  20. A Calibration Method Based on Linear InGaAs in Fiber Grating Sensors Interrogation System

    Institute of Scientific and Technical Information of China (English)

    TAO Jun; ZHANG Xia

    2009-01-01

    In accordance with the characteristics of wavelength shift detection in fiber grating sensor interrogation system, the wavelength interrogation system which uses linear InGaAs as the spectrum receiver is proposed. Orientation of optic spectrum line affects the silt of volume phase grating and size of InGaAs photosensitive unit, thus the calibration method is needed. Based on an analysis of InGaAs imaging model, least square curve fitting method is proposed to detect spectrum wavelength and InGaAs photosensitive unit position. The experimental results show that the methods are effective and the demodulation system precision is improved.

  1. An Optical Fiber Viscometer Based on Long-Period Fiber Grating Technology and Capillary Tube Mechanism

    Directory of Open Access Journals (Sweden)

    Jian-Neng Wang

    2010-12-01

    Full Text Available This work addresses the development and assessment of a fiber optical viscometer using a simple and low-cost long-period fiber grating (LPFG level sensor and a capillary tube mechanism. Previous studies of optical viscosity sensors were conducted by using different optical sensing methods. The proposed optical viscometer consists of an LPFG sensor, a temperature-controlled chamber, and a cone-shaped reservoir where gravitational force could cause fluid to flow through the capillary tube. We focused on the use of LPFGs as level sensors and the wavelength shifts were not used to quantify the viscosity values of asphalt binders. When the LPFG sensor was immersed in the constant volume (100 mL AC-20 asphalt binder, a wavelength shift was observed and acquired using LabVIEW software and GPIB controller. The time spent between empty and 100 mL was calculated to determine the discharge time. We simultaneously measured the LPFG-induced discharge time and the transmission spectra both in hot air and AC-20 asphalt binder at five different temperatures, 60, 80, 100, 135, and 170 Celsius. An electromechanical rotational viscometer was also used to measure the viscosities, 0.15–213.80 Pa·s, of the same asphalt binder at the above five temperatures. A non-linear regression analysis was performed to convert LPFG-induced discharge time into viscosities. Comparative analysis shows that the LPFG-induced discharge time agreed well with the viscosities obtained from the rotational viscometer.

  2. Optical resonance analysis of reflected long period fiber gratings with metal film overlay

    Science.gov (United States)

    Zhang, Guiju; Cao, Bing; Wang, Chinua; Zhao, Minfu

    2008-11-01

    We present the experimental results of a novel single-ended reflecting surface plasma resonance (SPR) based long period fiber grating (LPFG) sensor. A long period fiber grating sensing device is properly designed and fabricated with a pulsed CO2 laser writing system. Different nm-thick thin metal films are deposited on the fiber cladding and the fiber end facet for the excitation of surface plasma waves (SPWs) and the reflection of the transmission spectrum of the LPFG with doubled interaction between metal-dielectric interfaces of the fiber to enhance the SPW of the all-fiber SPR-LPFG sensing system. Different thin metal films with different thicknesses are investigated. The effect of the excited SPW transmission along the fiber cladding-metal interface with silver and aluminum films is observed. It is found that different thicknesses of the metal overlay show different resonant behaviors in terms of resonance peak situation, bandwidth and energy loss. Within a certain range, thinner metal film shows narrower bandwidth and deeper peak loss.

  3. Narrow bandwidth passively mode locked picosecond Erbium doped fiber laser using a 45° tilted fiber grating device.

    Science.gov (United States)

    Wang, Tianxing; Yan, Zhijun; Mou, Chengbo; Liu, Zuyao; Liu, Yunqi; Zhou, Kaiming; Zhang, Lin

    2017-07-10

    An all-fiber passively picosecond mode locked Erbium doped laser using a 45° tilted fiber grating (45° TFG) and a fiber Bragg grating (FBG) is reported in this work. Due to the strong polarization dependent loss (PDL) of 45° TFG and narrow 3-dB bandwidth of FBG, the Erbium doped fiber laser (EDFL) can generate picosecond mode locked pulse based on the nonlinear polarization rotation (NPR) effect. The laser features a repetition rate of 9.67 MHz, a pulse duration of 33 ps, a signal-to-noise ratio (SNR) of 70 dB, an average output power of 1.2 mW, and a single pulse energy of 124 pJ under the pump power of 102 mW. Besides, the central wavelength of the laser can be continuously adjusted from 1550.65 nm to 1551.44 nm. The technique of using a 45° TFG to generate picosecond pulses can be readily extended to other wavelength such as mid-infrared (mid-IR) where fiber polarizing components are either expensive or not available. To the best of our knowledge, the spectral width is the narrowest among all-fiber passively mode locked Erbium-doped laser based on NPR.

  4. Superluminal Propagation in Er3+-doped Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    ZHUO Zhong-chang; SU Xue-mei; YU Yong-sen; ZHENG Wei; ZHANG Yu-shu

    2005-01-01

    The method to pump the FBG written into an Er3+-doped optical fiber is proposed to increase the group velocity of a probing pulse based on the facts that pump-induced process changes the refractive index and dispersion associated with the 4I15/2 -4I13/2 transition in Er3+-doped optical fiber. The system equations are derived. The effects of pump power and doping concentration on the group velocity are discussed.

  5. Multipoint refractive index and temperature fiber optic sensor based on cascaded no core fiber-fiber Bragg grating structures

    Science.gov (United States)

    Zhang, Cheng; Xu, Shan; Zhao, Junfa; Li, Hongqiang; Bai, Hua; Miao, Changyun

    2017-02-01

    A multipoint fiber optic sensor based on two cascaded multimode interferometer (MMI) and fiber Bragg grating (FBG) structures is proposed and demonstrated for simultaneous measurement of refractive index (RI) and temperature. The MMI is fabricated by splicing a section of no-core fiber (NCF) with two single-mode fibers. The suitable NCF lengths of 19.1 and 38.8 mm are selected by simulations to achieve wavelength division multiplexing. The two MMIs are sensitive to RI and temperature with the maximal RI sensitivities of 429.42228 and 399.20718 nm/RIU in the range of 1.333 to 1.419 and the temperature sensitivities of 10.05 and 10.22 pm/°C in the range of 26.4°C to 100°C, respectively. However, the FBGs are only sensitive to the latter with the sensitivities of 10.4 and 10.73 pm/°C. Therefore, dual-parameter measurement is obtained and cross-sensitivity issue can be solved. The distance between the two sensing heads is up to 12 km, which demonstrates the feasibility of long-distance measurement. During measurement, there is no mutual interference to each sensing head. The experimental results show that the average errors of RI are 7.61×10-4 RIU and 6.81×10-4 RIU and the average errors of temperature are 0.017°C and 0.012°C, respectively. This sensor exhibits the advantages of high RI sensitivity, dual-parameter and long-distance measurement, low cost, and easy and repeatable fabrication.

  6. 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.

  7. Long-period grating and its cascaded counterpart in photonic crystal fiber for gas phase measurement.

    Science.gov (United States)

    Tian, Fei; Kanka, Jiri; Du, Henry

    2012-09-10

    Regular and cascaded long period gratings (LPG, C-LPG) of periods ranging from 460 to 590 μm were inscribed in an endlessly single mode photonic crystal fiber (PCF) using CO(2) laser for sensing measurements of helium, argon and acetylene. High index sensitivities in excess of 1700 nm/RIU were achieved in both grating schemes with a period of 460 μm. The sharp interference fringes in the transmission spectrum of C-PCF-LPG afforded not only greatly enhanced sensing resolution, but also accuracy when the phase-shift of the fringe pattern is determined through spectral processing. Comparative numerical and experimental studies indicated LP(01) to LP(03) mode coupling as the principal coupling step for both PCF-LPG and C-PCF-LPG with emergence of multi-mode coupling at shorter grating periods or longer resonance wavelengths.

  8. Detection, Evaluation, and Optimization of Optical Signals Generated by Fiber Optic Bragg Gratings Under Dynamic Excitations

    Science.gov (United States)

    Adamovsky, Grigory; Lekki, John; Lock, James A.

    2002-01-01

    The dynamic response of a fiber optic Bragg grating to mechanical vibrations is examined both theoretically and experimentally. The theoretical expressions describing the consequences of changes in the grating's reflection spectrum are derived for partially coherent beams in an interferometer. The analysis is given in terms of the dominant wavelength, optical bandwidth, and optical path difference of the interfering signals. Changes in the reflection spectrum caused by a periodic stretching and compression of the grating were experimentally measured using an unbalanced Michelson interferometer, a Michelson interferometer with a non-zero optical path difference. The interferometer's sensitivity to changes in dominant wavelength of the interfering beams was measured as a function of interferometer unbalance and was compared to theoretical predictions. The theoretical analysis enables the user to determine the optimum performance for an unbalanced interferometer.

  9. Fiber-chip grating coupler based on interleaved trenches with directionality exceeding 95.

    Science.gov (United States)

    Alonso-Ramos, C; Cheben, P; Ortega-Moñux, A; Schmid, J H; Xu, D-X; Molina-Fernández, I

    2014-09-15

    We propose a fiber-chip grating coupler that interleaves the standard full and shallow etch trenches in a 220 nm thick silicon layer to provide a directionality upward exceeding 95%. By adjusting the separation between the two sets of trenches, constructive interference is achieved in the upward direction independent of the bottom oxide thickness and without any bottom reflectors, overlays, or customized etch depths. We implement a transverse subwavelength structure in the first two grating periods to minimize back-reflections. The grating coupler has a calculated coupling efficiency of CE~-1.05 dB with a 1 dB bandwidth of 30 nm and minimum feature size of 100 nm, compatible with deep-UV lithography.

  10. Active Q-switching of a fiber laser using a modulated fiber Fabry-Perot filter and a fiber Bragg grating

    Science.gov (United States)

    Martínez Manuel, Rodolfo; Kaboko, J. J. M.; Shlyagin, M. G.

    2016-02-01

    We propose and demonstrate a simple and robust actively Q-switched erbium-doped fiber ring cavity laser. The Q-switching is based on dynamic spectral overlapping of two filters, namely a fiber Bragg grating-based filter and a fiber Fabry-Perot tunable filter. Using 3.5 m of erbium-doped fiber and a pump power of only 60 mW, Q-switched pulses with a peak power of 9.7 W and a pulse duration of 500 ns were obtained. A pulse repetition rate can be continuously varied from a single shot to a few KHz.

  11. Relative humidity sensor based on surface plasmon resonance of D-shaped fiber with polyvinyl alcohol embedding Au grating

    Science.gov (United States)

    Yan, Haitao; Han, Daofu; Li, Ming; Lin, Bo

    2017-01-01

    This paper presents the design, fabrication, and characterization of a D-shaped fiber coated with polyvinyl alcohol (PVA) embedding an Au grating-based relative humidity (RH) sensor. The Au grating is fabricated on a D-shaped fiber to match the wave-vector and excite the surface plasmon, and the PVA is embedded in the Au grating as a sensitive cladding film. The refractive index of PVA changes with the ambient humidity. Measurements in a controlled environment show that the RH sensor can achieve a sensitivity of 5.4 nm per relative humidity unit in the RH range from 0% to 70% RH. Moreover, the surface plasmon resonance can be realized and used for RH sensing at the C band of optical fiber communication instead of the visible light band due to the metallic grating microstructure on the D-shaped fiber.

  12. Influence of the fiber Bragg gratings with different reflective bandwidths in high power all-fiber laser oscillator

    Science.gov (United States)

    Wang, Jianming; Yan, Dapeng; Xiong, Songsong; Huang, Bao; Li, Cheng

    2017-01-01

    The effects of large-mode-area (LMA) fiber Bragg gratings (FBGs) with different reflective bandwidths on bi-directionally pumped ytterbium-doped single-mode all-fiber laser oscillator have been investigated experimentally. The forward laser output power and the backward signal leakage were measured and analyzed. It was found that the laser output power and efficiency depended on the bandwidth of the high-reflection (HR) FBG used in the laser cavity. The broader bandwidth gives higher laser efficiency, especially at high power level.

  13. Design of Matched Cladding Fiber with UV-sensitive Cladding for Minimization of Claddingmode Losses in Fiber Bragg Gratings

    DEFF Research Database (Denmark)

    Nielsen, Mads Lønstrup; Berendt, Martin Ole; Bjarklev, Anders Overgaard;

    2000-01-01

    The effect on the Bragg-grating-induced cladding-mode coupling of varying the extent of the photosensitive region in a step-index fiber is analyzed. We introduce a figure of merit for the suppression of cladding-mode loss and compare different matched cladding fiber designs. It is found...... to be advantageous to increase the extent of the photosensitive region. However, no significant improvement is obtained by extending the photosensitive region more than approximately 10 mu m into the cladding. This result is not in agreement with a simple analysis that neglects UV absorption, which suggests...

  14. Single- and dual-wavelength switchable erbium-doped fiber ring laser based on intracavity polarization selective tilted fiber gratings.

    Science.gov (United States)

    Mou, Chengbo; Saffari, Pouneh; Fu, Hongyan; Zhou, Kaiming; Zhang, Lin; Bennion, Ian

    2009-06-20

    We propose and demonstrate a single- and dual-wavelength switchable erbium-doped fiber laser (EDFL) by utilizing intracavity polarization selective filters based on tilted fiber gratings (TFGs). In the cavity, one 45 degrees TFG functions as an in-fiber polarizer and the other 77 degrees TFG is used as a fiber polarization dependent loss (PDL) filter. The combined polarization effect from these two TFGs enables the laser to switch between the single- and the dual-wavelength operation with a single-polarization state at room temperature. The laser output at each wavelength shows an optical signal-to-noise ratio (OSNR) of >60 dB, a side mode suppression ratio (SMSR) of >50 dB, and a polarization extinction ratio of approximately 35 dB. The proposed EDFL can give stable output under laboratory conditions.

  15. Analysis of a new structure Q-switched erbium-doped fiber laser based on fiber grating loop mirror

    Science.gov (United States)

    Cai, Haiwen; Xia, Jiangzhen; Chen, Gaoting; Fang, Zujie; Kim, Insoo S.; Kim, Yohee

    2001-10-01

    In this paper a new structure all fiber Q-switched Erbium-doped fiber laser by using all-fiber wavelength selective intensity modulator based on fiber grating loop mirror (FGLM) was reported. This Q-switched scheme not only modulates loss of the cavity but also selects wavelength. Stable optical pulse with 3 dB linewidth of 0.07 nm, pulse width of 1.4 microsecond(s) , average power of 14.2 mW, and peak power of 1.267 W at 80 mW pump power and 8 KHz repetition rates was obtained in experiments. The generation of single laser pulses and its stability were discussed.

  16. 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

    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...

  17. 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.

  18. Interrogation of fiber Bragg-grating resonators by polarization-spectroscopy laser-frequency locking.

    Science.gov (United States)

    Gagliardi, G; De Nicola, S; Ferraro, P; De Natale, P

    2007-04-02

    We report on an optically-based technique that provides an efficient way to track static and dynamic strain by locking the frequency of a diode laser to a fiber Bragg-grating Fabry-Pérot cavity. For this purpose, a suitable optical frequency discriminator is generated exploiting the fiber natural birefringence and that resulting from the gratings inscription process. In our scheme, a polarization analyzer detects dispersive-shaped signals centered on the cavity resonances without need for additional optical elements in the resonator or any laser-modulation technique. This method prevents degradation of the resonator quality and maintains the configuration relatively simple, demonstrating static and dynamic mechanical sensing below the picostrain level.

  19. 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.

  20. Characterization of notched long-period fiber gratings: effects of periods, cladding thicknesses, and etching depths.

    Science.gov (United States)

    Chiang, Chia-Chin; Tseng, Chien-Chia

    2014-07-10

    This study proposes using an inductively coupled plasma etching process to fabricate notched long-period fiber grating (NLPFG) for sensor applications. The effects of the designed parameters (i.e., different fiber cladding thicknesses, grating periods, and etching depths) are studied to explore the characterization of NLPFG. The characterization as indicated by tests of the NLPF showed that the wavelength of NLPFG produced a redshift with decreases in cladding thickness. The drift rate of the wavelength following changes in thickness was -2.801  nm/μm. In addition, a redshift also was exhibited in the increased period, with a wavelength drift rate corresponding to the size of the period of 1.466  nm/μm. Moreover, the results showed that the transmission loss in the spectra increased with etching depth. The variation rate of transmission loss based on etching depth was -0.458  dB/μm.

  1. Proof of Concept of Impact Detection in Composites Using Fiber Bragg Grating Arrays

    Directory of Open Access Journals (Sweden)

    Ander Montero

    2013-09-01

    Full Text Available Impact detection in aeronautical structures allows predicting their future reliability and performance. An impact can produce microscopic fissures that could evolve into fractures or even the total collapse of the structure, so it is important to know the location and severity of each impact. For this purpose, optical fibers with Bragg gratings are used to analyze each impact and the vibrations generated by them. In this paper it is proven that optical fibers with Bragg gratings can be used to detect impacts, and also that a high-frequency interrogator is necessary to collect valuable information about the impacts. The use of two interrogators constitutes the main novelty of this paper.

  2. Design and synthesis of a packaging polymer enhancing the sensitivity of fiber grating pressure sensor

    Institute of Scientific and Technical Information of China (English)

    Qingzhen Wen; Jinhua Zhu; Shenguang Gong; Junbin Huang; Hongcan Gu; Peizhong Zhao

    2008-01-01

    A packaging polymer (PP-1) that can enhance the sensitivity of fiber Bragg grating (FBG) pressure sensor was designed and synthe-sized from hydroxyl terminated polypropylene oxide oligomers, toluene diisocyanate (TDI), 1,4-butandiol as chain extender, catalyzer,foam agent and foam stabilizer. The testing results show that the Young's modulus, Poisson's ratio of the packaging polymer are 9.0×106N m-2 and 0.49, respectively. The static pressure sensitivity of fiber optical Bragg gratings packaged by PP-1 was discussed.The theoretical pressure sensitivity of FBG packaged with the polymer cylinder is -1.73×10-3 Mpa-1, which is 896 times of that of the bare FBG (-1.93×10-6MPa-1). And its measured pressure sensitivity is -1.10×10-3 Mpa-1, which is 558 times of that of the bare FBG.

  3. Sensitivity Enhancement in Low Cutoff Wavelength Long-Period Fiber Gratings by Cladding Diameter Reduction.

    Science.gov (United States)

    Del Villar, Ignacio; Partridge, Matthew; Rodriguez, Wenceslao Eduardo; Fuentes, Omar; Socorro, Abian Bentor; Diaz, Silvia; Corres, Jesus Maria; James, Stephen Wayne; Tatam, Ralph Peter

    2017-09-13

    The diameter of long-period fiber gratings (LPFGs) fabricated in optical fibers with a low cutoff wavelength was be reduced by hydrofluoric acid etching, enhancing the sensitivity to refractive index by more than a factor of 3, to 2611 nm/refractive index unit in the range from 1.333 to 1.4278. The grating period selected for the LPFGs allowed access to the dispersion turning point at wavelengths close to the visible range of the optical spectrum, where optical equipment is less expensive. As an example of an application, a pH sensor based on the deposition of a polymeric coating was analyzed in two situations: with an LPFG without diameter reduction and with an LPFG with diameter reduction. Again, a sensitivity increase of a factor of near 3 was obtained, demonstrating the ability of this method to enhance the sensitivity of thin-film-coated LPFG chemical sensors.

  4. Fiber Bragg grating assisted surface plasmon resonance sensor with graphene oxide sensing layer

    Science.gov (United States)

    Arasu, P. T.; Noor, A. S. M.; Shabaneh, A. A.; Yaacob, M. H.; Lim, H. N.; Mahdi, M. A.

    2016-12-01

    A single mode fiber Bragg grating (FBG) is used to generate Surface Plasmon Resonance (SPR). The uniform gratings of the FBG are used to scatter light from the fiber optic core into the cladding thus enabling the interaction between the light and a thin gold film in order to generate SPR. Applying this technique, the cladding around the FBG is left intact, making this sensor very robust and easy to handle. A thin film of graphene oxide (GO) is deposited over a 45 nm gold film to enhance the sensitivity of the SPR sensor. The gold coated sensor demonstrated high sensitivity of approximately 200 nm/RIU when tested with different concentrations of ethanol in an aqueous medium. A 2.5 times improvement in sensitivity is observed with the GO enhancement compared to the gold coated sensor.

  5. Intensity-modulated relative humidity sensing with polyvinyl alcohol coating and optical fiber gratings.

    Science.gov (United States)

    Yang, Jingyi; Dong, Xinyong; Ni, Kai; Chan, Chi Chu; Shun, Perry Ping

    2015-04-01

    A relative humidity (RH) sensor in reflection mode is proposed and experimentally demonstrated by using a polyvinyl alcohol (PVA)-coated tilted-fiber Bragg grating (TFBG) cascaded by a reflection-band-matched chirped-fiber Bragg grating (CFBG). The sensing principle is based on the RH-dependent refractive index of the PVA coating, which modulates the transmission function of the TFBG. The CFBG is properly designed to reflect a broadband of light spectrally suited at the cladding mode resonance region of the TFBG, thus the reflected optical signal passes through and is modulated by the TFBG again. As a result, RH measurements with enhanced sensitivity of ∼1.80  μW/%RH are realized and demodulated in the range from 20% RH to 85% RH.

  6. 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.

  7. Research on the surface subsidence monitoring technology based on fiber Bragg grating sensing

    Science.gov (United States)

    Wang, Jinyu; Jiang, Long; Sun, Zengrong; Hu, Binxin; Zhang, Faxiang; Song, Guangdong; Liu, Tongyu; Qi, Junfeng; Zhang, Longping

    2017-03-01

    In order to monitor the process of surface subsidence caused by mining in real time, we reported two types of fiber Bragg grating (FBG) based sensors. The principles of the FBG-based displacement sensor and the FBG-based micro-seismic sensor were described. The surface subsidence monitoring system based on the FBG sensing technology was designed. Some factual application of using these FBG-based sensors for subsidence monitoring in iron mines was presented.

  8. Simultaneous Strain and Temperature Measurement with Optical Fiber Gratings: Error Analysis

    Institute of Scientific and Technical Information of China (English)

    JIA Hongzhi; LI Yulin

    2000-01-01

    Many schemes designed to simultaneously measure strain and temperature with optical fiber grating sensors have been reported in recent years. In this paper, the influence of systematic errors associated with the measurement process is analyzed and the error formulas are derived. The results are applied to a range of techniques that are of current interest in the literature. The performance of these schemes is contrasted with respect to the influence of wavelength measurement error and sensitivity matrix error.

  9. Convention of Optical Vortices in Two-Helix Long-Period Fiber Gratings

    Institute of Scientific and Technical Information of China (English)

    Xiao-Qiang Zhang; Rui-Shan Chen; Yong Zhou; Hai Ming; An-Ting Wang

    2016-01-01

    An effective method to fabricate two-helix long-period fiber gratings (TH-LFGs) is presented.Based on the coupling mode theory,the conversion of optical vortices (OVs) in TH-LFGs are analyzed in detail.The conversions of OVs with different topological charges:0 → ±2 and 1 → 3 are simulated as three examples and the conversion efficiency higher than 98% can be realized.

  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 new method for analyzing the characteristics of sampled chirped fiber grating

    Institute of Scientific and Technical Information of China (English)

    孙成城; 李春赟; 于小宇

    2002-01-01

    On the basis of the coherence theory a new method is presented to analyze the sampled chirped fiber gratings (SCFG). With this method, more results on the SCFG are obtained, including not only the characteristics of reflectivity, transmission and time delay, but also the simplified reflectivity formula, the channel's number, wavelength spacing and channel's bandwidth. Therefore, this method is more systematic and perfect than the usual transfer matrix method and can well guide the design of the SCFG.

  12. In-line fiber Bragg grating sensors for steel corrosion detection

    Science.gov (United States)

    Deng, Fodan; Huang, Ying; Azarmi, Fardad

    2016-04-01

    A corrosion monitoring system for steel using Fiber Bragg grating (FBG) sensors is proposed. FBG sensors were protected by hypodermic tubes and a layer of adhesive. The increase in volume caused by the presence of corrosion product introduces strain that can be monitored by FBG sensors. Experimental results showed a positive correlation between the strain and corrosion product, and the change in central wavelength has the potential to serve as an indicator for material weight loss due to corrosion.

  13. 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.

  14. 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.

  15. Experimental Study on Friction in Ferrules during Compression Tuning of Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    Ling Zhao; Jianxin Geng; Lin Li; Zujie Fang

    2003-01-01

    The effect of friction in ferules on compression tuning characteristics of fiber Bragg gratings (FBG) was observed and analyzed in this paper. It was demonstrated that the friction would make a non-uniform strain in the FBG and degradations of its reflection spectrum. To avoid the effect, some measures have been applied. Near 9 nm tuning range can be obtained with good spectral performance.

  16. A novel temperature-insensitive strain sensor based on tapered fiber grating

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel temperature-insensitive strain sensor based on bandwidth demodulation of the reflected light from the tapered fiber grating is presented, which is simple and low-cost and has considerable potential particularly application for strain sensing,and with the development of the interrogation system, it can demodulate both the bandwidth and the center wavelength of the reflected light from TFG to measure strain and temperature simultaneously.

  17. Investigation of fiber Bragg grating as a spectral notch shaper for single-pulse coherent anti-Stokes Raman spectroscopy

    Science.gov (United States)

    Oh, Seung Ryeol; Park, Joo Hyun; Kim, Kyung-Soo; Lee, Eun Seong; Lee, Jae Yong; Kim, Soohyun

    2017-01-01

    We experimentally demonstrate compact and efficient single-pulse coherent anti-Stokes Raman spectroscopy (CARS) via spectral notch shaping implemented with a fiber Bragg grating. We show that a fiber Bragg grating can serve as a narrowband notch filtering component on a 90 nm broadband femtosecond pulsed laser without spectral distortion. Finally, we obtain CARS spectra of various samples in the fingerprint region of molecular vibrations. This scheme has potential for compact implementations of all-fiber single-pulse multiplex CARS due to its compatibility with fiber optics.

  18. Formaldehyde sensing with plasmonic near-infrared optical fiber grating sensors

    Science.gov (United States)

    González-Vila, Á.; Debliquy, M.; Lahem, D.; Mégret, P.; Caucheteur, C.

    2016-04-01

    A tilted fiber Bragg grating is photo-inscribed in the core of a single-mode optical fiber, leading to the coupling of cladding mode resonances all along a wide region of the near-infrared spectrum. The grating is then coated with a thin film of gold in order to create a metal-dielectric interface. This way, light propagating through the cladding of the optical fiber is able to excite a surface plasmon wave on the outer interface. As sensitive element, a molecularly imprinted polymer is deposited by electropolymerization as a thin film around the previous gold coating. The thickness of the polymer is controlled by means of the surface plasmon resonance signature in order to preserve a correct surrounding refractive index sensitivity when used in a gaseous environment. The chosen polymer has an affinity to formaldehyde, which is a volatile organic compound worth to detect, especially because of its toxicity for the human being. We report a global wavelength shift of the grating cladding mode resonances in the presence of formaldehyde in gaseous state. This shift is due to a change in the refractive index of the polymer when it bounds to the target molecules. The sensor exhibits a linear response, together with a low limit of detection.

  19. Error analysis and measurement uncertainty for a fiber grating strain-temperature sensor.

    Science.gov (United States)

    Tang, Jaw-Luen; Wang, Jian-Neng

    2010-01-01

    A fiber grating sensor capable of distinguishing between temperature and strain, using a reference and a dual-wavelength fiber Bragg grating, is presented. Error analysis and measurement uncertainty for this sensor are studied theoretically and experimentally. The measured root mean squared errors for temperature T and strain ε were estimated to be 0.13 °C and 6 με, respectively. The maximum errors for temperature and strain were calculated as 0.00155 T + 2.90 × 10(-6) ε and 3.59 × 10(-5) ε + 0.01887 T, respectively. Using the estimation of expanded uncertainty at 95% confidence level with a coverage factor of k = 2.205, temperature and strain measurement uncertainties were evaluated as 2.60 °C and 32.05 με, respectively. For the first time, to our knowledge, we have demonstrated the feasibility of estimating the measurement uncertainty for simultaneous strain-temperature sensing with such a fiber grating sensor.

  20. A personal review of 25 years of fiber grating sensor development

    Science.gov (United States)

    Udd, Eric

    2013-06-01

    Early efforts developing smart structures started with strain sensors based on interferometeric techniques. It immediately became apparent that structural engineers were used to dealing with conventional electrical strain gages and thermocouples with much shorter gage lengths. The fiber grating offered a competitive solution for the measurement of strain and temperature with the advantages of electrical isolation and improved ruggedness. The principal draw back was cost. So early applications involved high value projects where the unique capabilities of the technology offered superior performance. One area of particular interest involved the usage of fiber gratings to sensor more than one parameter simultaneously. Multi-dimensional strain and the measurement of pressure and temperature were two key examples of multi-parameter sensing. In parallel efforts were conducted to operate at high speed. Early examples in aerospace and civil structures were at speeds in the range of 10 kHz. Ballistic work later dictated increasing speeds to 5 MHz. Much more recent work with burn, deflagration and detonation has involved measurements from more than 100 MHz to multiple GHz. This paper provides a personal history of some of these developments and how fiber grating sensor technology is moving into the future.

  1. Design of a Multicast Optical Packet Switch Based on Fiber Bragg Grating Technology for Future Networks

    Science.gov (United States)

    Cheng, Yuh-Jiuh; Yeh, Tzuoh-Chyau; Cheng, Shyr-Yuan

    2011-09-01

    In this paper, a non-blocking multicast optical packet switch based on fiber Bragg grating technology with optical output buffers is proposed. Only the header of optical packets is converted to electronic signals to control the fiber Bragg grating array of input ports and the packet payloads should be transparently destined to their output ports so that the proposed switch can reduce electronic interfaces as well as the bit rate. The modulation and the format of packet payloads may be non-standard where packet payloads could also include different wavelengths for increasing the volume of traffic. The advantage is obvious: the proposed switch could transport various types of traffic. An easily implemented architecture which can provide multicast services is also presented. An optical output buffer is designed to queue the packets if more than one incoming packet should reach to the same destination output port or including any waiting packets in optical output buffer that will be sent to the output port at a time slot. For preserving service-packet sequencing and fairness of routing sequence, a priority scheme and a round-robin algorithm are adopted at the optical output buffer. The fiber Bragg grating arrays for both input ports and output ports are designed for routing incoming packets using optical code division multiple access technology.

  2. Simultaneous measurement of dynamic strain and temperature distribution using high birefringence PANDA fiber Bragg grating

    Science.gov (United States)

    Zhu, Mengshi; Murayama, Hideaki

    2017-04-01

    New approach in simultaneous measurement of dynamic strain and temperature has been done by using a high birefringence PANDA fiber Bragg grating sensor. By this technique, we have succeeded in discriminating dynamic strain and temperature distribution at the sampling rate of 800 Hz and the spatial resolution of 1 mm. The dynamic distribution of strain and temperature were measured with the deviation of 5mm spatially. In addition, we have designed an experimental setup by which we can apply quantitative dynamic strain and temperature distribution to the fiber under testing without bounding it to a specimen.

  3. High resolution magnetostriction measurements in pulsed magnetic fields using fiber Bragg gratings.

    Science.gov (United States)

    Daou, Ramzy; Weickert, Franziska; Nicklas, Michael; Steglich, Frank; Haase, Ariane; Doerr, Mathias

    2010-03-01

    We report on a new high resolution apparatus for measuring magnetostriction suitable for use at cryogenic temperatures in pulsed high magnetic fields which we have developed at the Hochfeld-Magnetlabor Dresden. Optical fiber strain gauges based on fiber Bragg gratings are used to measure the strain in small (approximately 1 mm) samples. We describe the implementation of a fast measurement system capable of resolving strains in the order of 10(-7) with a full bandwidth of 47 kHz, and demonstrate its use on single crystal samples of GdSb and GdSi.

  4. Bragg grating writing in PMMA microstructured polymer optical fibers in less than 7 minutes

    DEFF Research Database (Denmark)

    Bundalo, Ivan-Lazar; Nielsen, Kristian; Markos, Christos;

    2014-01-01

    We demonstrate fiber Bragg grating (FBG) writing in PMMA microstructured Polymer Optical Fibers (mPOFs) using UV Phase Mask technique with writing times shorter than 10 min. The shortest writing time was 6 minutes and 50 seconds and the longest writing time was 8 min and 50 sec. The FBGs were...... written in a 125 x00B5;m PMMA mPOF having 3-rings of holes, the reflection peaks were centred at 632.6 nm and have a reflectivity as high as 26 dB. We also demonstrate how the writing dynamics depends on the intensity of the writing beam....

  5. Design and optimization of fundamental mode filters based on long-period fiber gratings

    Science.gov (United States)

    Chen, Ming-Yang; Wei, Jin; Sheng, Yong; Ren, Nai-Fei

    2016-07-01

    A segment of long-period fiber grating (LPFG) that can selectively filter the fundamental mode in the few-mode optical fiber is proposed. By applying an appropriate chosen surrounding material and an apodized configuration of LPFG, high fundamental mode loss and low high-order core mode loss can be achieved simultaneously. In addition, we propose a method of cascading LPFGs with different periods to expand the bandwidth of the mode filter. Numerical simulation shows that the operating bandwidth of the cascade structure can be as large as 23 nm even if the refractive index of the surrounding liquid varies with the environment temperature.

  6. Magnetic induction-induced resistive heating of optical fibers and gratings.

    Science.gov (United States)

    Canning, John; Naqshbandi, Masood; Cook, Kevin; Huyang, George

    2013-03-15

    Magnetic induction heating of optical fibers packaged with a steel plate is studied using a fiber Bragg grating. The dependence on the induced wavelength shift with magnetic field is obtained for a commercially available induction heater. More than a 300°C temperature rise is observed within seconds. The potential of magnetic induction as an efficient and rapid means of modulating devices and as a novel approach to potential optical based magnetic field and current sensing is proposed and discussed. The extension of the ideas into micro and nanophotonics is described.

  7. Sensitivity optimization with cladding-etched long period fiber gratings at the dispersion turning point.

    Science.gov (United States)

    Del Villar, Ignacio; Cruz, Jose L; Socorro, Abian B; Corres, Jesus M; Matias, Ignacio R

    2016-08-08

    This work presents a refractive index sensor based on a long period fiber grating (LPFG) made in a reduced cladding fiber whose low order cladding modes have the turning point at large wavelengths. The combination of these parameters results in an improved sensitivity of 8734 nm/refractive index unit (RIU) for the LP0,3 mode in the 1400-1650 wavelength range. This value is similar to that obtained with thin-film coated LPFGs, which permits to avoid the coating deposition step. The numerical simulations are in agreement with the experimental results.

  8. Refractometric sensor based on a phase-shifted long-period fiber grating.

    Science.gov (United States)

    Falate, Rosane; Frazão, Orlando; Rego, Gaspar; Fabris, José Luís; Santos, José Luís

    2006-07-20

    A refractometric sensor based on a phase-shifted long-period fiber grating written by electric-arc discharges is presented. Transmission and reflective configurations for refractive index measurements are studied. It is observed that the reflective topology permits better performance compared with the transmission one, which is the approach normally utilized in the context of long-period fiber sensing. The resolution achieved in the measurement of refractive index enables the application of this sensing head structure in demanding situations, such as the measurement of the level of salinity of water.

  9. Bragg grating-based fiber laser vibration sensing system with novel phase detection

    Science.gov (United States)

    Yang, Xiufeng; Chen, Zhihao; Teo, Ju Teng; Ng, Soon Huat

    2014-01-01

    We characterized the dynamic response of a Bragg grating-based fiber laser sensing system. The sensing system comprises of a narrow line width fiber laser based on π-phase-shifted fiber Bragg grating formed in an active fiber, an unbalanced fiber Michelson interferometer (FMI), which performs wavelength-to-phase mapping, and a phase detection algorithm, which acquires the phase change from the interferometric output signal. The novel phase detection algorithm is developed based on the combination of the two traditional phase generated carrier algorithms: differential-cross-multiplying and arctangent algorithms, and possesses the advantages of the two algorithms. The modulation depth fluctuation of the carrier does not affect the performance of the sensing system. A relatively high side mode suppression ratio of above 50 dB has been achieved within a wide range of carrier amplitude from 1.6 to 5.0 V which correspond to the modulation depth from 1.314 to 4.106 rad. The linearity is 99.082% for the relationship between the power spectral density (dBm/Hz) of the detected signal and the amplitude (mv) of the test signal. The unbalanced FMI is used to eliminate the polarization effect.

  10. High Purcell factor in fiber Bragg gratings utilizing the fundamental slow-light mode.

    Science.gov (United States)

    Skolianos, George; Arora, Arushi; Bernier, Martin; Digonnet, Michel J F

    2015-08-01

    We demonstrate through numerical simulations that the slow-light resonances that exist in strong, apodized fiber Bragg gratings (FBGs) fabricated with femtosecond pulses in deuterium-loaded fibers can exhibit very large intensity enhancements and Purcell factors with the proper optimization of their length. This potential is illustrated with two saturated FBGs that are less than 5 mm long and have been annealed to reduce their internal loss. The first one exhibits the largest measured Purcell factor in an all-fiber device (38.7), and the second one exhibits the largest intensity enhancement (1525). These devices are anticipated to have significant applications in quantum-dot lasers, nonlinear fiber devices, and cavity quantum-electrodynamics experiments.

  11. Femtosecond laser-inscribed fiber Bragg gratings for strain monitoring in power cables of offshore wind turbines.

    Science.gov (United States)

    Burgmeier, Jörg; Schippers, Wolfgang; Emde, Nico; Funken, Peter; Schade, Wolfgang

    2011-05-01

    A fiber Bragg grating sensor system used for monitoring the effects of strain on the power cable of an offshore wind turbine is presented. The Bragg grating structure was inscribed into coated nonphotosensitive standard telecommunication fibers using an IR femtosecond laser and the point-by-point writing technique. Because of the presence of the protective coating of the fiber, the mechanical stability of the resultant sensor device is better than that of a sensor consisting of a bare fiber. A system containing this sensing element was to our knowledge for the first time successfully installed and tested in an offshore wind turbine prototype (REpower 6M, REpower Systems, AG, Germany) in February 2010, near Ellhöft (Germany). The fabrication process of the fiber Bragg gratings, measurement results of the online monitoring, and a comparison between the sensor signal and commonly used sensing techniques are presented.

  12. Technique for writing of fiber Bragg gratings over or near preliminary formed macro-structure defects in silica optical fibers

    Science.gov (United States)

    Evtushenko, Alexander S.; Faskhutdinov, Lenar M.; Kafarova, Anastasia M.; Kazakov, Vadim S.; Kuznetzov, Artem A.; Minaeva, Alina Yu.; Sevruk, Nikita L.; Nureev, Ilnur I.; Vasilets, Alexander A.; Andreev, Vladimir A.; Morozov, Oleg G.; Burdin, Vladimir A.; Bourdine, Anton V.

    2017-04-01

    This work presents method for performing precision macro-structure defects "tapers" and "up-tapers" written in conventional silica telecommunication multimode optical fibers by commercially available field fusion splicer with modified software settings and following writing fiber Bragg gratings over or near them. We developed technique for macrodefect geometry parameters estimation via analysis of photo-image performed after defect writing and displayed on fusion splicer screen. Some research results of defect geometry dependence on fusion current and fusion time values re-set in splicer program are represented that provided ability to choose their "the best" combination. Also experimental statistical researches concerned with "taper" and "up-taper" diameter stability as well as their insertion loss values during their writing under fixed corrected splicer program parameters were performed. We developed technique for FBG writing over or near macro-structure defect. Some results of spectral response measurements produced for short-length samples of multimode optical fiber with fiber Bragg gratings written over and near macro-defects prepared by using proposed technique are presented.

  13. 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.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    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...

  15. Comparative assessment of erbium fiber ring lasers and reflective SOA linear lasers for fiber Bragg grating dynamic strain sensing.

    Science.gov (United States)

    Wei, Heming; Krishnaswamy, Sridhar

    2017-05-01

    Fiber Bragg grating (FBG) dynamic strain sensors using both an erbium-based fiber ring laser configuration and a reflective semiconductor optical amplifier (RSOA)-based linear laser configuration are investigated theoretically and experimentally. Fiber laser models are first presented to analyze the output characteristics of both fiber laser configurations when the FBG sensor is subjected to dynamic strains at high frequencies. Due to differences in the transition times of erbium and the semiconductor (InP/InGaAsP), erbium-doped fiber amplifier (EDFA)- and RSOA-based fiber lasers exhibit different responses and regimes of stability when the FBG is subjected to dynamic strains. The responses of both systems are experimentally verified using an adaptive photorefractive two-wave mixing (TWM) spectral demodulation technique. The experimental results show that the RSOA-FBG fiber linear cavity laser is stable and can stably respond to dynamic strains at high frequencies. An example application using a multiplexed TWM interferometer to demodulate multiple FBG sensors is also discussed.

  16. 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...

  17. 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

    to interrogate liquid level by measuring the strain induced in each mPOFBG embedded in a silicone rubber (SR) diaphragm, which deforms due to hydrostatic pressure variations. The sensor exhibits a highly linear response over the sensing range, a good repeatability, and a high resolution. The sensitivity......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...

  18. Research on a new fiber-optic axial pressure sensor of transformer winding based on fiber Bragg grating

    Science.gov (United States)

    Liu, Yuan; Li, Lianqing; Zhao, Lin; Wang, Jiqiang; Liu, Tongyu

    2017-07-01

    Based on the principle of the fiber Bragg grating, a new type of fiber-optic pressure sensor for axial force measurement of transformer winding is designed, which is designed with the structure of bending plate beam, the optimization of the packaging process, and material of the sensor. Through the calibration experiment to calibrate the sensor, the field test results of the Taikai transformer factory show that the sensitivity of the sensor is 0.133 pm/kPa and the repeatability error is 2.7% FS. The data of the fiber-optic pressure sensor in different positions maintain consistent and repeatable, which can meet the requirement of the real-time monitoring of the axial force of transformer winding.

  19. High-Tg TOPAS microstructured polymer optical fiber for fiber Bragg grating strain sensing at 110 degrees

    DEFF Research Database (Denmark)

    Markos, Christos; Stefani, Alessio; Nielsen, Kristian;

    2013-01-01

    We present the fabrication and characterization of fiber Bragg gratings (FBGs) in an endlessly single-mode microstructured polymer optical fiber (mPOF) made of humidity-insensitive high-Tg TOPAS cyclic olefin copolymer. The mPOF is the first made from grade 5013 TOPAS with a glass transition...... temperature of Tg = 135°C and we experimentally demonstrate high strain operation (2.5%) of the FBG at 98°C and stable operation up to a record high temperature of 110°C. The Bragg wavelengths of the FBGs are around 860 nm, where the propagation loss is 5.1dB/m, close to the fiber loss minimum of 3.67d...

  20. Wideband-adjustable reflection-suppressed rejection filters using chirped and tilted fiber gratings.

    Science.gov (United States)

    Liu, Fu; Guo, Tuan; Wu, Chuang; Guan, Bai-Ou; Lu, Chao; Tam, Hwa-Yaw; Albert, Jacques

    2014-10-06

    Wideband-adjustable band-rejection filters based on chirped and tilted fiber Bragg gratings (CTFBG) are proposed and experimentally demonstrated. The flexible chirp-rate and wide tilt-angle provide the gratings with broadband filtering functions over a large range of bandwidths (from 10 nm to 150 nm), together with a low insertion loss (less than 1 dB) and a negligible back-reflection (lower than -20 dB). The slope profile of CTFBG in transmission can be easily tailored by adjusting the tilt angle, grating irradiation time and chirp rate-grating factor, and it is insensitive to the polarization state of the input light, as well as to temperature, axial strain and surrounding refractive index. Furthermore, by coating the CTFBG with a suitable polymer (whose refractive index is close to that of the cladding glass), the cladding modes no longer form weakly discrete resonances and leave a smoothly varying attenuation spectrum for high-quality band-rejection filters, edge filters and gain equalizers.

  1. A comprehensive study on gain stabilization of Er-doped fiber amplifier in C-band with uniform fiber Bragg grating-pair

    Science.gov (United States)

    Yang, Jiuru; Ma, Yu; OuYang, Yunlun; Liu, Chunyu; Zhang, Jiaxiao

    2014-07-01

    Fiber grating-pair is one of the efficient methods for gain stabilization of erbium doped fiber amplifier (EDFA) but with a gain-reduction of signals, especially in C-band. In order to overcome it, in this article, we establish a configuration of EDFA based uniform fiber grating-pair and conduct a comprehensive study on gain stabilization by varying the reflectivity, center wavelength and 3dB bandwidth of grating, and by varying the channel number and pump power. The numerical results show that under the optimal parameters of grating the gain stabilization at 1550nm is +/-0.044dB with high gain and large dynamic range.

  2. 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.

  3. Structural Health Monitoring with Fiber Bragg Grating and Piezo Arrays

    Science.gov (United States)

    Black, Richard J.; Faridian, Ferey; Moslehi, Behzad; Sotoudeh, Vahid

    2012-01-01

    Structural health monitoring (SHM) is one of the most important tools available for the maintenance, safety, and integrity of aerospace structural systems. Lightweight, electromagnetic-interference- immune, fiber-optic sensor-based SHM will play an increasing role in more secure air transportation systems. Manufacturers and maintenance personnel have pressing needs for significantly improving safety and reliability while providing for lower inspection and maintenance costs. Undetected or untreated damage may grow and lead to catastrophic structural failure. Damage can originate from the strain/stress history of the material, imperfections of domain boundaries in metals, delamination in multi-layer materials, or the impact of machine tools in the manufacturing process. Damage can likewise develop during service life from wear and tear, or under extraordinary circumstances such as with unusual forces, temperature cycling, or impact of flying objects. Monitoring and early detection are key to preventing a catastrophic failure of structures, especially when these are expected to perform near their limit conditions.

  4. Negative axial strain sensitivity in gold-coated eccentric fiber Bragg gratings

    Science.gov (United States)

    Chah, Karima; Kinet, Damien; Caucheteur, Christophe

    2016-11-01

    New dual temperature and strain sensor has been designed using eccentric second-order fiber Bragg gratings produced in standard single-mode optical fiber by point-by-point direct writing technique with tight focusing of 800 nm femtosecond laser pulses. With thin gold coating at the grating location, we experimentally show that such gratings exhibit a transmitted amplitude spectrum composed by the Bragg and cladding modes resonances that extend in a wide spectral range exceeding one octave. An overlapping of the first order and second order spectrum is then observed. High-order cladding modes belonging to the first order Bragg resonance coupling are close to the second order Bragg resonance, they show a negative axial strain sensitivity (-0.55 pm/μɛ) compared to the Bragg resonance (1.20 pm/μɛ) and the same temperature sensitivity (10.6 pm/°C). With this well conditioned system, temperature and strain can be determined independently with high sensitivity, in a wavelength range limited to a few nanometers.

  5. Bragg grating photo-inscription in doped microstructured polymer optical fiber by 400 nm femtosecond laser pulses

    DEFF Research Database (Denmark)

    Hu, X.; Woyessa, Getinet; Kinet, D.;

    2016-01-01

    In this paper, we report the manufacturing of high-quality endlessly single-mode doped microstructured poly(methyl methacrylate) (PMMA) optical fibers. Bragg gratings are photo-inscribed in such fibers by means of 400 nm femtosecond laser pulses through a 1060-nm-period uniform phase mask...

  6. 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.

    Science.gov (United States)

    Maccioni, E; Morganti, M; Brandi, F

    2015-02-01

    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.

  7. Development and Testing of a Plastic Optical Fiber Grating Biosensor for Detection of Glucose in the Blood

    Science.gov (United States)

    Yunianto, M.; Eka, D.; Permata, A. N.; Ariningrum, D.; Wahyuningsih, S.; Marzuki, A.

    2017-02-01

    The objective of this study is to detect glucose content in human blood serum using optical fiber grating with LED wavelength corresponding to the absorption of glucose content in blood serum. The testing used a UV-Vis spectrometer and Rays spectrometers, in which in the ray spectrometer it was used optical fiber biosensor using optical fiber grating. The result obtained is the typical peak of glucose absorption in UV-Vis at 581 nm wavelength and rays spectrometer on green LED at 514.2 nm wavelength with linear regression result by 0.97 and 0.94, respectively.

  8. Tunable wavelength erbium doped fiber linear cavity laser based on mechanically induced long-period fiber gratings

    Science.gov (United States)

    Pérez Maciel, M.; Montenegro Orenday, J. A.; Estudillo Ayala, J. M.; Jáuregui-Vázquez, D.; Sierra-Hernandez, J. M.; Hernandez-Garcia, J. C.; Rojas-Laguna, R.

    2016-09-01

    Tunable wavelength erbium doped fiber linear cavity laser, based on mechanically induced long-period fiber gratings (MLPFG) is presented. The laser was tuned applying pressure over the MLPFG, in order to monitor this, pressure is applied over a plate with periodic grooves that has a short length, this pressure is controlled by a digital torque tester as a result tunable effect is observed. The grooves have a period of 620µm and the maximal pressure without breakpoint fiber is around 0.80lb-in2. Furthermore, the MLPFG used can be erased, reconfigured and exhibit a transmission spectra with termal stability, similar to high cost photoinduced long period gratings. In this work, by pressure increment distributed over the MLPFG from 0.40 lb-in2 to 0. 70 lb-in 2, tuned operation range of 14nm was observed and single line emission was tuned in the C telecommunication band. According to the stability analysis the signal to noise ratio was 29 dB and minimal wavelength oscillations of 0.29nm.

  9. Experimental demonstration of an apodized-imaging chip-fiber grating coupler for Si3N4 waveguides.

    Science.gov (United States)

    Chen, Yang; Domínguez Bucio, Thalia; Khokhar, Ali Z; Banakar, Mehdi; Grabska, Katarzyna; Gardes, Frederic Y; Halir, Robert; Molina-Fernández, Íñigo; Cheben, Pavel; He, Jian-Jun

    2017-09-15

    A silicon nitride waveguide is a promising platform for integrated photonics, particularly due to its low propagation loss compared to other complementary metal-oxide-semiconductor compatible waveguides, including silicon-on-insulator. Input/output coupling in such thin optical waveguides is a key issue for practical implementations. Fiber-to-chip grating couplers in silicon nitride usually exhibit low coupling efficiency because the moderate index contrast leads to weak radiation strengths and poor directionality. Here, we present the first, to the best of our knowledge, experimental demonstration of a recently proposed apodized-imaging fiber-to-chip grating coupler in silicon nitride that images an in-plane waveguide mode to an optical fiber placed at a specific distance above the chip. By employing amplitude and phase apodization, the diffracted optical field of the grating is matched to the fiber mode. High grating directionality is achieved by using staircase grating teeth, which produce a blazing effect. Experimental results demonstrate an apodized-imaging grating coupler with a record coupling efficiency of -1.5  dB and a 3 dB bandwidth of 60 nm in the C-band.

  10. 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.

  11. 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.

  12. Absolute near-infrared refractometry with a calibrated tilted fiber Bragg grating.

    Science.gov (United States)

    Zhou, Wenjun; Mandia, David J; Barry, Seán T; Albert, Jacques

    2015-04-15

    The absolute refractive indices (RIs) of water and other liquids are determined with an uncertainty of ±0.001 at near-infrared wavelengths by using the tilted fiber Bragg grating (TFBG) cladding mode resonances of a standard single-mode fiber to measure the critical angle for total internal reflection at the interface between the fiber and its surroundings. The necessary condition to obtain absolute RIs (instead of measuring RI changes) is a thorough characterization of the dispersion of the core mode effective index of the TFBG across the full range of its cladding mode resonance spectrum. This technique is shown to be competitive with the best available measurements of the RIs of water and NaCl solutions at wavelengths in the vicinity of 1550 nm.

  13. 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.

  14. Sensitivity distribution properties of a phase-shifted fiber bragg grating sensor to ultrasonic waves.

    Science.gov (United States)

    Wu, Qi; Okabe, Yoji; Saito, Kazuya; Yu, Fengming

    2014-01-09

    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.

  15. 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.

  16. Distributed fiber optic interferometric geophone system based on draw tower gratings

    Science.gov (United States)

    Xu, Ruquan; Guo, Huiyong; Liang, Lei

    2017-09-01

    A distributed fiber optic interferometric geophone array based on draw tower grating (DTG) array is proposed. The DTG geophone array is made by the DTG array fabricated based on a near-contact exposure through a phase mask during the fiber drawing process. A distributed sensing system with 96 identical DTGs in an equal separation of 20 m and an unbalanced Michelson interferometer for vibration measurement has been experimentally validated compared with a moving-coil geophone. The experimental results indicate that the sensing system can linearly demodulate the phase shift. Compared with the moving coil geophone, the fiber optic sensing system based on DTG has higher signal-to-noise ratio at low frequency.

  17. 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.

  18. 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.

  19. High resolution grating-assisted surface plasmon resonance fiber optic aptasensor.

    Science.gov (United States)

    Albert, Jacques; Lepinay, Sandrine; Caucheteur, Christophe; Derosa, Maria C

    2013-10-01

    A surface plasmon resonance biochemical sensor based on a tilted fiber Bragg grating imprinted in a single mode fiber core is demonstrated. A 30-50 nm thick gold coating on the cladding of the fiber provides the support for surface plasmon waves whose interaction with attached biomolecules is monitored at near infrared wavelengths near 1,550 nm. The transmission spectrum of the sensor provides a fine comb of narrowband resonances that overlap with the broader absorption of the surface plasmon and thus provide a unique tool to measure small shifts of the plasmon with high accuracy. The attachment on the gold surfaces of aptamers with specific affinities for proteins provides the required target-analyte system and is shown to be functional in the framework of our sensing device. The implementation of the sensor either as a stand-alone device or as part of a multi-sensor platform is also described. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Photonic band-gap engineering in UV fiber gratings by the arc discharge technique.

    Science.gov (United States)

    Cusano, Andrea; Iadicicco, Agostino; Paladino, Domenico; Campopiano, Stefania; Cutolo, Antonello

    2008-09-29

    Localized heat treatments combined with local non-adiabatic tapering is proposed as suitable tool for the engineering of photonic band-gaps in UV-written fiber Bragg gratings (FBGs). In particular, here, we propose the use of the electric arc discharge to achieve localized defects along the FBG structure, however differently from previously reported works, we demonstrate how this post processing tool properly modified can be exploited to achieve the full control of the spectral characteristics of the final device. Also, we show how the suitable choice of the grating features and the correct selection of the defect geometry can be efficiently used to achieve interesting features for both communication and sensing applications.

  1. Novel simulation method for fiber Bragg grating under inhomogeneous strain fields

    Institute of Scientific and Technical Information of China (English)

    YUN Bin-feng; LU Chang-gui; WANG Zhu-yuan; WANG Yi-ping; CUI Yi-ping

    2005-01-01

    The spectra of fiber Bragg grating (FBG) in inhomogeneous strain fields are distorted due to its inhomogeneity of both the periods and the effective refractive index. The couple mode theory and the Runge-Kutta method can be employed for exact simulation of the spectrum of Bragg grating in such field, but the convergence speed is slow. On the other hand, although the transfer matrix method could be used with higher convergence speed, the precision is poor because of the neglect of the grads of strain change. By improving the FBG equivalent period, a novel simulation method based on a modified transfer matrix method is proposed, which has the advantage of quick-convergence as well as good accuracy.

  2. Detection of adulteration in virgin olive oil using a fiber optic long period grating based sensor

    Science.gov (United States)

    Libish, T. M.; Bobby, M. C.; Linesh, J.; Mathew, S.; Pradeep, C.; Nampoori, V. P. N.; Biswas, P.; Bandyopadhyay, S.; Dasgupta, K.; Radhakrishnan, P.

    2013-04-01

    A fiber optic sensing system for the detection of adulteration of virgin olive oil by less expensive sunflower oil is presented. The fundamental principle of detection is the sensitive dependence of the resonance peaks of a long period grating (LPG) on the changes in the refractive index of the environmental medium surrounding the cladding surface of the grating. The performance of the sensor has been tested by monitoring the amplitude changes of the attenuation bands of the LPG in response to variation of adulteration level. With good repeatability, the detection limit of adulteration is 4% and the sensor sensitivity is around 0.07 dB vol%-1 of adulterant in the measurement range. The developed sensor is user-friendly, reusable and allows instantaneous measurement of the amount of adulteration without involving any reagents.

  3. 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.

  4. Improvement on peak-to-trough ratio of sampled fiber Bragg gratings with multiple phase shifts

    Institute of Scientific and Technical Information of China (English)

    Bin Xie; Wei Pan; Bin Luo; Xihua Zou

    2008-01-01

    Via a cascaded structure, the peak-to-trough ratio is considerably improved for sampled fiber Bragg gratings (SFBGs) based on multiple-phase-shift (MPS) technique. This cascaded filter is composed of two identical SFBGs which are inserted with the increasing or decreasing arrangement of phase shifts.With this inverse arrangement of MPS in grating design, the phase fluctuation of individual SFBG can be compensated, and as a result an excellent phase matching condition is realized. In this way, the peak-to-trough ratio in reflection spectra is improved from 6 to 12 dB when multiplication factor m = 4, and from 5 dB to 10 dB when m=8.

  5. 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...

  6. Multiplexed Bragg grating optical fiber sensors for damage evaluation in highway bridges

    Science.gov (United States)

    Idriss, R. L.; Kodindouma, M. B.; Kersey, A. D.; Davis, M. A.

    1998-04-01

    A multiplexed Bragg grating optical fiber monitoring system is designed and integrated at the construction stage in an experimental full scale laboratory bridge. The test bridge is a 40 ft span non-composite steel girder concrete deck bridge. The network of sensors is used to measure the strain throughout the bridge, with sensors bonded to the tension steel in the slab and attached to the bottom flange of the girders. Resistive strain gages and Bragg grating sensors are placed side by side to compare results. The strain data are obtained for the pristine structure, then damage is introduced at midspan for an exterior girder. Several levels of damage in the form of cuts in one of the girders are imposed with the final cut resulting in a half depth fracture of the girder. The load path in the structure is obtained using the built in sensor system.

  7. VCSEL-powered and polarization-maintaining fiber-optic grating vector rotation sensor.

    Science.gov (United States)

    Guo, Tuan; Liu, Fu; Du, Fa; Zhang, Zhaochuan; Li, Chunjie; Guan, Bai-Ou; Albert, Jacques

    2013-08-12

    A compact fiber-optic vector rotation sensor in which a short section of polarization-maintaining (PM) fiber stub containing a straight fiber Bragg grating (FBG) is spliced to another single mode fiber without any lateral offset is proposed and experimentally demonstrated. Due to the intrinsic birefringence of the PM fiber, two well-defined resonances (i.e. orthogonally polarized FBG core modes) with wavelength separation of 0.5 nm have been achieved in reflection, and they exhibit a high sensitivity to fiber rotation. Both the orientation and the angle of rotation can be determined unambiguously via simple power detection of the relative amplitudes of the orthogonal core reflections. Meanwhile, instead of using a broadband source (BBS), the sensor is powered by a commercial vertical cavity surface emitting laser (VCSEL) with the laser wavelength matched to the PM-FBG core modes, which enables the sensor to work at much higher power levels (~15 dB better than BBS). This improves the signal-to-noise ratio considerably (~50 dB), and makes a demodulation filter unnecessary. Vector rotation measurement with a sensitivity of 0.09 dB/deg has been achieved via cost-effective single detector real time power measurement, and the unwanted power fluctuations and temperature perturbations can be effectively referenced out.

  8. Phase-shifted fiber Bragg grating inscription by fusion splicing technique and femtosecond laser

    Science.gov (United States)

    Jiang, Yajun; Yuan, Yuan; Xu, Jian; Yang, Dexing; Li, Dong; Wang, Meirong; Zhao, Jianlin

    2016-11-01

    A new method for phase-shifted fiber Bragg grating (PS-FBG) inscription in single mode fiber by fusion splicing technique and femtosecond laser is presented. The PS-FBG is produced by exposing the fusion spliced fiber with femtosecond laser through a uniform phase mask. The transmission spectrum of the PS-FBG shows a nonlinear red shift during the inscription process, and two or three main dips can be observed due to the formation of one or two FBG-based Fabry-Pérot structures by controlling the exposure intensity and time of the laser. For a peak power density of 4.8×1013 W/cm2, the induced refractive index modulation can reach to 6.3×10-4 in the fiber without sensitization. The PS-FBG's temperature, strain and pressure characteristics are also experimentally studied. These PS-FBGs can be potentially used for multiple wavelength fiber lasers, filters and optical fiber sensors.

  9. Highly sensitive detection of molecular interactions with plasmonic optical fiber grating sensors.

    Science.gov (United States)

    Voisin, Valérie; Pilate, Julie; Damman, Pascal; Mégret, Patrice; Caucheteur, Christophe

    2014-01-15

    Surface Plasmon resonance (SPR) optical fiber biosensors constitute a miniaturized counterpart to the bulky prism configuration and offer remote operation in very small volumes of analyte. They are a cost-effective and relatively straightforward technique to yield in situ (or even possibly in vivo) molecular detection. The biosensor configuration reported in this work uses nanometric-scale gold-coated tilted fiber Bragg gratings (TFBGs) interrogated by light polarized radially to the optical fiber outer surface, so as to maximize the optical coupling with the SPR. These gratings were recently associated to aptamers to assess their label-free biorecognition capability in buffer and serum solutions. In this work, using the well-acknowledged biotin-streptavidin pair as a benchmark, we go forward in the demonstration of their unique sensitivity. In addition to the monitoring of the self-assembled monolayer (SAM) in real time, we report an unprecedented limit of detection (LOD) as low as 2 pM. Finally, an immunosensing experiment is realized with human transferrin (dissociation constant Kd~10(-8) M(-1)). It allows to assess both the reversibility and the robustness of the SPR-TFBG biosensors and to confirm their high sensitivity.

  10. Bragg gratings inscription in step-index PMMA optical fiber by femtosecond laser pulses at 400 nm

    Science.gov (United States)

    Hu, X.; Kinet, D.; Chah, K.; Mégret, P.; Caucheteur, C.

    2016-05-01

    In this paper, we report photo-inscription of uniform Bragg gratings in trans-4-stilbenemethanol-doped photosensitive step-index polymer optical fiber. Gratings were produced at ~1575 nm by the phase mask technique with a femtosecond laser emitting at 400 nm with different average optical powers (8 mW, 13 mW and 20 mW). The grating growth dynamics in transmission were monitored during the manufacturing process, showing that the grating grows faster with higher power. Using 20 mW laser beam power, the reflectivity reaches 94 % (8 dB transmission loss) in 70 seconds. Finally, the gratings were characterized in temperature in the range 20 - 45 °C. The thermal sensitivity has been computed equal to - 86.6 pm/°C.

  11. 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.

  12. Highly efficient vertical fiber interfacing grating coupler with bilayer anti-reflection cladding and backside metal mirror

    Science.gov (United States)

    Zhang, Zanyun; Huang, Beiju; Zhang, Zan; Cheng, Chuantong; Liu, Hongwei; Li, Hongqiang; Chen, Hongda

    2017-05-01

    A highly efficient bidirectional grating coupler for perfectly vertical coupling is designed. With a Si3N4/SiO2 bilayer structure and a backside metal mirror acting as anti-reflection cladding (ARC) and substrate reflector respectively, the coupling efficiency can be greatly enhanced for a cost-effective uniform grating coupler. To maximize the grating coupling, all the grating parameters including the bilayer thicknesses are fully optimized using numerical simulation method. As a design trade-off between coupling efficiency (CE) and optical bandwidth (OB), CE of 88.3% (-0.54 dB) and 1-dB bandwidth of 61 nm can be obtained. In addition, this grating coupler shows strong fiber misalignment tolerance. With a 2 μm fiber misalignment, the coupling loss increases by less than 0.5 dB and the up-reflection loss increases by less than 2 dB. Also it is found that the splitting behavior of the grating is quite stable near the grating resonant wavelength. Such characteristics make this device very attractive for low-cost photonic packaging and Mach-Zehnder type device applications. In addition, two optimal designs are presented based on the Particle Swarm Optimization (PSO) method and genetic algorithm (GA). Numerical calculated results show that the coupling efficiency at center wavelength can be further improved compared to that of the balanced design. However, the optical bandwidth suffer at a expense. At last, Fourier analysis of the grating is carried out to analyze the optical field profile and frequency spectrum of the grating region. It is believed such a grating structure can provide flexible designs for different coupler requirements and applications.

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

    Science.gov (United States)

    Marques, C. A. F.; Pospori, A.; Sáez-Rodríguez, D.; Nielsen, K.; Bang, O.; Webb, D. J.

    2016-04-01

    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 on capacitive, ultrasonic and electric techniques, however they suffer from intrinsic safety concerns in explosive environments combined with issues relating to reliability and maintainability. In the last few years, optical fiber liquid level sensors (OFLLSs) have been reported to be safe and reliable 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 commercialized because they exhibit some drawbacks: low sensitivity, limited range, long-term instability, or limited resolution. In addition, any sensors that involve direct interaction of the optical field with the fuel (either by launching light into the fuel tank or via the evanescent field of a fiber-guided mode) must be able to cope with the potential build up of contamination - often bacterial - on the optical surface. In this paper, a fuel level sensor based on microstructured polymer optical fiber Bragg gratings (mPOFBGs), including poly (methyl methacrylate) (PMMA) and TOPAS fibers, embedded in diaphragms is investigated in detail. The mPOFBGs are embedded in two different types of diaphragms and their performance is investigated with aviation fuel for the first time, in contrast to our previous works, where water was used. Our new system exhibits a high performance when compared with other previously published in the literature, making it a potentially useful tool for aircraft fuel monitoring.

  14. High-birefringence photonic crystal fiber Michelson interferometer with cascaded fiber Bragg grating for pressure and temperature discrimination

    Science.gov (United States)

    Tan, Xiaoling; Geng, Youfu; Li, Xuejin

    2016-09-01

    A simple and compact interferometer for temperature and pressure discrimination is proposed and demonstrated experimentally. It consists of a short section of high-birefringence photonic crystal fiber (Hi-Bi PCF) and a cascaded fiber Bragg grating (FBG). In the Hi-Bi PCF, two orthogonal polarized modes are employed as optical arms to construct, such as a Michelson interferometer. Combined with a cascaded FBG, pressure and temperature measurements are discriminated by a matrix method, and the pressure sensitivity of Hi-Bi PCF is determined to be around 3.65 nm/MPa. The proposed Michelson interferometer is easy-to-fabricate, flexible, and low-cost, which shows great potential in future applications of remote sensing.

  15. Multi-wavelength fiber ring laser based on a chirped moiré fiber grating and a semiconductor optical amplifier

    Institute of Scientific and Technical Information of China (English)

    Shaohua Lu; Ou Xu; Suchun Feng; Shuisheng Jian

    2009-01-01

    A simple and cost-effective multi-wavelength fiber ring laser based on a chirped Moire fiber grating (CMFG)arid a semiconductor optical amplifier (SOA) is proposed.Stable triple-wavelength lasing oscillations at room temperature are experimentally demonstrated.The measured optical signal-to-noise ratio (SNR) reaches the highest value of 50 dB and the power fluctuation of each wavelength is less than 0.2 dB within a 1-h period.To serve as a wavelength selective element,the CMFG possesses excellent comb-like filtering chaxacteristics including stable wavelength interval arid ultra-narrow passband,and its fabrication method is easy and flexible.The lasing oscillation shows a narrower bandwidth than SOA-based multi-wavelength fibcr lasers utilizing some other kinds of wavelength selective components.Methods to optimize the laser performance are also discussed.

  16. A Novel Temperature-Compensated, Intensity-Modulated Fiber Bragg Grating Sensor System

    Institute of Scientific and Technical Information of China (English)

    Xin-Yong Dong; Hwa-Yaw Tam

    2008-01-01

    An intensity-modulated, fiber Bragg grating (FBG) sensor system based on radio-frequency (RF) signal measurement is presented. The RF signal is generated at a photodetector by two modulated optical signals reflected from the sensing FBG and a reference one. Bragg wavelength shift of the sensing FBG changes intensity of the RF signal by changing phase difference between the two optical signals, with temperature effect being compensated automatically by the reference FBG. Strain measurement with a maximum sensitivity of -0.34 μV/με has been achieved.

  17. 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.

  18. Stainless steel component with compressed fiber Bragg grating for high temperature sensing applications

    Science.gov (United States)

    Jinesh, Mathew; MacPherson, William N.; Hand, Duncan P.; Maier, Robert R. J.

    2016-05-01

    A smart metal component having the potential for high temperature strain sensing capability is reported. The stainless steel (SS316) structure is made by selective laser melting (SLM). A fiber Bragg grating (FBG) is embedded in to a 3D printed U-groove by high temperature brazing using a silver based alloy, achieving an axial FBG compression of 13 millistrain at room temperature. Initial results shows that the test component can be used for up to 700°C for sensing applications.

  19. 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.

  20. Temporal transformation of periodic incoherent ultrashort light pulses by chirped fiber gratings.

    Science.gov (United States)

    Zalvidea, Dobryna; Duchowicz, Ricardo; Sicre, Enrique E

    2004-05-20

    The analogy between free-space propagation of optical beams and light-pulse reflection from linearly chirped fiber gratings is used to analyze the Lau effect in the temporal domain. The coherence conditions that are satisfied in the spatial domain for obtaining, at certain fixed locations, periodic fringes patterns are reformulated for guided light propagation. In this analogy, spatial periodic irradiance distributions are transformed in periodic sequences of light pulses. An optical setup is proposed to produce sharp pulse trains, with minimal distortion effects, that have repetition frequencies that are different from those associated with the input periodic optical signal. Some numerical results are given to illustrate this approach.

  1. Design of the target type flowmeter based on fiber Bragg grating and experiment

    Institute of Scientific and Technical Information of China (English)

    Xueguang Qiao; Qian Zhang; Haiwei Fu; Dakuan Yu

    2008-01-01

    The target type flowmeter based on fiber Bragg gratings (FBGs) is experimentally studied. The relationship between the central wavelength shift of FBG and the flux is derived and the analytic expression is also given. Simulation and preliminary experiments have been carried out, and experimental validation of the water further proves the feasibility of the sensor. The experimental results veri .fy the proposed sensor which can measure flux range from 200 to 1200 cm3/s. And on this basis, the improvement program is raised.

  2. 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.

  3. Simulation of path delay multiplexing-based Fourier transform spectrometer for fiber Bragg grating interrogation.

    Science.gov (United States)

    Chelliah, Pandian; Sahoo, Trilochan; Singh, Sheela; Sujatha, Annie

    2015-10-20

    A Fourier transform spectrometer (FTS) used for interrogating a fiber Bragg grating (FBG) consists of a scanning-type interferometer. The FTS has a broad wavelength range of operation and good multiplexing capability. However, it has poor wavelength resolution and interrogation speed. We propose a modification to the FTS using path delay multiplexing to improve the same. Using this method, spatial resolution and interrogation time can be improved by n times by using n path delays. In this paper, simulation results for n=2, 5 are shown.

  4. 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.

  5. Fiber Bragg gratings strain measuring system and a sensor calibration setup based on mechanical nanomotion transducer

    Science.gov (United States)

    Lazarev, Vladimir A.; Leonov, Stanislav O.; Tarabrin, Mikhail K.; Karasik, Valerii E.

    2017-06-01

    Fiber Bragg grating (FBG) strain sensors are powerful tools for structural health monitoring applications. However, FBG sensor fabrication and packaging processes can lead to a non-linear behavior, that affects the accuracy of the strain measurements. Here we present a novel nondestructive calibration technique for FBG strain sensors that use a mechanical nanomotion transducer. A customized calibration setup was designed based on dovetail-type slideways that were mechanized using a stepping motor. The performance of the FBG strain sensor was investigated through analysis of experimental data, and the calibration curves for the FBG strain sensor are presented.

  6. Transmission spectra of coated phase shifted long-period fiber gratings

    Institute of Scientific and Technical Information of China (English)

    GU Zheng-tian; ZHAO Xiao-yun; ZHANG Jiang-tao

    2009-01-01

    The transmission spectrum of the coated phase-shifted long-period fiber gratings (LPFGs) with single and multiple phase shifts is analyzed by the coupled-mode theory and the transfer matrix method, and the influences of the film parameters on the spectral characteristics are also studied. It is shown that these parameters will affect the LPFG filtering characteristics. The loss peak of transmission spectrum decreases with the increase of film thickness, and the peak position shifts with the film refractive index. Compared with the non-coated phase-shifted LPFG, the coated one has the similar desirable filtering characteristics, and it has a flexile ability to adjust the transmission properties.

  7. Distributed acoustic sensing system using an identical weak fiber Bragg grating array

    Science.gov (United States)

    Liu, Sheng; Han, Xinying; Wen, Hongqiao

    2016-10-01

    We propose and experimentally demonstrate a distributed acoustic sensing system using an identical weak fiber Bragg grating array. Phase, frequency and location information of vibration can be demodulated by using a path-match interferometry method. 3×3 coupler demodulation technique is employed to eliminate signal fading in interferometer. Experiments on detecting acoustic wave generated by PZT show that the system is capable of measuring vibrations of up to 1000 Hz over 1.6 km with 2.5m spatial resolution.

  8. Low-cost vibration sensor based on dual fiber Bragg gratings and light intensity measurement.

    Science.gov (United States)

    Gao, Xueqing; Wang, Yongjiao; Yuan, Bo; Yuan, Yinquan; Dai, Yawen; Xu, Gang

    2013-09-20

    A vibration monitoring system based on light intensity measurement has been constructed, and the designed accelerometer is based on steel cantilever frame and dual fiber Bragg gratings (FBGs). By using numerical simulations for the dual FBGs, the dependence relationship of the area of main lobes on the difference of initial central wavelengths is obtained and the most optimal choice for the initial value and the vibration amplitude of the difference of central wavelengths of two FBGs is suggested. The vibration monitoring experiments are finished, and the measured data are identical to the simulated results.

  9. Simultaneous high bit-rate format and mode conversion with a single tilted apodized few-mode fiber Bragg grating

    Science.gov (United States)

    Gao, Ya; Sun, Junqiang; Sima, Chaotan

    2016-10-01

    We propose an all-optical approach for simultaneous high bit-rate return-to-zero (RZ) to non-return-to-zero (NRZ) format and LP01 to LP11 mode conversion using a weakly tilted apodized few-mode fiber Bragg grating (TA-FM-FBG) with specific linear spectral response. The grating apodization profile is designed by utilizing an efficient inverse scattering algorithm and the maximum refractive index modulation is adjusted based on the grating tilt angle, according to Coupled-Mode Theory. The temporal performance and operation bandwidth of the converter are discussed. The approach provides potential favorable device for the connection of various communication systems.

  10. Dual-wavelength single-longitudinal-mode erbium-doped fiber laser based on inverse-Gaussian apodized fiber Bragg grating and its application in microwave generation

    Science.gov (United States)

    Lin, Bo; Tjin, Swee Chuan; Zhang, Han; Tang, Dingyuan; Liang, Sheng; Hao, Jianzhong; Dong, Bo

    2011-03-01

    We propose a simple erbium-doped fiber ring laser. It consists of an inverse-Gaussian apodized fiber Bragg grating filter which has two ultra-narrow transmission bands, and an unpumped erbium-doped fiber as a saturable absorber. Stable dual-wavelength single-longitudinal-mode lasing with a wavelength separation of approximately 0.082 nm is achieved. A microwave signal at 10.502 GHz is demonstrated by beating the dual wavelengths at a photodetector.

  11. Micro-structured fiber Bragg gratings: optimization of the fabrication process.

    Science.gov (United States)

    Iadicicco, A; Campopiano, S; Paladino, D; Cutolo, A; Cusano, A

    2007-11-12

    This work has been devoted to present and demonstrate a novel approach for the fabrication of micro-structured fiber Bragg gratings (MSFBGs) with enhanced control of the geometric features and thus of the spectral properties of the final device. The investigated structure relies on the localized stripping of the cladding layer in a well defined region in the middle of the grating structure leading to the formation of a defect state in the spectral response. In order to fully explore the versatility of MSFBGs for sensing and communications applications, a technological assessment of the fabrication process aimed to provide high control of the geometrical features is required. To this aim, here, we demonstrate that the optimization of this device is possible by adopting a fabrication process based on polymeric coatings patterned by high resolution UV laser micromachining tools. The function of the polymeric coating is to act as mask for the HF based chemical etching process responsible for the cladding stripping. Whereas, UV laser micromachining provides a valuable method to accurately pattern the polymeric coating and thus obtain a selective stripping along the grating structure. Here, we experimentally demonstrate the potentiality of the proposed approach to realize reliable and cost efficient MSFBGs enabling the prototyping of advanced photonics devices based on this technology.

  12. Holographic polymer-dispersed liquid crystal Bragg grating integrated inside a solid core photonic crystal fiber

    CERN Document Server

    Zito, Gianluigi

    2013-01-01

    A polymer/liquid crystal-based fiber Bragg grating (PLC-FBG) is fabricated with visible two-beam holography by photo-induced modulation of a pre-polymer/LC solution infiltrated into the hollow channels of a solid core photonic crystal fiber (PCF). The fabrication process and effects related to the photonic bandgap guidance into the infiltrated PCF, and characterization of the PLC-FBG are discussed. Experimental data here presented, demonstrate that the liquid crystal inclusions of the PLC-FBG lead to high thermal and bending sensitivities. The microscopic behavior of the polymer/liquid crystal phase separation inside the PCF capillaries is examined using scanning electron microscopy, while further discussed.

  13. 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.

  14. Pulsed single-photon spectrograph by frequency-to-time mapping using chirped fiber Bragg gratings

    CERN Document Server

    Davis, Alex O C; Karpinski, Michal; Smith, Brian J

    2016-01-01

    A fiber-integrated spectrograph for single-photon pulses based upon frequency-to-time mapping, implemented by chromatic group delay dispersion (GDD), and precise temporally-resolved single photon counting is presented. A chirped fiber Bragg grating provides low-loss GDD mapping the frequency distribution of an input pulse onto the temporal envelope of the output pulse. Time-resolved detection with fast single-photon-counting modules enables the monitoring of the 825 nm to 835 nm wavelength range with nearly uniform efficiency with 55 pm resolution (24 GHz at 830 nm). To demonstrate the versatility of this technique spectral interference of heralded single photons and the joint spectral intensity distribution of a photon-pair source are measured. This approach to single-photon-level spectral measurements provides a route to realize applications of time-frequency quantum optics at visible and near-infrared wavelengths, where multiple spectral channels must be simultaneously monitored.

  15. Fiber Bragg Grating Sensor for Detection of Nitrate Concentration in Water

    Directory of Open Access Journals (Sweden)

    A. S. LALASANGI

    2011-02-01

    Full Text Available The concentrations of chemical species in drinking water are of great interest. We demonstrated etched fiber Bragg grating (FBG as a concentration sensor for nitrate by analyzing the Bragg wavelength shift with concentration of chemical solution. The FBG is fabricated by phase mask technique on single mode Ge-B co-doped photosensitive fiber. Sensitivity of FBGs to the surrounding solution concentration can be enhanced by reducing diameter of the cladding with 40 % HF solution. The maximum sensitivity achieved is 1.322 ´ 10-3 nm/ppm. The overall shift of Bragg wavelength is of the order of 6.611 ´ 10-2 nm for 10 to 50 ppm concentration.

  16. A fiber-integrated optical component fabricated via photopolymerization: Mode-selective grating coupler

    Science.gov (United States)

    Sümer, Can; Dinleyici, M. Salih

    2013-11-01

    We demonstrate a mode-selective directional coupler based on a grating structure, which is fabricated by laser direct-writing on a photopolymer thin film. The device is implemented on the flat planar surface of the D-Fiber, enabling fiber integration, where an Acrylamide/Polyvinyl Alcohol based photopolymer material is used in the fabrication of the device. While the refractive index modulation properties of the polymer material are well known, surface relief and corrugation properties due to photopolymerization are investigated in this study. Theoretical model of the device is presented together with the optimization and simulation results of the final device; experimental results have been found to be in good agreement with simulations.

  17. 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.

  18. Optical Sensor of Thermal Gas Flow Based on Fiber Bragg Grating

    Science.gov (United States)

    Jiang, Xu; Wang, Keda; Li, Junqing; Zhan, Hui; Song, Zhenan; Che, Guohang; Lyu, Guohui

    2017-01-01

    This paper aims at solving the problem of explosion proof in measurement of thermal gas flow using electronic sensor by presenting a new type of flow sensor by optical fiber heating. A measuring unit based on fiber Bragg grating (FBG) for fluid temperature and a unit for heat dissipation are designed to replace the traditional electronic sensors. The light in C band from the amplified spontaneous emission (ASE) light source is split, with one part used to heat the absorbing coating and the other part used in the signal processing unit. In the heating unit, an absorbing coating is introduced to replace the traditional resistance heating module to minimize the risk of explosion. The measurement results demonstrate a fine consistency between the flow and temperature difference in simulation. The method to enhance the measurement resolution of flow is also discussed. PMID:28212268

  19. Optical Sensor of Thermal Gas Flow Based on Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Xu Jiang

    2017-02-01

    Full Text Available This paper aims at solving the problem of explosion proof in measurement of thermal gas flow using electronic sensor by presenting a new type of flow sensor by optical fiber heating. A measuring unit based on fiber Bragg grating (FBG for fluid temperature and a unit for heat dissipation are designed to replace the traditional electronic sensors. The light in C band from the amplified spontaneous emission (ASE light source is split, with one part used to heat the absorbing coating and the other part used in the signal processing unit. In the heating unit, an absorbing coating is introduced to replace the traditional resistance heating module to minimize the risk of explosion. The measurement results demonstrate a fine consistency between the flow and temperature difference in simulation. The method to enhance the measurement resolution of flow is also discussed.

  20. pH-responsive hydrogel coated fiber Bragg grating-based chemo mechanical sensor bioreactor applications

    Science.gov (United States)

    Kishore, P. V. N.; Sai Shankar, M.

    2017-04-01

    This paper describes a fiber optics based pH sensor by using wavelength modulated techniques. Fiber Bragg grating (FBG) is functionalized with a stimulus responsive hydrogel which 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 which is monitored by an interrogator. The sensor system shows a good linearity in acidic pH range of 3 to 7 with a sensitivity of 12.16pm/pH. Besides that it shows good repeatability which proves it to be fit for pH sensing applications.

  1. Temperature profile of ex-vivo organs during radio frequency thermal ablation by fiber Bragg gratings

    Science.gov (United States)

    Palumbo, Giovanna; Iadicicco, Agostino; Tosi, Daniele; Verze, Paolo; Carlomagno, Nicola; Tammaro, Vincenzo; Ippolito, Juliet; Campopiano, Stefania

    2016-11-01

    We report on the integration of fiber optic sensors with commercial medical instrumentation for temperature monitoring during radio frequency ablation for tumor treatment. A suitable configuration with five fiber Bragg grating sensors bonded to a bipolar radio frequency (RF) probe has been developed to monitor the area under treatment. A series of experiments were conducted on ex-vivo animal kidney and liver and the results confirm that we were able to make a multipoint measurement and to develop a real-time temperature profile of the area, with a temperature resolution of 0.1°C and a spatial resolution of 5 mm during a series of different and consecutive RF discharges.

  2. An Architecture for Measuring Joint Angles Using a Long Period Fiber Grating-Based Sensor

    Directory of Open Access Journals (Sweden)

    Carlos A. Perez-Ramirez

    2014-12-01

    Full Text Available The implementation of signal filters in a real-time form requires a tradeoff between computation resources and the system performance. Therefore, taking advantage of low lag response and the reduced consumption of resources, in this article, the Recursive Least Square (RLS algorithm is used to filter a signal acquired from a fiber-optics-based sensor. In particular, a Long-Period Fiber Grating (LPFG sensor is used to measure the bending movement of a finger. After that, the Gaussian Mixture Model (GMM technique allows us to classify the corresponding finger position along the motion range. For these measures to help in the development of an autonomous robotic hand, the proposed technique can be straightforwardly implemented on real time platforms such as Field Programmable Gate Array (FPGA or Digital Signal Processors (DSP. Different angle measurements of the finger’s motion are carried out by the prototype and a detailed analysis of the system performance is presented.

  3. Fiber curvature sensor based on spherical-shape structures and long-period grating

    Science.gov (United States)

    Xiong, Mengling; Gong, Huaping; Wang, Zhiping; Zhao, Chun-Liu; Dong, Xinyong

    2016-11-01

    A novel curvature sensor based on optical fiber Mach-Zehnder interferometer (MZI) is demonstrated. It consists of two spherical-shape structures and a long-period grating (LPG) in between. The experimental results show that the shift of the dip wavelength is almost linearly proportional to the change of curvature, and the curvature sensitivity are -22.144 nm/m-1 in the measurement range of 5.33-6.93 m-1, -28.225 nm/m-1 in the range of 6.93-8.43 m- and -15.68 nm/m-1 in the range of 8.43-9.43 m-1, respectively. And the maximum curvature error caused by temperature is only -0.003 m-1/°C. The sensor exhibits the advantages of all-fiber structure, high mechanical strength, high curvature sensitivity and large measurement scales.

  4. 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.

  5. 光纤布拉格光栅应变花%Fiber Bragg Grating Strain Rosette

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper a Fiber Bragg Grating (FBG) Strain Rosette is designed, developed and tested. Traditional FBGs measure strain in only one direction. However, in-plane strain at a point consists of two normal strains and one shear strain. Hence a FBG strain rosette needs to be designed. The sensing principle of FBGs as a strain and temperature sensor and fundamental principles of strain transformation and strain gage rosettes are discussed.FBG strain rosettes are fabricated and embedded in two materials namely, Silicon Gel RTV 146-9 and Glass Fiber Composite Laminates. Experiments were conducted on the FBG strain rosette structures that were embedded in Silicon Gel (RTV 146-9). Initial findings from the experiments as well as preferred embedding material are presented.

  6. Creation of a microstructured polymer optical fiber with UV Bragg grating inscription for the detection of extensions at temperatures up to 125°C

    DEFF Research Database (Denmark)

    Fasano, Andrea; Woyessa, Getinet; Stajanca, Pavol

    2016-01-01

    We describe the fabrication of a polycarbonate (PC) micro-structured polymer optical fiber (mPOF) and the writing offiber Bragg gratings (FBGs) in it to enable strain and temperature measurements. We demonstrate the photosensitivity ofa dopant-free PC fiber by grating inscription using a UV laser...

  7. [The experiment research on solution refractive index sensor based on tilted fiber Bragg grating].

    Science.gov (United States)

    Jiang, Qi; Lü, Dan-Dan; Yu, Ming-Hao; Kang, Li-Min; Ouyang, Jun

    2013-12-01

    The present paper analyzes the sensor's basic principle of the bare tilted fiber Bragg grating (TFBG) and surface plasmon resonance sensor (SPR) that deposited nanoscale gold-coating on the surface of the cladding. We simulated the transmission spectrums and some order cladding mode of TFBG in different concentration solutions by Integration and optical fiber grating software OptiGrating. So by the graphic observation and data analysis, a preliminary conclusion was got that in a certain sensing scope, the cladding modes of TFBG shift slightly to right with the increasing the solution refractive index(SRI),and the relation between resonance peak caused by the coupling of core mode and a certain cladding mode and the SRI was linear. Then the 45 nm thick gold coating was deposited on the surface of the TFBG cladding in a small-scale sputtering chamber KYKY SBC-12, and thermal field scanning electron microscopy presents that the effect of gold-coating was satisfactory to a certain extent in terms of microscopic level. The refractive index(RI) sensing experiments of different concentration solutions of NaCI, MgCI2, CaCI2 were carried out using bare and gold deposited TFBG. The RI sensing characteristics of both bare and gold deposited TFBGs respectively were studied by experiments. Meanwhile, it proved the conclusion that the cladding modes of TFBG drifted to right gradually when the SRI was increasing and the relations between resonance peak caused by the coupling of core mode and a certain cladding mode and the SRI were linear. And by quantitative analysis, we know that SPR sensor with the deposited namoscale gold layer on the surface of cladding enhanced the RI sensitivity dramatically by 2 to 500 nm RIU-1 which is 200 to 300 times larger than that of the bare tilted fiber Bragg grating approximately. The degrees of linear fittings of resonance peak caused by the coupling of core mode and a certain cladding mode and SRI of bare and gold-coating deposited SPR sensor

  8. 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

  9. 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.

  10. Towards a Uniform Metrological Assessment of Grating-Based Optical Fiber Sensors: From Refractometers to Biosensors.

    Science.gov (United States)

    Chiavaioli, Francesco; Gouveia, Carlos A J; Jorge, Pedro A S; Baldini, Francesco

    2017-06-21

    A metrological assessment of grating-based optical fiber sensors is proposed with the aim of providing an objective evaluation of the performance of this sensor category. Attention was focused on the most common parameters, used to describe the performance of both optical refractometers and biosensors, which encompassed sensitivity, with a distinction between volume or bulk sensitivity and surface sensitivity, resolution, response time, limit of detection, specificity (or selectivity), reusability (or regenerability) and some other parameters of generic interest, such as measurement uncertainty, accuracy, precision, stability, drift, repeatability and reproducibility. Clearly, the concepts discussed here can also be applied to any resonance-based sensor, thus providing the basis for an easier and direct performance comparison of a great number of sensors published in the literature up to now. In addition, common mistakes present in the literature made for the evaluation of sensor performance are highlighted, and lastly a uniform performance assessment is discussed and provided. Finally, some design strategies will be proposed to develop a grating-based optical fiber sensing scheme with improved performance.

  11. 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.

  12. Cladding mode coupling in long-period gratings in index-guided microstructured optical fibers

    Science.gov (United States)

    Sharma, Dinesh Kumar; Sharma, Anurag; Tripathi, Saurabh Mani

    2017-06-01

    To inscribe the long-period gratings (LPGs) in an index-guiding (or the solid-core) microstructured optical fiber (MOF), the opto-geometrical parameters of the fiber have to be determined, at first. Using our earlier developed analytical field model, we have evaluated the effective index for the fundamental core mode of the triangular lattice-based MOF, and the effective index of the fundamental cladding mode is obtained by approximating hexagonal unit cell by a circular unit cell. We demonstrate that the grating period of the LPGs obtained using the radius of the equivalent circular unit cell of Λ/2 and Λ ( {{{√ 3 } {2π } )^{1/2}, which are the two widely accepted radii for evaluating the effective index of the fundamental cladding mode, do not match well with the available experimental results. Therefore, to achieve better agreement in the results, we have proposed the linear combination of these two radii. Comparisons with available experimental results have also been included.

  13. 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.

  14. High-efficiency Q-switched erbium fiber laser using a Bragg grating-based modulator

    Science.gov (United States)

    Russo, N. A.; Duchowicz, R.; Mora, J.; Cruz, J. L.; Andrés, M. V.

    2002-09-01

    In this work we analyze the behavior of an erbium-doped fiber laser which is based on a simple scheme. Excitation of the active medium is performed in the 980 nm pump band with a CW semiconductor laser source. Two fiber Bragg gratings acting as mirrors of the Fabry-Perot laser cavity were used. One of these gratings was mounted over a piezoelectric (PZT) element. By applying voltage pulses to the piezoelectric, the laser cavity was temporally modulated and Q-switched laser pulses up to 530 mW peak powers at 3 kHz were obtained. Typical laser emission of 2-3 μs temporal widths and 0.1 nm of optical bandwidth have been achieved when the system was operated at 18.5 kHz repetition rates. Different behaviors were observed depending on the pumping level of the active medium and on the amplitude and frequency of the signal applied on the PZT. Q-switched laser output, in the erbium spectral gain region, with high laser efficiency of energy conversion was generated. Pumping at 76 mW and operating the laser at 18.5 kHz, an efficiency of 26% was obtained.

  15. A New Type of Absorbance Sensors Based on Long-Period Fiber Gratings

    Institute of Scientific and Technical Information of China (English)

    LUO Tao; GU Zheng-Tian

    2011-01-01

    @@ A new absorbance sensor based on long-period fiber gratings(LPFGs) is presented,The measurand is coated on the cladding of the LPFG.It is found that the depth of the stop band of the LPFG spectrum will be strongly affected by the absorbance of the measurand if an optimum coating thickness is selected.The analysis showsthat within the optimal thickness range,the cladding modes could transform into the overlay modes and interact with the measurand more effectively.An absorbance sensitivity of 7 × 103 is available when the sensor structure is optimized.%A new absorbance sensor based on long-period fiber gratings (LPFGs) is presented, The measurand is coated on the cladding of the LPFG. It is found that the depth of the stop band of the LPFG spectrum will be strongly affected by the absorbance of the measurand if an optimum coating thickness is selected. The analysis shows that within the optimal thickness range, the cladding modes could transform into the overlay modes and interact with the measurand more effectively. An absorbance sensitivity of 7 × 103 is available when the sensor structure is optimized.

  16. Bare fiber Bragg grating immunosensor for real-time detection of Escherichia coli bacteria.

    Science.gov (United States)

    Srinivasan, Rajesh; Umesh, Sharath; Murali, Swetha; Asokan, Sundarrajan; Siva Gorthi, Sai

    2017-02-01

    Escherichia coli (E. coli) bacteria have been identified to be the cause of variety of health outbreaks resulting from contamination of food and water. Timely and rapid detection of the bacteria is thus crucial to maintain desired quality of food products and water resources. A novel methodology proposed in this paper demonstrates for the first time, the feasibility of employing a bare fiber Bragg grating (bFBG) sensor for detection of E. coli bacteria. The sensor was fabricated in a photo-sensitive optical fiber (4.2 µm/80 µm). Anti-E. coli antibody was immobilized on the sensor surface to enable the capture of target cells/bacteria present in the sample solution. Strain induced on the sensor surface as a result of antibody immobilization and subsequent binding of E. coli bacteria resulted in unique wavelength shifts in the respective recording of the reflected Bragg wavelength, which can be exploited for the application of biosensing. Functionalization and antibody binding on to the fiber surface was cross validated by the color development resulting from the reaction of an appropriate substrate solution with the enzyme label conjugated to the anti-E. coli antibody. Scanning electron microscope image of the fiber, further verified the E. coli cells bound to the antibody immobilized sensor surface. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Elimination of drift in a fiber-Bragg-grating-based multiplexed Michelson interferometer measurement system.

    Science.gov (United States)

    Ren, Junyu; Xie, Fang; Chen, Zhimin

    2010-02-01

    Random phase drift in single-mode optical fiber interferometers used with measurement systems, which is resulted from various types of environmental disturbances, should be eliminated in order to obtain high measurement precision. We propose an optical fiber interferometric measurement system which has the function of self-eliminating the random phase drift and is stable and robust enough for real-time precision measurement. By employing the characteristics of fiber Bragg gratings, the system interleaves two fiber Michelson interferometers together that share the common-interferometric-optical path. The signal of one of the interferometers is used to stabilize the system while the signal of the other interferometer is used for measurement. An electronic feedback loop for the stabilizing action is designed. The bandwidth of the feedback loop is 5 kHz, sufficiently wide to eliminate random phase drift resulted from various environmental disturbances. The system is endowed with high stability and therefore suitable for real-time precision measurement. By means of an active phase tracking technique to measure displacement, the linear regression coefficient of the displacement measurement results is 0.9998.

  18. Elimination of drift in a fiber-Bragg-grating-based multiplexed Michelson interferometer measurement system

    Energy Technology Data Exchange (ETDEWEB)

    Ren Junyu; Xie Fang; Chen Zhimin [Department of Physics, School of Science, Beijing Jiaotong University, Beijing 100044 (China)

    2010-02-15

    Random phase drift in single-mode optical fiber interferometers used with measurement systems, which is resulted from various types of environmental disturbances, should be eliminated in order to obtain high measurement precision. We propose an optical fiber interferometric measurement system which has the function of self-eliminating the random phase drift and is stable and robust enough for real-time precision measurement. By employing the characteristics of fiber Bragg gratings, the system interleaves two fiber Michelson interferometers together that share the common-interferometric-optical path. The signal of one of the interferometers is used to stabilize the system while the signal of the other interferometer is used for measurement. An electronic feedback loop for the stabilizing action is designed. The bandwidth of the feedback loop is 5 kHz, sufficiently wide to eliminate random phase drift resulted from various environmental disturbances. The system is endowed with high stability and therefore suitable for real-time precision measurement. By means of an active phase tracking technique to measure displacement, the linear regression coefficient of the displacement measurement results is 0.9998.

  19. Elimination of drift in a fiber-Bragg-grating-based multiplexed Michelson interferometer measurement system

    Science.gov (United States)

    Ren, Junyu; Xie, Fang; Chen, Zhimin

    2010-02-01

    Random phase drift in single-mode optical fiber interferometers used with measurement systems, which is resulted from various types of environmental disturbances, should be eliminated in order to obtain high measurement precision. We propose an optical fiber interferometric measurement system which has the function of self-eliminating the random phase drift and is stable and robust enough for real-time precision measurement. By employing the characteristics of fiber Bragg gratings, the system interleaves two fiber Michelson interferometers together that share the common-interferometric-optical path. The signal of one of the interferometers is used to stabilize the system while the signal of the other interferometer is used for measurement. An electronic feedback loop for the stabilizing action is designed. The bandwidth of the feedback loop is 5 kHz, sufficiently wide to eliminate random phase drift resulted from various environmental disturbances. The system is endowed with high stability and therefore suitable for real-time precision measurement. By means of an active phase tracking technique to measure displacement, the linear regression coefficient of the displacement measurement results is 0.9998.

  20. Increasing signal amplitude in fiber Bragg grating detection of Lamb waves using remote bonding.

    Science.gov (United States)

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

    2016-07-20

    Networks of fiber Bragg grating (FBG) sensors can serve as structural health monitoring systems for large-scale structures based on the collection of ultrasonic waves. The demodulation of structural Lamb waves using FBG sensors requires a high signal-to-noise ratio because the Lamb waves are of low amplitudes. This paper compares the signal transfer amplitudes between two adhesive mounting configurations for an FBG to detect Lamb waves propagating in an aluminum plate: a directly bonded FBG and a remotely bonded FBG. In the directly bonded FBG case, the Lamb waves create in-plane and out-of-plane displacements, which are transferred through the adhesive bond and detected by the FBG sensor. In the remotely bonded FBG case, the Lamb waves are converted into longitudinal and flexural traveling waves in the optical fiber at the adhesive bond, which propagate through the optical fiber and are detected by the FBG sensor. A theoretical prediction of overall signal attenuation also is performed, which is the combination of material attenuation in the plate and optical fiber and attenuation due to wave spreading in the plate. The experimental results demonstrate that remote bonding of the FBG significantly increases the signal amplitude measured by the FBG.

  1. Near-infrared grating-assisted SPR optical fiber sensors: design rules for ultimate refractometric sensitivity.

    Science.gov (United States)

    Caucheteur, Christophe; Voisin, Valérie; Albert, Jacques

    2015-02-09

    Plasmonic optical fiber sensors are continuously developed for (bio)chemical sensing purposes. Recently, surface plasmon resonance (SPR) generation was achieved in gold-coated tilted fiber Bragg gratings (TFBGs). These sensors probe the surrounding medium with near-infrared narrowband resonances, which enhances both the penetration depth of the evanescent field in the external medium and the wavelength resolution of the interrogation. They constitute a unique configuration to probe all the fiber cladding modes individually. We use them to analyze the modal distribution of gold-coated telecommunication-grade optical fibers immersed in aqueous solutions. Theoretical investigations with a finite-difference complex mode solver are confirmed by experimental data obtained on TFBGs. We show that the refractometric sensitivity varies with the mode order and that the global SPR envelope shift in response to surrounding refractive index (SRI) changes higher than 1e-2 RIU (refractive index unit) can be ~25% bigger than the local SPR mode shift arising from SRI changes limited to 1e-4 RIU. We bring clear evidence that the optimum gold thickness for SPR generation lies in the range between 50 and 70 nm while a cladding diameter decrease from 125 µm to 80 µm enhances the refractometric sensitivity by ~20%. Finally, we demonstrate that the ultimate refractometric sensitivity of cladding modes is ~550 nm/RIU when they are probed by gold-coated TFBGs.

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

    Science.gov (United States)

    Li, Tianliang; Tan, Yuegang; Zhou, Zude

    2016-04-15

    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.

  3. Optic fiber hydrogen sensor based on high-low reflectivity Bragg gratings and WO3-Pd-Pt multilayer films

    Science.gov (United States)

    Dai, Jixiang; Yang, Minghong; Li, Zhi; Wang, Gaopeng; Huang, Chujia; Qi, Chongjie; Dai, Yutang; Wen, Xiaoyan; Cheng, Cheng; Guo, Huiyong

    2015-09-01

    A novel optic fiber hydrogen sensor is proposed in this paper. Two Bragg gratings with different reflectivity were written in single mode fiber with phase mask method by 248 nm excimer laser. The end-face of singe mode fiber was deposited with WO3-Pd-Pt multilayer films as sensing element. The peak intensity of low reflectivity FBG is employed for hydrogen characterization, while that of high reflectivity FBG is used as reference. The experimental results show the hydrogen sensor still has good repeatability when the optic intensity in the fiber is only 1/3 of its initial value. The hydrogen sensor has great potential in measurement of hydrogen concentration.

  4. Optimization and efficient routing scenario of system using C-band: reconfigurable multiwavelength optical cross connect based on tunable fiber Bragg grating and optical circulator

    Science.gov (United States)

    Singh, Manpreet; Dewra, Sanjeev; Kaler, Rajinder S.

    2016-07-01

    The impact of physical parameters such as grating length, effective index of grating, and apodization on the performance of 5×5 reconfigurable multiwavelength optical cross connect based on tunable fiber Bragg grating and optical circulator in DWDM system with 0.8-nm channel spacing at 15×10 Gbps is evaluated. It is observed that least BER is achieved at the minimum input transmission power with specific values of grating length, effective index of grating, and apodization change of a T-FBG. It shows that BER increases as the values of T-FBG grating length, effective index of grating, and apodization decrease. The data can be transmitted over a distance of 60 km in the presence of fiber nonlinearities without optical amplifier and dispersion compensating techniques.

  5. 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.

  6. Corrosion detection of steel reinforced concrete using combined carbon fiber and fiber Bragg grating active thermal probe

    Science.gov (United States)

    Li, Weijie; Ho, Siu Chun Michael; Song, Gangbing

    2016-04-01

    Steel reinforcement corrosion is one of the dominant causes for structural deterioration for reinforced concrete structures. This paper presents a novel corrosion detection technique using an active thermal probe. The technique takes advantage of the fact that corrosion products have poor thermal conductivity, which will impede heat propagation generated from the active thermal probe. At the same time, the active thermal probe records the temperature response. The presence of corrosion products can thus be detected by analyzing the temperature response after the injection of heat at the reinforcement-concrete interface. The feasibility of the proposed technique was firstly analyzed through analytical modeling and finite element simulation. The active thermal probe consisted of carbon fiber strands to generate heat and a fiber optic Bragg grating (FBG) temperature sensor. Carbon fiber strands are used due to their corrosion resistance. Wet-dry cycle accelerated corrosion experiments were performed to study the effect of corrosion products on the temperature response of the reinforced concrete sample. Results suggest a high correlation between corrosion severity and magnitude of the temperature response. The technique has the merits of high accuracy, high efficiency in measurement and excellent embeddability.

  7. Single-polarization, switchable dual-wavelength erbium-doped fiber laser with two polarization-maintaining fiber Bragg gratings.

    Science.gov (United States)

    Feng, Suchun; Xu, Ou; Lu, Shaohua; Mao, Xiangqiao; Ning, Tigang; Jian, Shuisheng

    2008-08-04

    An improved erbium-doped fiber laser configuration for achieving single-polarization, switchable dual-wavelength of orthogonal polarizations oscillations at room temperature is proposed. For the first time, two fiber Bragg gratings (FBGs) directly written in a polarization-maintaining (PM) and photosensitive erbium-doped fiber (PMPEDF) as the wavelength-selective component are used in a linear laser cavity. Due to the polarization hole burning (PHB) enhanced by the polarization-maintaining FBG (PMFBG), the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). Each lasing line shows a single polarization with a polarization extinction ratio of >25 dB under different pump levels. The optical signal-to-noise ratio (OSNR) is greater than 50 dB. The amplitude variation with 16 times scans in nearly one and half an hour is less than 0.5 dB at both operating wavelength.

  8. 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...

  9. Method of correlation function for analyzing cross-sensitivity of strain and temperature in fiber grating sensors

    Institute of Scientific and Technical Information of China (English)

    HAN Gui-hua; ZHANG Wei-gang

    2007-01-01

    A novel method of correlation function for analyzing cross-sensitivity between strain and temperature is reported for the first time in this paper. Using the new method, the correlative characteristics between strain and temperature of fiber Bragg grating sensors are studied both theoretically and experimentally The experimental results accord with the theoretical calculations.

  10. Simultaneous measurement of curvature and temperature based on LP 11 mode Bragg grating in seven-core fiber

    Science.gov (United States)

    Zhang, Yunshan; Zhang, Weigang; Zhang, Yanxin; Wang, Song; Yu, Lin; Yan, Yieyi

    2017-05-01

    A robust and compact fiber sensor for simultaneous measurement of curvature and temperature based on LP 11 mode Bragg grating is proposed and demonstrated in this paper. The sensor is formed by splicing a short piece of seven-core fiber (SCF) with Bragg grating to single mode fiber (SMF). The Bragg grating is inscribed by UV light exposure, and mainly LP 01 resonance peak and LP 11 resonance peak are observed in the reflection spectrum. The experimental results show that the wavelength of the LP 11 Bragg resonance is insensitive to curvature but the power is very sensitive to curvature. The curvature sensitivity is  -7.27 dB/m-1 with a linearity of 0.997 in the curvature range of 0-1 m-1. The temperature characteristic shows that the Bragg resonance has almost the same sensitivity as the common fiber Bragg grating (FBG). The sensor is also available to be independent of the ambient refractive index(RI).

  11. Mine operating accurate stability control with optical fiber sensing and Bragg grating technology: the BRITE-EURAM STABILOS project

    Science.gov (United States)

    Ferdinand, Pierre; Ferragu, Olivier; Lechien, J. L.; Lescop, B.; Marty-DeWinter, Veronique; Rougeault, S.; Pierre, Guillaume; Renouf, C.; Jarret, Bertrand; Kotrotsios, Georges; Neuman, Victor; Depeursinge, Y.; Michel, J. B.; Van Uffelen, M.; Verbandt, Yves; Voet, Marc R. H.; Toscano, D.

    1994-09-01

    Recent developments of stability control in mines, essentially based on Ge-doped Fiber Bragg Gratings (FBG) are reported including results about the different aspects of the system: accurate characterizations of FBG, sensor network topology and multiplexing method, user interface design and sensor packaging.

  12. On using an array of fiber bragg grating sensors for closed-loop control of flexible minimally invasive surgical instruments

    NARCIS (Netherlands)

    Roesthuis, Roy; Janssen, Sander; Misra, Sarthak

    2013-01-01

    Flexible minimally invasive surgical instruments can be used to target difficult-to-reach locations within the human body. Accurately steering these instruments requires information about the three-dimensional shape of the instrument. In the current study, we use an array of Fiber Bragg Grating

  13. Full distortion induced by dispersion evaluation and optical bandwidth constraining of fiber Bragg grating demultiplexers over analogue SCM systems.

    Science.gov (United States)

    Martinez, Alfonso; Pastor, Daniel; Capmany, Jose

    2002-12-30

    We provide a full analysis of the distortion effects produced by the first and second order in-band dispersion of fiber Bragg grating based optical demultiplexers over analogue SCM (Sub Carrier Multiplexed) signals. Optical bandwidth utilization ranges for Dense WDM network are calculated considering different SCM system cases of frequency extension and modulation conditions.

  14. Widely tunable LP11 cladding-mode resonance in a twisted mechanically induced long-period fiber grating.

    Science.gov (United States)

    Nair, Anitha S; Sudeep Kumar, V P; Joe, Hubert

    2015-03-10

    A record tunability of 35 nm for the LP(11) cladding-mode resonance in a twisted mechanically induced long-period fiber grating using standard single-mode communication fiber is demonstrated. By forming the LP(11) resonance far away from its cut-off wavelength and modifying the grooves of the grating in the form of smooth semicircular humps, a high twist sensitivity of 8.75 nm/(rad/cm) and a controlled tunability of 35 nm is achieved. The fiber with its lacquer coating is not broken even at a severe twist rate of 5.44 rad/cm. The present design can be used as a novel variable optical selective wavelength attenuator since the bandwidth, rejection efficiency, and center wavelength can be controlled by changing the grating length, pressure over the grating, and fiber twist, respectively. Using the results, a cost-effective tunable variable optical attenuator for selective channel-blanking applications is also demonstrated. A fine tunability of 1.5 nm is achieved for a twist rate change of 0.1 rad/cm.

  15. 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.

  16. Transmissive grating-reflective mirror-based fiber optic accelerometer for stable signal acquisition in industrial applications

    Science.gov (United States)

    Lee, Yeon-Gwan; Kim, Dae-Hyun; Kim, Chun-Gon

    2012-05-01

    This paper discusses an applicable fiber-optic accelerometer composed of a transmissive grating panel, a reflection mirror, and two optical fibers with a separation of quarter grating pitch as transceivers that monitor the low-frequency accelerations of civil engineering structures. This sensor structure brings together the advantages of both a simple sensor structure, which leads to simplified cable design by 50% in comparison with the conventional transmission-type fiber optic accelerometer, and a stable reflected signals acquisition with repeatability in comparison to the researched grating-reflection type fiber optic accelerometer. The vibrating displacement and sinusoidal acceleration measured from the proposed fiber optic sensor demonstrated good agreement with those of a commercial laser displacement sensor and a MEMS accelerometer without electromagnetic interference. The developed fiber optic accelerometer can be used in frequency ranges below 4.0 Hz with a margin of error that is less than 5% and a high sensitivity of 5.06 rad/(m/s)2.

  17. Wavelength control of erbium-doped fiber ring lasers by means of π-shifted variable long-period fiber gratings

    Science.gov (United States)

    Sakata, H.; Ono, Y.; Dodo, S.

    2016-04-01

    In this paper, fiber ring resonators are composed of an erbium-doped fiber amplifier (EDFA) with a π-shifted long-period fiber grating (PS-LPFG) to control the lasing wavelength. The PS-LPFG forms the passband inside the rejection band in the transmission spectrum, and the passband is shifted to longer wavelengths by stretching a coil spring that presses the fiber with an electromagnet. The oscillation wavelength is shifted from 1532.8 to 1565.1 nm depending on the variable grating period by using the C-band EDFA. By replacing to the L-band EDFA, the tunable wavelength range is moved to the range from 1586.8 to 1613.8 nm. The laser emission spectra exhibit the 3 dB spectral bandwidth of ~0.1 nm with a side-mode suppression ratio of ~40 dB.

  18. Software Development to Assist in the Processing and Analysis of Data Obtained Using Fiber Bragg Grating Interrogation Systems

    Science.gov (United States)

    Hicks, Rebecca

    2010-01-01

    A fiber Bragg grating is a portion of a core of a fiber optic stand that has been treated to affect the way light travels through the strand. Light within a certain narrow range of wavelengths will be reflected along the fiber by the grating, while light outside that range will pass through the grating mostly undisturbed. Since the range of wavelengths that can penetrate the grating depends on the grating itself as well as temperature and mechanical strain, fiber Bragg gratings can be used as temperature and strain sensors. This capability, along with the light-weight nature of the fiber optic strands in which the gratings reside, make fiber optic sensors an ideal candidate for flight testing and monitoring in which temperature and wing strain are factors. A team of NASA Dryden engineers has been working to advance the fiber optic sensor technology since the mid 1990 s. The team has been able to improve the dependability and sample rate of fiber optic sensor systems, making them more suitable for real-time wing shape and strain monitoring and capable of rivaling traditional strain gauge sensors in accuracy. The sensor system was recently tested on the Ikhana unmanned aircraft and will be used on the Global Observer unmanned aircraft. Since a fiber Bragg grating sensor can be placed every halfinch on each optic fiber, and since fibers of approximately 40 feet in length each are to be used on the Global Observer, each of these fibers will have approximately 1,000 sensors. A total of 32 fibers are to be placed on the Global Observer aircraft, to be sampled at a rate of about 50 Hz, meaning about 1.6 million data points will be taken every second. The fiber optic sensors system is capable of producing massive amounts of potentially useful data; however, methods to capture, record, and analyze all of this data in a way that makes the information useful to flight test engineers are currently limited. The purpose of this project is to research the availability of software

  19. 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

    and realization of a microstructured polymer optical fiber made of PMMA for direct writing of FBGs. The fiber was designed specifically to avoid obstruction of the writing beam by air-holes. The realized fiber has been used to point-by-point write a 5 mm long fourth order FBG with a Bragg wavelength of 1518 nm...

  20. 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.

  1. 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

    2014-09-29

    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.

  2. 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.

  3. 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.

  4. 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.

  5. Monitoring corrosion of reinforcement in concrete structures via fiber Bragg grating sensors

    Institute of Scientific and Technical Information of China (English)

    Zhupeng ZHENG; Xiaoning SUN; Ying LEI

    2009-01-01

    Corrosion of steel and rebar in concretestructures is one of the most frequent reasons for civil infrastructure failures. Thus, improving the effective corrosion sensor technology can greatly reduce cost and provide safe structures with long service lives. However, assessing the corrosion condition of rebars is not simple because they are buried in concrete. In this paper, using fiber Bragg grating (FBG), a corrosion sensor for monitoring steel rebars embedded in a concrete structure is developed and validated by experiments. Based on the fact that the volume and diameter of a rebar embedded in concrete will enlarge due to corrosion, an FBG packaged with fiber-reinforced plastics (FRP) is wrapped on the steel bar. During corrosion, the increase in the bar diameter leads to the increase in fiber strain, which can be measured by the shift of the wavelength of FBG. Performances of the corrosion sensor are validated by accelerating corrosion in lab experiments. The corrosion sensor is embedded in a concrete specimen put in a 5% sodium chloride solution with a constant current. Experimental results show that the corrosion sensor can monitor the concurrence of corrosion of rebars in concrete. The corrosion extent can be quantitatively evaluated through the change in the wavelength of FBG. Therefore, the corrosion sensor developed in this paper is feasible for monitoring the early corrosion of rebars in concrete.

  6. DNA biosensors implemented on PNA-functionalized microstructured optical fibers Bragg gratings

    Science.gov (United States)

    Candiani, A.; Giannetti, S.; Cucinotta, A.; Bertucci, A.; Manicardi, A.; Konstantaki, M.; Margulis, W.; Pissadakis, S.; Corradini, R.; Selleri, S.

    2013-05-01

    A novel DNA sensing platform based on a Peptide Nucleic Acid - functionalized Microstructured Optical Fibers gratings has been demonstrated. The inner surface of different MOFs has been functionalized using PNA probes, OligoNucleotides mimic that are well suited for specific DNA target sequences detection. The hybrid sensing systems were tested for optical DNA detection of targets of relevance in biomedical application, using the cystic fibrosis gene mutation, and food-analysis, using the genomic DNA from genetic modified organism soy flour. After the solutions of DNA molecules has been infiltrated inside the fibers capillaries and hybridization has occurred, oligonucleotidefunctionalized gold nanoparticles were infiltrated and used to form a sandwich-like system to achieve signal amplification. Spectral measurements of the reflected signal reveal a clear wavelength shift of the reflected modes when the infiltrated complementary DNA matches with the PNA probes placed on the inner fiber surface. Measurements have also been made using the mismatched DNA solution for the c, containing a single nucleotide polymorphism, showing no significant changes in the reflected spectrum. Several experiments have been carried out demonstrating the reproducibility of the results and the high selectivity of the sensors, showing the simplicity and the potential of this approach.

  7. 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.

  8. PARAFAC Decomposition for Ultrasonic Wave Sensing of Fiber Bragg Grating Sensors: Procedure and Evaluation

    Directory of Open Access Journals (Sweden)

    Rencheng Zheng

    2015-07-01

    Full Text Available Ultrasonic wave-sensing technology has been applied for the health monitoring of composite structures, using normal fiber Bragg grating (FBG sensors with a high-speed wavelength interrogation system of arrayed waveguide grating (AWG filters; however, researchers are required to average thousands of repeated measurements to distinguish significant signals. To resolve this bottleneck problem, this study established a signal-processing strategy that improves the signal-to-noise ratio for the one-time measured signal of ultrasonic waves, by application of parallel factor analysis (PARAFAC technology that produces unique multiway decomposition without additional orthogonal or independent constraints. Through bandpass processing of the AWG filter and complex wavelet transforms, ultrasonic wave signals are preprocessed as time, phase, and frequency profiles, and then decomposed into a series of conceptual three-way atoms by PARAFAC. While an ultrasonic wave results in a Bragg wavelength shift, antiphase fluctuations can be observed at two adjacent AWG ports. Thereby, concentrating on antiphase features among the three-way atoms, a fitting atom can be chosen and then restored to three-way profiles as a final result. An experimental study has revealed that the final result is consistent with the conventional 1024-data averaging signal, and relative error evaluation has indicated that the signal-to-noise ratio of ultrasonic waves can be significantly improved.

  9. Compact microfluidic sensing by introducing effective phase shift in fiber Bragg grating

    Science.gov (United States)

    Tang, Minghui; Wang, Guanghui; Ho, Ho-Pui A.; Zhang, Xuping

    2014-10-01

    A compact microfluidic refractive index sensor fabricated by drilling hole in the middle section of a fiber Bragg grating (FBG) is reported herein. The laser-drilled hole provides a microfluidic channel for the aqueous sample to pass through while at the same time permits coupling of the interrogating light to detect the target analyte. The reported sensor takes advantage of the fact that a small phase shift in the central region of the grating will result in a very sharp peak in the FBG stop-band. The phase shift can be related to a range of possible perturbations inside the microfluidic channel, including passage of cells, beads and a shift in the concentration of certain fluidic component. The amount of wavelength shift of the peak in the FBG stop-band represents the change in the refractive index inside the microfluidic channel. Simulation results indicate very favorable sensor signal characteristics such as large wavelength shift and sharp reflection dips. The reported microfluidic phase shift FGB sensor could be a good candidate for portable flow cytometry applications.

  10. Watts-level super-compact narrow-linewidth Tm-doped silica all-fiber laser near 1707 nm with fiber Bragg gratings

    Science.gov (United States)

    Xiao, X. S.; Guo, H. T.; Lu, M.; Yan, Z. J.; Wang, H. S.; Wang, Y. S.; Xu, Y. T.; Gao, C. X.; Cui, X. X.; Guo, Q.; Peng, B.

    2016-11-01

    Watts-level ultra-short wavelength operation of a Tm-doped all fiber laser was developed by using a 1550 nm Er-doped fiber laser pump source and a pair of fiber Bragg gratings (FBGs). The laser yielded 1.28 W of continuous-wave output at 1707.01 nm with a narrow linewidth of ~44 pm by means of a 20 cm Tm-doped fiber. The dependencies of the slope efficiencies and pump threshold of the Tm-doped fiber laser versus the length of active fiber and reflectivity of the output mirror (FBG) were investigated in detail, in which the maximum average slope efficiency was 36.1%. There is no doubt that this all fiber laser will be a perfect pump source for mid-IR laser output.

  11. Application of fiber Bragg grating sensing technology in long-distance detection of temperature in weapon depots

    Science.gov (United States)

    Xu, Jianguo; Zhang, ZhiLi; Zhao, Bing; Fu, Zhulin

    2010-10-01

    Incessantly long-term real-time detection of temperature is demanded in weapon depots, where the weapon equipment is stored in, to realize the self-regulation of temperature. Long-Distance intellectualized control can be actualized by setting sensor-net which is composed by several temperature sensors to simultaneously detect multi-point and multi- parameter. The temperature sensors based on Fiber Bragg Grating Technology are more suitable for long-term detection for their preponderance in high sensitivity, small volume, anti-jamming and so on. The temperature sensing system, which is composed by several Fiber Bragg Grating sensors in one light-cable, can accomplish Quasi-Distributed measurement and is suitable for multi-point and multi- parameter detection. Basal principle of Fiber Bragg Grating sensing technology is expounded in the article, with a sensing system applied to the long-distance detection of temperature in the depots is designed based on F-P Scanning Method. Besides, DSP and FPGA are adopted pre-treat the transformed data from AD such as filter and determine threshold. The main modules of this demodulation system such as 1550nm exact photoelectric detection module and trigonal wave voltage scan module are designed in this paper to realize demodulation. Proved by the analysis of the testing data, the Fiber Bragg Grating temperature sensing system, whose testing precision achieved the design purpose, has advantages of real-time measure and long-term stability. The system, which provides guarantee to realize the auto-control of temperature, can be generalized and will provide favorable foundation for the broad using of Fiber Bragg Grating sensing technology in the army.

  12. Pulse transit time differential measurement by fiber Bragg grating pulse recorder.

    Science.gov (United States)

    Umesh, Sharath; Padma, Srivani; Ambastha, Shikha; Kalegowda, Anand; Asokan, Sundarrajan

    2015-05-01

    The present study reports a noninvasive technique for the measurement of the pulse transit time differential (PTTD) from the pulse pressure waveforms obtained at the carotid artery and radial artery using fiber Bragg grating pulse recorders (FBGPR). PTTD is defined as the time difference between the arrivals of a pulse pressure waveform at the carotid and radial arterial sites. The PTTD is investigated as an indicator of variation in the systolic blood pressure. The results are validated against blood pressure variation obtained from a Mindray Patient Monitor. Furthermore, the pulse wave velocity computed from the obtained PTTD is compared with the pulse wave velocity obtained from the color Doppler ultrasound system and is found to be in good agreement. The major advantage of the PTTD measurement via FBGPRs is that the data acquisition system employed can simultaneously acquire pulse pressure waveforms from both FBGPRs placed at carotid and radial arterial sites with a single time scale, which eliminates time synchronization complexity.

  13. 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.

  14. 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.

  15. Development of a low-cost and miniaturized fiber Bragg grating strain sensor system

    Science.gov (United States)

    Yuan, Lili; Zhao, Yao; Sato, Shinya

    2017-05-01

    A fiber Bragg grating (FBG) strain sensor system that measures strains from reflected power changes of FBGs is presented. A laser diode used as a light source and a power meter are used in the system, which makes the FBG sensor system inexpensive and miniaturized. The reflected power of an FBG is expressed by the product of the reflectivity of the FBG and the optical power of the laser diode. Comparison of the strain applied in the experiment with that calculated from the reflected power shows that relative errors are within 5.1%, which verifies the feasibility of the strain sensor system proposed in this work. In addition, on the basis of this method, we fabricate a cantilever load cell using an FBG as the strain gauge instead of an electrical resistance, and also quantify the load range that can be measured by this load cell.

  16. Conversion of orbital angular momentum of light in chiral fiber gratings.

    Science.gov (United States)

    Xu, Huaxing; Yang, Li

    2013-06-01

    We examine mode couplings in chiral fiber grating (CFG) with N-fold rotation symmetry in the cross section and show how the angular momentum matching condition in couplings determines the generation and conversion of orbital angular momentum (OAM) beams. Then we discuss interactions of OAM and spin angular momentum in single- and double-helix long-period CFGs excited by the fundamental core modes. Subsequently, taking right-handed elliptic-core long-period CFGs as example, we demonstrate a dual-OAM converter generating OAM beams with charge +2 and charge +4 at dual wavelengths, both with a conversion efficiency greater than 97%, as well as a broadband converter based on adiabatic coupling, with a bandwidth about 10 nm for a conversion efficiency greater than 95%.

  17. Distributed OTDR-interferometric sensing network with identical ultra-weak fiber Bragg gratings.

    Science.gov (United States)

    Wang, Chen; Shang, Ying; Liu, Xiao-Hui; Wang, Chang; Yu, Hai-Hu; Jiang, De-Sheng; Peng, Gang-Ding

    2015-11-02

    We demonstrate a distributed sensing network with 500 identical ultra-weak fiber Bragg gratings (uwFBGs) in an equal separation of 2m using balanced Michelson interferometer of the phase sensitive optical time domain reflectometry (φ-OTDR) for acoustic measurement. Phase, amplitude, frequency response and location information can be directly obtained at the same time by using the passive 3 × 3 coupler demodulation. Lab experiments on detecting sound waves in water tank are carried out. The results show that this system can well demodulate distributed acoustic signal with the pressure detection limit of 0.122Pa and achieve an acoustic phase sensitivity of around -158dB (re rad/μPa) with a relatively flat frequency response between 450Hz to 600Hz.

  18. Highly sensitive temperature sensor based on an isopropanol-filled photonic crystal fiber long period grating

    Science.gov (United States)

    Du, Chao; Wang, Qi; Zhao, Yong; Li, Jin

    2017-03-01

    A high sensitivity measurement method for temperature has been proposed and investigated based on an isopropanol-filled photonic crystal fiber long period grating (PCF-LPG). Due to the high thermo-optic coefficient (TOC) of isopropanol, the sensitivity of the proposed temperature sensor could be effectively improved by filling isopropanol in the air waveguides of PCF. It can be found that the resonant dip will be split in two dips after filling isopropanol and the two dips have different sensitivities to surrounding temperature. Because of PCF-LPG is sensitive to the refractive index (RI) of internal filled liquid, the isopropanol-filled PCF-LPG temperature sensor has a high sensitivities of 1.356 nm/°C in the range of 20-50 °C. The simplicity and the excellent performance of our proposed device make it potential for the applications of high-precision temperature measurement is required.

  19. 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.

  20. Ultrasonic sensor employing two cascaded phase-shifted fiber Bragg gratings suitable for multiplexing.

    Science.gov (United States)

    Wu, Qi; Okabe, Yoji

    2012-08-15

    An ultrasonic sensor based on two cascaded phase-shifted fiber Bragg gratings (PS-FBGs) is proposed and demonstrated. In place of an external cavity laser, a broadband amplified spontaneous emission light source is used to demonstrate multiplexing ability suitable for sensor networks. The system has a high sensitivity to ultrasonic waves generated by a PZT actuator placed 7.5 cm away from the PS-FBG, because of the steep slope in the center of the PS-FBG spectrum. A second advantage of the phase shift is to reduce the effective sensor length, leading to the achievement of broadband characteristics. A pencil lead break test was performed and all results are compared to a traditional PZT sensor.

  1. Reliable Lifetime Prediction for Passivated Fiber Bragg Gratings for Telecommunication Applications

    Directory of Open Access Journals (Sweden)

    Matthieu Lancry

    2014-03-01

    Full Text Available This paper is dedicated to the lifetime prediction of Type I Fiber Bragg gratings (FBG and to problems that happen when stabilization (also called passivation conditions or the industrial conditioning procedure depart from ageing ones (e.g., presence of hydrogen during the passivation process. For the first time, a reliable procedure to certify the predicted lifetime based on a “restricted” master curve built on real components (i.e., passivated FBG is presented. It is worth noting that both procedures (master curve built on non-passivated or on passivated components are based on the same model (demarcation energy approximation and the existence of a master curve fed with ageing data (reflectivity decay vs. time and temperature. If the Master Curve (MC build on passivated components can be derived from the original one, we can certify the lifetime prediction in a reliable manner.

  2. Proposal of Screening Method of Sleep Disordered Breathing Using Fiber Grating Vision Sensor

    Science.gov (United States)

    Aoki, Hirooki; Nakamura, Hidetoshi; Nakajima, Masato

    Every conventional respiration monitoring technique requires at least one sensor to be attached to the body of the subject during measurement, thereby imposing a sense of restraint that results in aversion against measurements that would last over consecutive days. To solve this problem, we developed a respiration monitoring system for sleepers, and it uses a fiber-grating vision sensor, which is a type of active image sensor to achieve non-contact respiration monitoring. In this paper, we verified the effectiveness of the system, and proposed screening method of the sleep disordered breathing. It was shown that our system could equivalently measure the respiration with thermistor and accelerograph. And, the respiratory condition of sleepers can be grasped by our screening method in one look, and it seems to be useful for the support of the screening of sleep disordered breathing.

  3. A novel biomimetic whisker technology based on fiber Bragg grating and its application

    Science.gov (United States)

    Zhao, Chenlu; Jiang, Qi; Li, Yibin

    2017-09-01

    The paper describes a novel, biomimetic whisker-based sensing technology following the basic design of the facial whiskers of animals such as rats and mice. The sensor consists of a 3× 2 whisker array on each side of a robot. In experiments with the artificial whiskers, the motor drives rotating whiskers, and the center wavelength of a fiber Bragg grating pasted on the whisker will shift when the whisker touches an obstacle. The distance will be obtained by processing the wavelength shift data with algorithms. Then the shape recognition can be realized by postprocessing the distance data. The experimental results prove that the whisker array is capable of accurately gathering the distance and shape information of an object.

  4. 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.

  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. Study on weigh-in-motion system based on chirped fiber gratings

    Science.gov (United States)

    Zhang, Dong-sheng; Guo, Dan; Li, Wei; Li, Yong-guo; Wu, An; Yao, Kai-fang; Jiang, De-sheng

    2007-11-01

    A novel weigh-in-motion (WIM) system used for high way is developed based on Chirped fiber Bragg gratings (CFBG) in this paper. The WIM system consists of four CFBG pressure sensors, each of which contains a couple of CFBG. The sensor can directly output optical intensity signal, so the postprocessor instrument is simple and cheap instead of expensive wavelength demodulation apparatus. Theoretical and experimental results indicate that output optical intensity of the sensor is linearly proportional to the pressure, and the linearity and the repeated error can respectively reach to 0.9997 and 0.05%FS. We have also exceeded series experiments with several kinds of automobile with different velocity, and received good results of relative error below 5%.

  7. Spectra power and bandwidth of fiber Bragg grating under influence of gradient strain

    Science.gov (United States)

    Liu, Qinpeng; Qiao, Xueguang; Jia, Zhen'an; Fu, Haiwei

    2016-12-01

    The reflective spectrum power and the bandwidth of the fiber Bragg grating (FBG) under gradient strain are researched and experimentally demonstrated. The gradient strain is applied on the FBG, which can induce FBG bandwidth broadening, resulting in the variation of reflective power. Based on the coupled-mode theory and transfer matrix method, the segmental linear relationship between the gradient strain, the reflective power, and the bandwidth is simulated and analyzed, and the influence of the FBG length on the reflective spectrum is analyzed. In the experiment, the strict gradient stain device is designed; the experimental results indicate that the reflective optic power and the bandwidth of the FBG under gradient stain are concerned with the length of the FBG. Experimental results are well consistent with the theoretical analysis, which have important guiding significance in the FBG dynamic sensing.

  8. Spectra power and bandwidth of fiber Bragg grating under influence of gradient strain

    Science.gov (United States)

    Liu, Qinpeng; Qiao, Xueguang; Jia, Zhen'an; Fu, Haiwei

    2016-09-01

    The reflective spectrum power and the bandwidth of the fiber Bragg grating (FBG) under gradient strain are researched and experimentally demonstrated. The gradient strain is applied on the FBG, which can induce FBG bandwidth broadening, resulting in the variation of reflective power. Based on the coupled-mode theory and transfer matrix method, the segmental linear relationship between the gradient strain, the reflective power, and the bandwidth is simulated and analyzed, and the influence of the FBG length on the reflective spectrum is analyzed. In the experiment, the strict gradient stain device is designed; the experimental results indicate that the reflective optic power and the bandwidth of the FBG under gradient stain are concerned with the length of the FBG. Experimental results are well consistent with the theoretical analysis, which have important guiding significance in the FBG dynamic sensing.

  9. Fiber Bragg-grating strain sensor interrogation using laser radio-frequency modulation.

    Science.gov (United States)

    Gagliardi, G; Salza, M; Ferraro, P; De Natale, P

    2005-04-04

    We demonstrate the possibility of using radio-frequency modulation spectroscopic techniques for interrogation of fiber Bragg-grating (FBG) structures. Sidebands at 2 GHz are superimposed onto the output spectrum of a 1560-nm DFB diode laser. The power reflected by an FBG is demodulated at multiples of the sideband frequency. The sideband-to-carrier beat signal is shown to be extremely sensitive to Bragg wavelength shifts due to mechanical stress. Using this method, both static and dynamic strain measurements can be performed, with a noise-equivalent sensitivity of the order of 150 nepsilon/ radicalHz, in the quasi-static domain (2 Hz), and 1.6 nepsilon/ radicalHz at higher frequencies (1 kHz). The measured frequency response is presently limited at 20 kHz only by the test device bandwidth. A long-term reproducibility in strain measurements within 100 nepsilon is estimated from laser frequency drift referred to molecular absorption lines.

  10. Ultrasonic imaging of seismic physical models using a phase-shifted fiber Bragg grating.

    Science.gov (United States)

    Guo, Jingjing; Xue, Shigui; Zhao, Qun; Yang, Changxi

    2014-08-11

    We report what is to our knowledge the first ultrasonic imaging of seismic physical models by using a phase-shifted fiber Bragg grating (PS-FBG). Seismic models, which consist of multiple layer structures, were immersed in water. Piezoelectric (PZT) transducer was used to generate ultrasonic waves and a PS-FBG as a receiver. Two-dimensional (2D) ultrasonic images were reconstructed by scanning the PS-FBG with a high-precision position scanning device. In order to suppress the low-frequency drift of the Bragg wavelength during scanning, a tight wavelength tracking method was employed to lock the laser to the PS-FBG resonance in its reflection bandgap. The ultrasonic images captured by the PS-FBG have been compared with the images obtained by the geophysical imaging system, Sinopec, demonstrating the feasibility of our PS-FBG based imaging system in seismic modeling studies.

  11. Research on the gear operating state detection based on the fiber Bragg grating sensing technology

    Science.gov (United States)

    Liu, Yijun; Zhang, Wenying; Jin, Zhouyi; Liu, Jiapei; Li, Mingyue; Li, Xin; Geng, Biao; Dong, Bo

    2017-09-01

    With the development of people’s production and the accelerated growth of industrial demand, industrial manufacturers continue to improve the level of real-time detection of gear requirements. In order to improve the safety of mechanical equipment and to reduce the gear failure of the economic losses, the real-time monitoring of gear running technology is of a positive meaning. Based on the existing research results of gear dynamic detection, this paper proposes a fiber-optic grating sense of the gear operating state detection system. Stress tests were performed by varying the different load torques. The experimental results show that at the load of 10Nm and the rotating speed of 70r/min, the dedendum stress reached 130.4MPa. Compared with the theoretical value, the test error was 6.66%.

  12. Cladding mode coupling in highly localized fiber Bragg gratings: modal properties and transmission spectra

    CERN Document Server

    Thomas, Jens; Becker, Ria G; Marshall, Graham D; Withford, Michael J; Tünnermann, Andreas; Nolte, Stefan; Steel, M J

    2010-01-01

    The spectral characteristics of a fiber Bragg grating (FBG) with a transversely inhomogeneous refractive index profile, differs con- siderably from that of a transversely uniform one. Transmission spectra of inhomogeneous and asymmetric FBGs that have been inscribed with focused ultrashort pulses with the so-called point-by-point technique are investigated. The cladding mode resonances of such FBGs can span a full octave in the spectrum and are very pronounced (deeper than 20dB). Using a coupled-mode approach, we compute the strength of resonant coupling and find that coupling into cladding modes of higher azimuthal order is very sensitive to the position of the modification in the core. Exploiting these properties allows precise control of such reflections and may lead to many new sensing applications.

  13. A Fiber Bragg Grating Pressure Sensor and Its Application to Pipeline Leakage Detection

    Directory of Open Access Journals (Sweden)

    Jun Huang

    2013-01-01

    Full Text Available The fiber Bragg grating (FBG technology has been rapidly applied in the sensing technology field. In this paper, an FBG pressure sensor is designed and implemented to detect the leakage of prestressed concrete cylinder pipe (PCCP. The pressure sensor is mainly based on a Bourdon tube with two FBGs bonded on its outside and inside surfaces, respectively. The measurement principle and simulation analysis results are described. The wavelength shift difference of the two FBGs is utilized as a pressure sensing signal, the sensitivity is enhanced, and the temperature cross-sensitivity is compensated. Experimental results indicate that the measurement sensitivity is 1.414 pm/kPa in a range from 0 to 1 MPa, and the correlative coefficient reaches 99.949%. This kind of pressure sensor is effective to quasi-distributed measure and online monitor pressure of gas or liquid in industry and manufacture fields.

  14. Real-time monitoring of railway traffic using fiber Bragg gratings

    Science.gov (United States)

    Filograno, M. L.; Rodriguez-Barrios, A.; Corredera, P.; Martin-Lopez, S.; Rodriguez-Plaza, M.; Andres-Alguacil, A.; Gonzalez-Herraez, M.

    2010-09-01

    In this work we present field tests concerning the application of Fiber Bragg Grating (FBG) sensors for the monitoring of railway traffic. The test campaigns are performed on the Spanish high speed line Madrid-Barcelona, with different types of trains (S-102 TALGO-BOMBARDIER, S-103 SIEMENS-VELARO and S-120 CAF). We located the FBG sensors in the rail track at 70 km from Madrid in the country side, where the trains primarily are tested during commercial operation with maximum speeds between 250-300 km/h. The FBG sensor interrogation system used allows the simultaneous monitoring of four FBG sensors at 8000 samples/s. The different position of the FBG sensors in relation with the rail can be used with different purposes such as train identification, axle counting, speed and acceleration detection, wheel imperfections monitoring and dynamic load calculation.

  15. NOVEL FIBER GRATING SENSOR DEMODULATION TECHNIQUE BASED ON OPTICAL WAVELET FILTERING

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The optical wavelet filter is designed. It can filter and choose frequency swiftly. It can realize demodulation of distributed fiber Bragg grating(FBG) measurement system. Its scanning resolution and scanning period depend on wavelet function. Wavelet function is controlled by computer. Compared to conventional scan filter, optical wavelet filtering has some advantages such as simple structure, high scan frequency, high resolution and good linearity. At last, the error of optical wavelet filter scanning procedure is analyzed. Scanning step length refers to the shifting of optical wavelet window's central frequency. It affects system precision directly. If scanning step length is different, the measured signal is different. The methods of reducing step length guarantee scanning periodic time are presented.

  16. 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.

  17. Polarization-resolved evanescent wave scattering from gold-coated tilted fiber gratings.

    Science.gov (United States)

    Shen, Changyu; Zhou, Wenjun; Albert, Jacques

    2014-03-10

    The scatterings of TE- and TM-polarized evanescent wave on the surface of a tilted fiber Bragg grating (TFBG) with a 50 nm thick gold coating were investigated experimentally by observing radiation patterns from discontinuities in the coating. The scattering intensity for TM-polarized light is larger than for TE light when the evanescent wave propagates from the coating towards the discontinuity. The opposite occurs for light propagating from an uncoated section towards the coating edge. However in the latter case the scattering is much weaker. These results confirm that cladding modes with TE and TM polarization can be excited selectively with a TFBG, and that they scatter light differentially at discontinuities. These results are used to propose a simple polarimeter design based on total scattered light intensity monitoring.

  18. Thermal tuning of volume Bragg gratings for spectral beam combining of high-power fiber lasers.

    Science.gov (United States)

    Drachenberg, Derrek R; Andrusyak, Oleksiy; Venus, George; Smirnov, Vadim; Glebov, Leonid B

    2014-02-20

    High-radiance lasers are desired for many applications in defense and manufacturing. Spectral beam combining (SBC) by volume Bragg gratings (VBGs) is a very promising method for high-radiance lasers that need to achieve 100 kW level power. Laser-induced heating of VBGs under high-power radiation presents a challenge for maintaining Bragg resonance at various power levels without mechanical realignment. A novel thermal tuning technique and apparatus is presented that enables maintaining peak efficiency operation of the SBC system at various power levels without any mechanical adjustment. The method is demonstrated by combining two high-power ytterbium fiber lasers with high efficiency from low power to full combined power of 300 W (1.5 kW effective power), while maintaining peak combining efficiency within 0.5%.

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

    CERN Document Server

    AUTHOR|(CDS)2071648; Bianco, S; 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.

  20. Fiber Bragg Grating Measuring System for Simultaneous Monitoring of Temperature and Humidity in Mechanical Ventilation

    Directory of Open Access Journals (Sweden)

    Carlo Massaroni

    2017-04-01

    Full Text Available During mechanical ventilation, the humidification of the dry air delivered by the mechanical ventilator is recommended. Among several solutions, heated wire humidifiers (HWHs have gained large acceptance to be used in this field. The aim of this work is to fabricate a measuring system based on fiber Bragg grating (FBG for the simultaneous monitoring of gas relative humidity (RH and temperature, intended to be used for providing feedback to the HWHs’ control. This solution can be implemented using an array of two FBGs having a different center wavelength. Regarding RH monitoring, three sensors have been fabricated by coating an FBG with two different moisture-sensitive and biocompatible materials: the first two sensors were fabricated by coating the grating with a 3 mm × 3 mm layer of agar and agarose; to investigate the influence of the coating thickness to the sensor response, a third sensor was developed with a 5 mm × 5 mm layer of agar. The sensors have been assessed in a wide range of RH (up to 95% during both an ascending and a subsequent descending phase. Only the response of the 3 mm × 3 mm-coated sensors were fast enough to follow the RH changes, showing a mean sensitivity of about 0.14 nm/% (agar-coated and 0.12 nm/% (agarose-coated. The hysteresis error was about <10% in the two sensors. The contribution of temperature changes on these RH sensors was negligible. The temperature measurement was performed by a commercial FBG insensitive to RH changes. The small size of these FBG-based sensors, the use of biocompatible polymers, and the possibility to measure both temperature and RH by using the same fiber optic embedding an array of two FBGs make intriguing the use of this solution for application in the control of HWHs.

  1. 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.

  2. 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

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

    Directory of Open Access Journals (Sweden)

    Marco Ciocchetti

    2015-09-01

    Full Text Available 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

  4. Double resonance long period fiber grating for detection of E. coli in trace concentration by choosing a proper bacteriophage

    Science.gov (United States)

    Chiniforooshan, Y.; Celebanska, A.; Janik, M.; Mikulic, P.; Haddad, F.; Perreault, J.; Bock, W. J.

    2017-04-01

    There is a critical need of a fast, specific and reliable assay for biological species. To address this need, long period fiber gratings (LPFG) among other fiber optic sensors can be used because of their high sensitivity to changes in surrounding medium. In this work we fabricated and used two over-etched LPFGs. One of them was covered with T4 Phage and the other was covered with MS2 phage that both specifically bind with Escherichia coli (E. coli) bacteria. This bacterium is a major cause of the food contaminations and outbreaks. We showed achieving a highest sensitivity region of the LPFG and the way to fine tune to that region by over-etching the grating. Finally, using the highly sensitive LPFG platform we could detect E. coli at concentrations as low as 100 colony forming units (CFU), by covering the LPFG with an optimized bio-functionalization of the fiber surface with MS2 bacteriophage.

  5. Novelty design in gain flattening filter of ASE source based on fat ultra-long period fiber grating

    Science.gov (United States)

    Nafchi, Fereshteh Mohammadi; Shahi, Sharifeh; Shaffaatifar, Mohammad Taha; Kanani, Mohammad; Noormohammadi, Hossein

    2016-09-01

    A new type of gain flattening filter for amplified spontaneous emission (ASE) source based on erbium doped fiber (EDF) is proposed and demonstrated by fabricating and writing two series ultra-long period fiber grating (ULPFG) on single mode fiber (SMF-28). The novelty method in this research is based on writing the two ULPFGs as fat gratings. The LPG is written by a simple and available arc-discharge method. The pump power based on single-pass backward pump configuration is around 100 mW, and the average wavelength is near to 974 nm. The gain flattening profile is obtained by 3.4 (±1.7) dB ripple in the wavelength range between 1524 nm and 1565 nm with 41-nm band width.

  6. Glass fiber-reinforced polymer packaged fiber Bragg grating sensors for low-speed weigh-in-motion measurements

    Science.gov (United States)

    Al-Tarawneh, Mu'ath; Huang, Ying

    2016-08-01

    The weight of rolling trucks on roads is one of the critical factors for the management of road networks due to the continuous increase in truck weight. Weigh-in-motion (WIM) sensors have been widely used for weight enforcement. A three-dimensional glass fiber-reinforced polymer packaged fiber Bragg grating sensor (3-D GFRP-FBG) is introduced for in-pavement WIM measurement at low vehicle passing speed. A sensitivity study shows that the developed sensor is very sensitive to the sensor installation depth and the longitudinal and transverse locations of the wheel loading position. The developed 3-D GFRP-FBG sensor is applicable for most practical pavements with a panel length larger than 6 ft, and it also shows a very good long-term durability. For the three components in 3-D of the developed sensor, the longitudinal component has the highest sensitivity for WIM measurements, followed by the transverse and vertical components. Field testing validated the sensitivity and repeatability of the developed 3-D GFRP-FBG sensor. The developed sensor provides the transportation agency one alternative solution for WIM measurement, which could significantly improve the measurement efficiency and long-term durability.

  7. Theoretical analysis of transmission characteristics for all fiber, multi-cavity Fabry-Perot filters based on fiber Bragg gratings

    Institute of Scientific and Technical Information of China (English)

    XU OU; LU ShaoHua; DONG XiaoWei; LI Bin; NING TiGang; JIAN ShuiSheng

    2008-01-01

    The characteristics of transmission spectra for the all fiber, multi-cavity FabryPerot (FP) configuration based on fiber Bragg gratings (FBG) are theoretically analyzed and modeled. The general transmission matrix function for the structure with any number of cavities is derived, and explicit expression of the power trans-mission coefficient for symmetrical two-cavity FP is presented. The general condi-tions for flat-top single resonant peak at the central wavelength in FBG stop band are derived and verified in the numerical simulation section. The transmission peaks of single-cavity and two-cavity FP structures are compared and discussed, and results show that compared to the single-cavity FP, flatness of the top and steepness at the edge of transmission peak can be improved by introducing one more cavity. The resonant transmission peak properties of two-cavity structure are investigated in detail for various values of cavity length and FBGs with different reflection characteristics, and the design guidelines for transmission-type filters are presented. The results show that the steepness of peak slope can be improved by increase of FBG reflectivities, and these kinds of filters can be used as nar-row-band single-channel selectors and multi-channel wavelength de-multiplexing by properly choosing the length of cavities and reflectivities of FBGs.

  8. A narrow-line Erbium-doped fiber laser and its application for testing fiber Bragg gratings

    Science.gov (United States)

    Guzmán-Chávez, A. D.; Barmenkov, Yu. O.; Kir'yanov, A. V.; Mendoza-Santoyo, F.

    2009-09-01

    We inspect the spectral features of a diode-pumped Erbium-doped fiber laser (EDFL) with a Fabry-Perot cavity composed of a wavelength-selective coupler in the form of fiber Bragg grating (FBG) and wavelength-insensitive Faraday rotator mirror (FRM). High accuracy for the spectral measurements is provided with the use of an optical heterodyne scheme where the EDFL output is mixed with radiation from a narrow-line semiconductor laser, allowing the detection of the EDFL spectra with a sub-pm resolution. The heterodyne scheme permits precise measurements of the EDFL line-width as a function of the cavity length and pump power. It is worth noticing a narrow-line (a few pm) operation of the EDFL with a short length (pump power over the laser threshold. The spectral response of the EDFL to a slow sinusoidal modulation of a physical length of the FBG coupler is analyzed and it is shown that as high as ˜1-nm modulation of the EDFL optical spectrum is attainable at maximal modulation amplitudes. The narrow-line EDFL with a modulated generation wavelength is hereby demonstrated to be a tool for high-resolution measurements of reflection spectra of FBGs, which is to the best of our knowledge a novel application of the EDFL.

  9. Investigation of Structural Properties of Carbon-Epoxy Composites Using Embedded Fiber-Optic Bragg Gratings

    Science.gov (United States)

    Osei, Albert J.

    2003-01-01

    Real time monitoring of the mechanical integrity and stresses on key aerospace composite structures like aircraft wings, walls of pressure vessels and fuel tanks or any other structurally extended components and panels as in space telescopes is very important to NASA. Future military and commercial aircraft as well as NASA space systems such as Space Based Radar and International Space Station will incorporate a monitoring system to sense any degradation to the structure. In the extreme flight conditions of an aerospace vehicle it might be desirable to measure the strain every ten centimeters and thus fully map out the strain field of a composite component. A series of missions and vehicle health management requirements call for these measurements. At the moment thousands of people support a few vehicle launches per year. This number can be significantly reduced by implementing intelligent vehicles with integral nervous systems (smart structures). This would require maintenance to be performed only as needed. Military and commercial aircrafts have an equally compelling case. Annual maintenance costs are currently reaching astronomical heights. Monitoring techniques are therefore required that allow for maintenance to be performed only when needed. This would allow improved safety by insuring that necessary tasks are performed while reducing costs by eliminating procedures that are costly and not needed. The advantages fiber optical sensors have over conventional electro-mechanical systems like strain gauges have been widely extolled in the research literature. These advantages include their small size, low weight, immunity to electrical resistance, corrosion resistance, compatibility with composite materials and process conditions, and multiplexing capabilities. One fiber optic device which is suitable for distributed sensing is the fiber Bragg grating (FBG). This is a periodic perturbation in the refractive index of the fiber core. When a broadband light is

  10. Sensing and Demodulation of Special Long-Period Fiber Gratings Induced by Scanning CO2 Laser Pulses

    Directory of Open Access Journals (Sweden)

    Tao Zhu

    2012-01-01

    Full Text Available A review of long-period fiber gratings (LPFGs with special structures induced by scanning CO2 laser pulses in single mode fiber (SMF is presented in this paper. In the first part, the special structures and fabrication methods of LPFGs are demonstrated in detail. Next, the special LPFG-based sensors are demonstrated, such as refractive index sensor, strain sensor with temperature compensation, and torsion sensor without temperature crosstalking. Finally, several investigation methods including intensity, wavelength shift, and fiber ring laser demodulation are discussed.

  11. Creation of a microstructured polymer optical fiber with UV Bragg grating inscription for the detection of extensions at temperatures up to 125°C

    DEFF Research Database (Denmark)

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

    2016-01-01

    We describe the fabrication of a polycarbonate (PC) micro-structured polymer optical fiber (mPOF) and the writing offiber Bragg gratings (FBGs) in it to enable strain and temperature measurements. We demonstrate the photosensitivity ofa dopant-free PC fiber by grating inscription using a UV laser....... We further show that PC Bragg gratings can be extendedup to at least 3% without affecting the initial functionality of the micro-structured fiber. The response of PC FBGs totemperature up to 125°C is also investigated. Polycarbonate has good mechanical properties and its high...

  12. Long period gratings and rocking filters written with a CO 2 laser in highly-birefringent boron-doped photonic crystal fibers for sensing applications

    Science.gov (United States)

    Carvalho, J. P.; Anuszkiewicz, A.; Statkiewicz-Barabach, G.; Baptista, J. M.; Frazão, O.; Mergo, P.; Santos, J. L.; Urbanczyk, W.

    2012-02-01

    In this work, we demonstrate the possibility of fabricating short-length long-period gratings and rocking filters in highly birefringent Photonic Crystal Fiber using a CO 2 laser. In our experiments both kinds of gratings were made in the same Boron doped highly birefringent PCF using similar exposure parameters. We also present the sensing capabilities of both fabricated gratings to temperature, strain and hydrostatic pressure by interrogation of the wavelength shifts at different resonances.

  13. CO2 sensing at room temperature using carbon nanotubes coated core fiber Bragg grating

    Science.gov (United States)

    Shivananju, B. N.; Yamdagni, S.; Fazuldeen, R.; Sarin Kumar, A. K.; Hegde, G. M.; Varma, M. M.; Asokan, S.

    2013-06-01

    The sensing of carbon dioxide (CO2) at room temperature, which has potential applications in environmental monitoring, healthcare, mining, biotechnology, food industry, etc., is a challenge for the scientific community due to the relative inertness of CO2. Here, we propose a novel gas sensor based on clad-etched Fiber Bragg Grating (FBG) with polyallylamine-amino-carbon nanotube coated on the surface of the core for detecting the concentrations of CO2 gas at room temperature, in ppm levels over a wide range (1000 ppm-4000 ppm). The limit of detection observed in polyallylamine-amino-carbon nanotube coated core-FBG has been found to be about 75 ppm. In this approach, when CO2 gas molecules interact with the polyallylamine-amino-carbon nanotube coated FBG, the effective refractive index of the fiber core changes, resulting in a shift in Bragg wavelength. The experimental data show a linear response of Bragg wavelength shift for increase in concentration of CO2 gas. Besides being reproducible and repeatable, the technique is fast, compact, and highly sensitive.

  14. Process monitoring of glass reinforced polypropylene laminates using fiber Bragg gratings

    KAUST Repository

    Mulle, Matthieu

    2015-12-29

    Hot-press molding of glass-fiber-reinforced polypropylene (GFPP) laminates was monitored using longitudinally and transversely embedded fiber Bragg gratings (FBGs) at different locations in unidirectional laminates. The optical sensors proved to efficiently characterize some material properties; for example, strain variations could be related physical change of the laminate, revealing key transition points such as the onset of melt or solidification. These results were confirmed through some comparison with traditional techniques such as differential scanning calorimetry. After the GFPP plate was released from the mold, residual strains were estimated. Because cooling rate is an important process parameter in thermoplastics, affecting crystallinity and ultimately residual strain, two different conditions (22 and 3 °C/min) were investigated. In the longitudinal direction, results were nearly identical while in the transverse direction results showed a 20% discrepancy. Coefficients of thermal expansion (CTE) were also identified during a post-process heating procedure using the embedded FBGs and compared to the results of a thermo-mechanical analysis. Again, dissimilarities were observed for the transverse direction. With regards to through the thickness properties, no differences were observed for residual strains or for CTEs.

  15. A practical distributed Fiber Bragg grating temperature sensor system based on STM32 processor platform

    Science.gov (United States)

    Liu, Jinjun; Cheng, Yongxin; Wang, Guangyu; Zhang, Yanjun

    2015-10-01

    A practical distributed FBG temperature sensor system based on STM32 processor platform is presented in this paper and this FBG sensing system can realize single-channel and multi-point temperature measurement. Because the measured area has been divided into several parts, every part has several fiber Bragg gratings with the same wavelength. There is no need to get the temperature of each point, just get the temperature field information of the parts. In other words, if the temperature of points is varied, the largest varied temperature of the points in one part can be obtained as the temperature of this part. So in the system only use one light source, but more FBGs can be implanted in a fiber, which can effectively reduce costs and complexity. In signal processing system, the FFP-TF control circuit cans precise control without distortion of FFP-TF; high precision photoelectric detection circuit can achieve nW level optical power detection; wavelength demodulation algorithm can achieve system synchronization. The PC monitoring software based on VC++ is used to display the monitoring interface. The experiment results indicated that temperature precision is 1°C and the linearity is over 99.6%. All experiments can be reproducible. It has been seen in experiments that the system has the characteristics of the high measured stable, good reliability, low cost and can meet the needs of the engineering measurements.

  16. CO2 sensing at room temperature using carbon nanotubes coated core fiber Bragg grating.

    Science.gov (United States)

    Shivananju, B N; Yamdagni, S; Fazuldeen, R; Sarin Kumar, A K; Hegde, G M; Varma, M M; Asokan, S

    2013-06-01

    The sensing of carbon dioxide (CO2) at room temperature, which has potential applications in environmental monitoring, healthcare, mining, biotechnology, food industry, etc., is a challenge for the scientific community due to the relative inertness of CO2. Here, we propose a novel gas sensor based on clad-etched Fiber Bragg Grating (FBG) with polyallylamine-amino-carbon nanotube coated on the surface of the core for detecting the concentrations of CO2 gas at room temperature, in ppm levels over a wide range (1000 ppm-4000 ppm). The limit of detection observed in polyallylamine-amino-carbon nanotube coated core-FBG has been found to be about 75 ppm. In this approach, when CO2 gas molecules interact with the polyallylamine-amino-carbon nanotube coated FBG, the effective refractive index of the fiber core changes, resulting in a shift in Bragg wavelength. The experimental data show a linear response of Bragg wavelength shift for increase in concentration of CO2 gas. Besides being reproducible and repeatable, the technique is fast, compact, and highly sensitive.

  17. Grapefruit photonic crystal fiber long period gratings sensor for DNT sensing application

    Science.gov (United States)

    Tao, Chuanyi; Li, Jingke; Zhu, Tenglong

    2016-10-01

    The detection of explosives and their residues is of great importance in public health, antiterrorism and homeland security applications. The vapor pressures of most explosive compounds are extremely low and attenuation of the available vapor is often great due to diffusion in the environment, making direct vapor detection difficult. In reality bomb dogs are still the most efficient way to quickly detect explosives on the spot. Many formulations of TNT-based explosives contain DNT residues. The use of long period gratings (LPGs) formed in grapefruit photonic crystal fiber (PCF) with thin-film overlay coated on the inner surface of air holes for gas sensing is demonstrated. A gas analyteinduced index variation of the thin-film immobilized on the inner surface of the holey region of the fiber can be observed by a shift of the resonance wavelength. We demonstrate a 2,4-dinitrotoluene (DNT) sensor using grapefruit PCF-LPGs. Coating with gas-sensitive thin-film on the inner surface of the air holes of the grapefruit PCF-LPG could provide a promising platform for rapid highly sensitive gas sensing. A rapid and highly sensitive detection of DNT has been demonstrated using the grapefruit PCF-LPG sensor to show the feasibility of the proposed approach.

  18. Fabrication of deuterium-loaded fiber Bragg grating and its spectral characteristics in thermal annealing

    Science.gov (United States)

    Shih, MingChang; Wang, C. C.; Yu, Cheng-Tsang; Chuang, Tung J.

    2000-07-01

    Previous results showed that the non-reversible (hystersis loop) of Bragg wave length shifting in thermal cycling of the Fiber Bragg Grating which is a high germanium doped optical fiber and high pressure hydrogen loaded was due to the diffusion out of the H2 residue in thermal annealing. In addition, the O-H absorption peak (1.38nm) causes signal attenuation and stability problem in FBG applications. We demonstrated up to 250 degree(s) C. The spectrum characteristics of the D2 loaded FBG compared to the H2 loaded FBG is presented. In general, (Delta) (Lambda) B of the D2 loaded FBG is narrower than H2 loaded, and (Lambda) B of the D2 loaded FBG is more stable than H2 loaded in thermal annealing. A model base on the UV photo-induced index change in the BFG core with D2 and H2 loaded to explain the spectrum characteristics between D2 and H2 loaded FBG is discussed.

  19. Zinc oxide coated optical fiber long period gratings for sensing of volatile organic compounds

    Science.gov (United States)

    Coelho, L.; Viegas, D.; Santos, J. L.; Martins de Almeida, José Manuel Marques

    2016-04-01

    The detection of volatile organic compounds is accomplished with a sensing device based on a long period fiber grating (LPFG) coated with a zinc oxide (ZnO) thin layer with self-temperature compensation. The ZnO coating structure was produced onto the cladding of the fiber by thermal oxidation of a metallic Zn thin film. The morphological characterization of ZnO thin films, grown at the same time on silicon substrates, was performed using X-ray diffraction, X-ray Photoelectron Spectroscopy and Scanning Electron Microscope which shows very good agreement. LPFGs with 290 nm thick ZnO coating were fabricated and characterized for the detection of ethanol and hexane in vapor phase. For ethanol a sensitivity of 0.99 nm / g.m-3 was achieved when using the wavelength shift interrogation mode, while for hexane a much lower sensitivity of 0.003 nm / g.m-3 was measured, indicating a semi-selectivity of the sensor with a spectral resolution better than 3.2 g.m-3.

  20. Research of three-dimensional force sensor based on multiplexed fiber Bragg grating strain sensors

    Science.gov (United States)

    Xu, Hui-Chao; Wang, Su; Miao, Xin-Gang

    2017-04-01

    Most safety problems of architectural structures are caused by structural deformation, and the structures usually deform in more than one direction. So it is important and necessary to collect the safety monitoring data from all directions. Conventional fiber Bragg grating (FBG) sensors cannot fully meet the requirements of a modern safety monitoring system in practical application. Therefore, the research of a three-dimensional (3-D) force sensor that can expand the application range of fiber optic sensing technology is necessary and significant. A 3-D force sensor based on multiplexed FBG strain sensors is proposed, which can be used to measure 3-D force on a structure under test, force distribution, and the trend of relative microdeformation. The sensor that has an integral structure with a design has been described in detail, and its sensing principle has been investigated. The results of calibration experiments show that it can accurately and effectively realize the 3-D force measurement with good linearity, repeatability, and consistency. Experimental and analytical results both demonstrate its feasibility. It can work in harsh environments due to its good stability and anti-interference ability. The sensor proposed in this paper has great engineering application value and application prospects in the field of structure health monitoring.