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Sample records for optical fiber bragg

  1. 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....

  2. Cascaded Bragg scattering in fiber optics.

    Science.gov (United States)

    Xu, Y Q; Erkintalo, M; Genty, G; Murdoch, S G

    2013-01-15

    We report on a theoretical and experimental study of cascaded Bragg scattering in fiber optics. We show that the usual energy-momentum conservation of Bragg scattering can be considerably relaxed via cascade-induced phase-matching. Experimentally we demonstrate frequency translation over six- and 11-fold cascades, in excellent agreement with derived phase-matching conditions.

  3. 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.

  4. 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....

  5. New cobweb-structure hollow Bragg optical fibers

    Institute of Scientific and Technical Information of China (English)

    YU Rong-jin; ZHANG Yong-qiang; ZHANG Bing; WANG Chao-ran; WU Chang-qi

    2007-01-01

    A new type of Bragg fibers,i.e. hollow-core cobweb-structured optical fibers,which can be used to the low-loss transmission from visible to near infrared region (0.65 μm-1.55 μm),terahertz wave (200 μm-480 μm) and circular-polarization-maintaining single-mode transmission are investigated. Results show that the hollow-core cobweb-structured fibers have less loss than other hollow-core Bragg fibers. The fibers can be constituted by using the plastics or glasses with large absorption losses.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  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. 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...

  13. 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.

  14. 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....

  15. 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

  16. 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.

  17. 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

  18. 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...

  19. 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.

  20. 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...

  1. Studies of beam expansion and distributed Bragg reflector lasers for fiber optics and optical signal processing

    Science.gov (United States)

    Garmire, E. M.

    1981-03-01

    Separate studies were performed on beam expansion and on distributed Bragg Reflector (DBR) lasers preliminary to monolithic integration on GaAs substrates. These components are proposed for use in optical signal processing, for fiber optic sources and for high brightness lasers.

  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. 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....

  4. 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...

  5. 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...

  6. 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.

  7. 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.

  8. 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.

  9. 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...

  10. 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.

  11. Improved thermal and strain performance of annealed polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Stefani, Alessio; Bache, Morten;

    2011-01-01

    We report on a detailed study of the inscription and characterization of fiber Bragg gratings (FBGs) in commercial step index polymer optical fibers (POFs). Through the growth dynamics of the gratings, we identify the effect of UV-induced heating during the grating inscription. We found that FBGs...

  12. 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...

  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. 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. 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.

  16. 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.

  17. Fast Interrogation of Fiber Bragg Gratings with Electro-Optical Dual Optical Frequency Combs.

    Science.gov (United States)

    Posada-Roman, Julio E; Garcia-Souto, Jose A; Poiana, Dragos A; Acedo, Pablo

    2016-11-26

    Optical frequency combs (OFC) generated by electro-optic modulation of continuous-wave lasers provide broadband coherent sources with high power per line and independent control of line spacing and the number of lines. In addition to their application in spectroscopy, they offer flexible and optimized sources for the interrogation of other sensors based on wavelength change or wavelength filtering, such as fiber Bragg grating (FBG) sensors. In this paper, a dual-OFC FBG interrogation system based on a single laser and two optical-phase modulators is presented. This architecture allows for the configuration of multimode optical source parameters such as the number of modes and their position within the reflected spectrum of the FBG. A direct read-out is obtained by mapping the optical spectrum onto the radio-frequency spectrum output of the dual-comb. This interrogation scheme is proposed for measuring fast phenomena such as vibrations and ultrasounds. Results are presented for dual-comb operation under optimized control. The optical modes are mapped onto detectable tones that are multiples of 0.5 MHz around a center radiofrequency tone (40 MHz). Measurements of ultrasounds (40 kHz and 120 kHz) are demonstrated with this sensing system. Ultrasounds induce dynamic strain onto the fiber, which generates changes in the reflected Bragg wavelength and, hence, modulates the amplitude of the OFC modes within the reflected spectrum. The amplitude modulation of two counterphase tones is detected to obtain a differential measurement proportional to the ultrasound signal.

  18. 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.

  19. 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...

  20. 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.

  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. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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.

  9. Fast Interrogation of Fiber Bragg Gratings with Electro-Optical Dual Optical Frequency Combs

    Directory of Open Access Journals (Sweden)

    Julio E. Posada-Roman

    2016-11-01

    Full Text Available Optical frequency combs (OFC generated by electro-optic modulation of continuous-wave lasers provide broadband coherent sources with high power per line and independent control of line spacing and the number of lines. In addition to their application in spectroscopy, they offer flexible and optimized sources for the interrogation of other sensors based on wavelength change or wavelength filtering, such as fiber Bragg grating (FBG sensors. In this paper, a dual-OFC FBG interrogation system based on a single laser and two optical-phase modulators is presented. This architecture allows for the configuration of multimode optical source parameters such as the number of modes and their position within the reflected spectrum of the FBG. A direct read-out is obtained by mapping the optical spectrum onto the radio-frequency spectrum output of the dual-comb. This interrogation scheme is proposed for measuring fast phenomena such as vibrations and ultrasounds. Results are presented for dual-comb operation under optimized control. The optical modes are mapped onto detectable tones that are multiples of 0.5 MHz around a center radiofrequency tone (40 MHz. Measurements of ultrasounds (40 kHz and 120 kHz are demonstrated with this sensing system. Ultrasounds induce dynamic strain onto the fiber, which generates changes in the reflected Bragg wavelength and, hence, modulates the amplitude of the OFC modes within the reflected spectrum. The amplitude modulation of two counterphase tones is detected to obtain a differential measurement proportional to the ultrasound signal.

  10. 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

  11. Studies of beam expansion and distributed Bragg reflector lasers for fiber optics and optical signal processing. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Garmire, E.M.

    1981-03-03

    Separate studies were performed on beam expansion and on Distributed Bragg Reflector (DBR) lasers preliminary to monolithic integration on GaAs substrates. These components are proposed for use in optical signal processing, for fiber optic sources and for high-brightness lasers.

  12. 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.

  13. 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.

  14. 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....

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

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

    Directory of Open Access Journals (Sweden)

    Ji Xia

    2015-07-01

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

  1. 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.

  2. 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....

  3. Optical DPSK demodulator based on pi-phase-shifted fiber Bragg grating with an optically turnable phase shifter

    DEFF Research Database (Denmark)

    Kim, T.-Y.; Hanawa, M.; Kim, Sun-Jong

    2006-01-01

    We propose and demonstrate a novel optical differential phase-shift keying (DPSK) demodulator with an optically tunable phase shifter. The proposed DPSK demodulator is implemented by using a pi-phase-shifted fiber Bragg grating and an Yb3+-Al3+ codoped optical fiber. A 10-Gb/s DPSK signal was suc...... was successfully demodulated by the proposed demodulator, showing clearly open eye diagrams as well as bit-error-free performance. Moreover, the phase of delayed optical signal can be tuned by the phase shifter that is controlled by a pumping light at around 980nm....

  4. 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.

  5. 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...

  6. Fiber Bragg distributed chemical sensor

    NARCIS (Netherlands)

    Boersma, A.; Saalmink, M.; Lucassen, T.; Wiegersma, S.; Jansen, T.H.; Jansen, R.; Cheng, L.K.

    2011-01-01

    A distributed chemical sensor is developed by coating multiple Bragg gratings in a single glass fiber with chemical responsive coatings. The composition of the coating is tuned to the target chemicals to be measured and the optical response of the coated grating is optimized by changing the coating

  7. 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.

  8. 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.

  9. Investigations on birefringence effects in polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Hu, Xiaolian; Saez-Rodriguez, D.; Bang, Ole;

    2014-01-01

    because of the larger thermo-optic coefficient and smaller Young's modulus of polymer materials. (M)POFBGs are most often photowritten in poly(methylmethacrylate) (PMMA) materials using a continuous-wave 325 nm HeCd laser. For the first time to the best of our knowledge, we study photoinduced...... dependent loss (PDL) and differential group delay (DGD) were computed from the Jones matrix eigenanalysis using an optical vector analyser. Maximum values exceeding several dB and a few picoseconds were obtained for the PDL and DGD, respectively. The response to lateral force was finally investigated...

  10. 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...

  11. 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...

  12. 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...

  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. Influence of optical fiber location behind an apodized phase mask on Bragg grating reflection efficiencies at Bragg wavelength and its harmonics

    Science.gov (United States)

    Osuch, Tomasz; Jaroszewicz, Zbigniew

    2017-01-01

    An apodized fiber Bragg grating formation using a phase mask with variable duty cycle is numerically analyzed. In particular, an impact of position of an optical fiber behind the phase mask with Gaussian apodization profile on Bragg grating reflection efficiencies at Bragg wavelength and its harmonics is extensively studied. It is shown that reflection efficiency of each harmonic strongly depends on the optical fiber location with respect to the adjacent Talbot planes during the grating inscription. An analytical formula for calculation such periodical changes of reflection strength is proposed. It is also proved, that the smaller optical fiber diameter the higher fluctuations of reflectivity for particular harmonic occur. Results presented for such general case (i.e. phase mask with variable duty cycle with all non-zero diffraction orders) directly correspond to less complex structures, such as uniform phase masks and those with variable groove depth. They are also useful in optimization of Bragg wavelength and harmonic reflection efficiencies as well as in deep understanding of apodized FBG formation using aforementioned phase masks.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Mode characteristics of hollow core Bragg fiber

    Institute of Scientific and Technical Information of China (English)

    Minning Ji; Zhidong Shi; Qiang Guo

    2005-01-01

    Analytical expression to calculate propagation constant and mode field of the hollow core Bragg fiber is derived. Numerical results are presented. It is shown that the fundamental mode of the hollow core Bragg fiber is circularly symmetric TE01 mode with no polarization degeneracy, while the higher order mode may be HE11, TM01, or TE02 etc.. This property is different from conventional optical fiber that its fundamental mode is the linearly polarized HE11 mode and is polarization degeneracy.

  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

    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...

  5. 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.

  6. 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...

  7. 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...

  8. Hybrid optical fiber sensor system based on fiber Bragg gratings and plastic optical fibers for health monitoring of engineering structures

    Science.gov (United States)

    Kuang, K. S. C.; Maalej, M.; Quek, S. T.

    2006-03-01

    In this paper, packaged fibre Bragg grating (PFBG) sensors were fabricated by embedding them in 70mm x 10mm x 0.3mm carbon-fibre composites which were then surface-bonded to an aluminium beam and a steel I-beam to investigate their strain monitoring capability. Initially, the response of these packaged sensors under tensile loading was compared to bare FBGs and electrical strain gauges located in the vicinity. The effective calibration constant/ coefficient of the PFBG sensor was also compared with the non-packaged version. These PFBG sensors were then attached to an I-section steel beam to monitor their response under flexural loading conditions. These realistic structures provide a platform to assess the potential and reliability of the PFBG sensors when used in harsh environment. The results obtained in this study gave clear experimental evidence of the difference in performance between the coated and uncoated PFBG fabricated for the study. In another experimental set-up, bare FBG and POF vibration sensors were surface-bonded to the side-surface of a CFRPwrapped reinforced concrete beam which was then subjected to cyclic loading to assess their long-term survivability. Plain plastic optical fibre (POF) sensors were also attached to the side of the 2-meter concrete beam to monitor the progression of cracks developed during the cyclic loading. The results showed excellent long-term survivability by the FBG and POF vibration sensors and provided evidence of the potential of the plain POF sensor to detect and monitor the propagation of the crack developed during the test.

  9. Wideband digitally tunable lasers based on fiber Bragg grating external cavity array and 1×N optical switch

    Institute of Scientific and Technical Information of China (English)

    Haiwen Cai(蔡海文); Jianxin Geng(耿建新); Zuoren Dong(董作人); Gaoting Chen(陈高庭); Zujie Fang(方祖捷)

    2003-01-01

    A novel wideband digitally tunable laser based on fiber Bragg grating external cavities and 1 × N optical switch provides 5 ms fast tuning time with output power more than 1 dBm over whole C-band that is only limited by the laser emission bandwidth. Less than 50 pm wavelength drift over -10 to 55℃ temperature range make that the wavelength locker and monitor are not necessary in this tunable laser.

  10. EFFECT OF OPTICAL FIBER HYDROGEN LOADING ON THE INSCRIPTION EFFICIENCY OF CHIRPED BRAGG GRATINGS BY MEANS OF KrF EXCIMER LASER RADIATION

    Directory of Open Access Journals (Sweden)

    Sergey V. Varzhel

    2016-11-01

    Full Text Available Subject of Research.We present comparative results of the chirped Bragg gratings inscription efficiency in optical fiber of domestic production with and without low-temperature hydrogen loading. Method. Chirped fiber Bragg gratings inscription was made by the Talbot interferometer with chirped phase mask having a chirp rate of 2.3 nm/cm used for the laser beam amplitude separation. The excimer laser system Coherent COMPexPro 150T, working with the gas mixture KrF (248 nm, was used as the radiation source. In order to increase the UV photosensitivity, the optical fiber was placed in a chamber with hydrogen under a pressure of 10 MPa and kept there for 14 days at 40 °C. Main Results. The usage of the chirped phase mask in a Talbot interferometer scheme has made it possible to get a full width at half-maximum of the fiber Bragg grating reflection spectrum of 3.5 nm with induced diffraction structure length of 5 mm. By preliminary hydrogen loading of optical fiber the broad reflection spectrum fiber Bragg gratings with a reflectivity close to 100% has been inscribed. Practical Relevance. The resulting chirped fiber Bragg gratings can be used as dispersion compensators in optical fiber communications, as well as the reflective elements of distributed fiber-optic phase interferometric sensors.

  11. High Performance Acousto-Optic Arrays based on Fiber Bragg Gratings for Measuring Launch Acoustics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Intelligent Fiber Optic Systems Corporation (IFOS) proposes to prove the feasibility of innovations in acousto-optic sensor development for measurement of launch...

  12. Fiber Bragg distributed chemical sensor

    NARCIS (Netherlands)

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

    2010-01-01

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

  13. 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...

  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. 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.

  16. 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.

  17. Laser-optical fiber Bragg grating anemometer for measuring gas flows: application to measuring the electric wind.

    Science.gov (United States)

    Lamb, David W; Hooper, Adam

    2006-04-15

    A novel laser-optical fiber Bragg grating anemometer (FBGA) has been devised for measuring the speed of a moving gas in the range 0-1.5 m s(-1). As a test, the FBGA was applied to measuring the speed of the electric wind generated in the particularly harsh, high-voltage environment of a dc, negative-polarity, partial (corona) discharge in atmospheric air. The instrument proved more stable and yielded an order-of-magnitude improvement in sensitivity (deltav approximately 4 x 10(-3) ms(-1)) compared with other optical-fiber-based anemometers. On-axis wind speeds ranging from zero to 1.1 m s(-1) were measured in the vicinity of the corona discharge.

  18. Monitoring of pipeline deformations using optical fiber sensors based on Bragg lattices; Monitoracao de deformacoes em dutos utilizando sensores a fibra optica com base em redes de Bragg

    Energy Technology Data Exchange (ETDEWEB)

    Moszkowica, Viktor Nigri [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil)]. E-mail: vnigri@bol.com.br

    2002-06-01

    In the petroleum sector there is a growing need for the use of pipelines as well as for their monitoring. A way to avoid leaks that can cause great damage to the environment is by the monitoring of deformations. In case failures can not be avoided through operational procedures, the monitoring of deformations can identify the initial moment and location of the leak, allowing for quick action on the part of the cleaning and depollution teams. Also important is the monitoring of slopes and soil movements. The same thing applies to production and transfer submarine pipelines subject to complex dynamic loadings that combine internal and external pressure, torsion, axial stress and, the most common of all, flexion loading. For this type of application, optical fiber sensors present a number of interesting features. Multiplexing, remote operation and long distance distribution of sensors are characteristics that attract their use in deformation monitoring systems. Presented herein are the research results of works that had the objective of developing deformation monitoring techniques in pipelines using optical fiber sensors based on Bragg grating. The technical feasibility of this technology is demonstrated through laboratorial tests. Also discussed herein are methods for field implementation of sensors, optical signal multiplexing techniques and potential advantages of applying this technology. (author)

  19. 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...

  20. 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.

  1. 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.

  2. 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)

  3. Development of optical fiber Bragg grating force-reflection sensor system of medical application for safe minimally invasive robotic surgery

    Science.gov (United States)

    Song, Hoseok; Kim, Kiyoung; Lee, Jungju

    2011-07-01

    Force feedback plays a very important role in medical surgery. In minimally invasive surgery (MIS), however, the very long and stiff bars of surgical instruments greatly diminish force feedback for the surgeon. In the case of minimally invasive robotic surgery (MIRS), force feedback is totally eliminated. Previous researchers have reported that the absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peak force magnitude by at least a factor of two. Therefore, it is very important to provide force information in MIRS. Recently, many sensors are being developed for MIS and MIRS, but some obstacles to their application in actual medical surgery must be surmounted. The most critical problems are size limit and sterilizability. Optical fiber sensors are among the most suitable sensors for the surgical environment. The optical fiber Bragg grating (FBG) sensor, in particular, offers an important additional advantage over other optical fiber sensors in that it is not influenced by the intensity of the light source. In this paper, we present the initial results of a study on the application of a FBG sensor to measure reflected forces in MIRS environments and suggest the possibility of successful application to MIRS systems.

  4. System and method for determination of the reflection wavelength of multiple low-reflectivity bragg gratings in a sensing optical fiber

    Science.gov (United States)

    Moore, Jason P. (Inventor)

    2009-01-01

    A system and method for determining a reflection wavelength of multiple Bragg gratings in a sensing optical fiber comprise: (1) a source laser; (2) an optical detector configured to detect a reflected signal from the sensing optical fiber; (3) a plurality of frequency generators configured to generate a signal having a frequency corresponding to an interferometer frequency of a different one of the plurality of Bragg gratings; (4) a plurality of demodulation elements, each demodulation element configured to combine the signal produced by a different one of the plurality of frequency generators with the detected signal from the sensing optical fiber; (5) a plurality of peak detectors, each peak detector configured to detect a peak of the combined signal from a different one of the demodulation elements; and (6) a laser wavenumber detection element configured to determine a wavenumber of the laser when any of the peak detectors detects a peak.

  5. Fault diagnosis of the rolling bearing with optical fiber Bragg grating vibration sensor

    Science.gov (United States)

    Wei, Peng; Dai, Zejing; Zheng, Leilei; Li, Ming

    2016-10-01

    Fault diagnosis of the rolling bearing means a lot for property and life safety. In this paper the Fiber Bragg Grating (FBG) vibration sensor and resonance demodulation technology are used in the fault diagnosis of the rolling bearing. Traditionally, the vibration signals are measured by the resistance strain gauge, accelerometer, etc. But those traditional electronic sensors are usually influenced by the industry electromagnetic noise. But the FBG vibration sensor is totally different. It has a lot of advantages such as small volume, light weight, easy connection and so on. And the high industry electromagnetic noise means nothing to the FBG sensors. In this paper, we use the FBG vibration and temperature sensors to measure the fast strain and temperature signal of the rolling bearing. In order to extract the fault signals from strong background noise, the resonant demodulation technology is used to analyze and process the vibration signals collected by the FBG sensors. In order to verify the reliability of the FBG vibration sensor and resonance demodulation technology applied in the fault diagnosis of the rolling bearing, several experiments are done. Five FBG vibration sensors are attached on the different parts of the rolling bearing to verify its function and its influence on the fault diagnosis of the rolling bearing. The results of the experiments show that the FBG vibration sensor method could be used in fault diagnosis of the rolling bearing. The repetitive experiments show the reliability of the FBG vibration sensors method.

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

    Science.gov (United States)

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

    2015-11-01

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

  7. Fiber Bragg Grating Based Thermometry

    CERN Document Server

    Ahmed, Zeeshan; Guthrie, William; Quintavalle, John

    2016-01-01

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

  8. 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...

  9. 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.

  10. 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.

  11. 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.

  12. Analysis of Performance Limitations in Fiber Bragg Grating Based Optical Add-Drop Multiplexer due to Crosstalk

    Directory of Open Access Journals (Sweden)

    Md. Mahiuddin

    2012-03-01

    Full Text Available Abstract— Wavelength  division  multiplexing  (WDM optical networks  are  attracting  more  and  more attention because of their ability to provide  increased capacity and  flexibility. Optical add-drop multiplexer (OADM  becomes  a  key  component  to  add  or  drop wavelengths  in  high  bit  rate  optical  networks. Crosstalk  in OADM  often degrades  the performance of WDM  system  drastically.  In  this  article,  we  have developed  analytical model  for  low  crosstalk  of  fiber Bragg  grating  based  OADM  with  isolator. We  have also  derived  analytical  expressions  for  relative intensity noise (RIN, bit error rate (BER and power penalty to evaluate the performance limitations of this OADM. Results show that crosstalk, RIN and BER of the  proposed  OADM  are significantly  lower  and provide better performance than the existing OADMs.

  13. Non-invasive timing of gas gun-launched projectiles using external surface-mounted optical fiber-Bragg grating strain gauges.

    Science.gov (United States)

    Goodwin, Peter M; Marshall, Bruce R; Stevens, Gerald D; Dattelbaum, Dana M

    2013-03-01

    Non-invasive detection methods for tracking gun-launched projectiles are important not only for assessment of gun performance but are also essential for timing a variety of diagnostics, for example, to investigate plate-impact events for shock compression experiments. Measurement of the time of passage of a projectile moving inside of the gun barrel can be achieved by detection of the transient hoop strain induced in the barrel of a light-gas gun by the passage of the projectile using external, barrel surface-mounted optical fiber-Bragg grating strain gauges. Optical fiber-Bragg gratings have been implemented and their response characterized on single-stage and two-stage light gas guns routinely used for dynamic experimentation at Los Alamos National Laboratory. Two approaches, using either broadband or narrowband illumination, were used to monitor changes in the Bragg wavelength of the fiber-Bragg gratings. The second approach, using narrowband laser illumination, offered the highest sensitivity. The feasibility of using these techniques to generate early, pre-event signals useful for triggering high-latency diagnostics was demonstrated.

  14. Dynamic behavior monitoring and damage evaluation for arch bridge suspender using GFRP optical fiber Bragg grating sensors

    Science.gov (United States)

    Li, Dongsheng; Zhou, Zhi; Ou, Jinping

    2012-06-01

    Suspenders, as the main bearing components in an arch bridge, can only manage to serve for about tens of years, or even a few years due to the influences of corrosion and fatigue load. This paper proposes a method of testing the suspender dynamic behavior with optical fiber Bragg grating sensors embedded in the glass fiber reinforced polymer (GFRP-OFBGS). Firstly, layout method of FRP-OFBGS among the suspender and protection technology are studied, and the self-monitoring smart suspender is developed. Secondly, stretching experiments were carried out on the smart suspender. The test experimental results demonstrated that the whole procedure of the stretching test can be perfectly monitored. Finally, the self-monitoring smart suspender successfully was applied in Ebian Bridge to monitor the strain history of suspenders under traffic load, and traffic effect to suspenders with various lengths and to different steel strands of a single suspender. Based on the monitoring data, the arch bridge suspenders fatigue damage dynamic evaluation methods and calculation results were given. The field monitoring results demonstrated that, the self-monitoring smart suspender mentioned in this paper is capable of monitoring suspender dynamic response and possible fatigue damages.

  15. 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.

  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. 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. Simultaneous ultrafast optical pulse train bursts generation and shaping based on Fourier series developments using superimposed fiber Bragg gratings.

    Science.gov (United States)

    García-Muñoz, Víctor; Preciado, Miguel A; Muriel, Miguel A

    2007-08-20

    We propose an all-fiber method for the generation of ultrafast shaped pulse train bursts from a single pulse based on Fourier Series Developments (FDSs). The implementation of the FSD based filter only requires the use of a very simple non apodized Superimposed Fiber Bragg Grating (S-FBG) for the generation of the Shaped Output Pulse Train Burst (SOPTB). In this approach, the shape, the period and the temporal length of the generated SOPTB have no dependency on the input pulse rate.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    , such as casting of pol-ymer granulates into a solid rod, machining and drilling of a 3-ring hexagonal lattice of holes into it, and finally drawing into fiber. We demonstrate that the obtained PC mPOF is photosensitive and FBGs can be conveniently inscribed into it, thereby enabling FBG-based temperature...

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

    Directory of Open Access Journals (Sweden)

    John Canning

    2009-01-01

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

  1. Add-Drop Demultiplexer Operating in an Optical Michelson Interferometer Based in Fiber Bragg Gratings for Time Division Multiple Access Systems

    Science.gov (United States)

    Filho, A. F. G. F.; De Sousa, J. R. R.; Guimarães, G. F.; Rocha, H. H. B.; Ferreira, A. C.; Lima, F. T.; Sombra, A. S. B.

    2010-07-01

    This article presents a numerical investigation of the propagation and switching of ultra-short pulses (∼2 ps) using a fiber-optic Michelson interferometer. In this study, the performance of the Michelson interferometer is studied as a function of the non-linear characteristics of the coupler and the fiber Bragg gratings. The numerical studies were done starting from the coupled-mode equations solved using the fourth-order Runge-Kutta method. The switching characteristic of the short pulses was examined as a function of pump power and the dephasing in the reflection amplitude of one of the Bragg gratings in order to obtain an add-drop filter operation. Transmission characteristics, such as cross-talk level, extinction ratio coefficient, and compression factor, were analyzed for different dephasing values and pump powers. Pump powers were examined from below the critical power of the coupler of switching (P = 1 W), at the critical power of switching (Pc = 1.73 W), and above (P = 1.95 W). Through this study, one can verify that the transmission, cross-talk level, extinction coefficient, and compression factor depend on the pump power inserted into the device and in the dephasing. The optical fiber Michelson interferometers with identical gratings in the two output arms implement important components as a demultiplexer in add-drop devices. This device has attracted great interest in the field of all-optical switching in telecommunications for operating with high transmission rates.

  2. 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...

  3. 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

  4. High-speed 100 MHz strain monitor using fiber Bragg grating and optical filter for magnetostriction measurements under ultrahigh magnetic fields

    Science.gov (United States)

    Ikeda, Akihiko; Nomura, Toshihiro; Matsuda, Yasuhiro H.; Tani, Shuntaro; Kobayashi, Yohei; Watanabe, Hiroshi; Sato, Keisuke

    2017-08-01

    A high-speed 100 MHz strain monitor using a fiber Bragg grating, an optical filter, and a mode-locked optical fiber laser has been devised, whose resolution is Δ L /L ˜1 0-4. The strain monitor is sufficiently fast and robust for the magnetostriction measurements of materials under ultrahigh magnetic fields generated with destructive pulse magnets, where the sweep rate of the magnetic field is in the range of 10-100 T/μ s. As a working example, the magnetostriction of LaCoO3 was measured at room temperature, 115 K, and 7 ˜ 4.2 K up to a maximum magnetic field of 150 T. The smooth dependence on the squared magnetic field and the first-order transition were observed at 115 K and 7 ˜ 4.2 K, respectively, reflecting the field-induced spin state evolution.

  5. Switchable dual-wavelength single-longitudinal-mode erbium-doped fiber laser using an inverse-Gaussian apodized fiber Bragg grating filter and a low-gain semiconductor optical amplifier.

    Science.gov (United States)

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

    2010-12-20

    We present a stable and switchable dual-wavelength erbium-doped fiber laser. In the ring cavity, an inverse-Gaussian apodized fiber Bragg grating serves as an ultranarrow dual-wavelength passband filter, a semiconductor optical amplifier biased in the low-gain regime reduces the gain competition of the two wavelengths, and a feedback fiber loop acts as a mode filter to guarantee a stable single-longitudinal-mode operation. Two lasing lines with a wavelength separation of approximately 0.1 nm are obtained experimentally. A microwave signal at 12.51 GHz is demonstrated by beating the dual wavelengths at a photodetector.

  6. UV writing of advanced Bragg gratings in optical waveguides

    DEFF Research Database (Denmark)

    Jensen, Jesper Bo Damm

    2002-01-01

    The subject of this ph.d. thesis is the fabrication of Bragg gratings in optical waveguides. During the study Bragg gratings were written in both planar waveguides and optical fibers using pulsed or continuous-wave lasers operating in the ultraviolet (UV) range. The main result is the development...... of the novel polarization control method for UV writing of Bragg gratings with advanced apodization profiles including phase shifts. The principle of the polarization control method relies on a spatial separation of the s- and p-polarized components of a linearly polarized UV beam corresponding to half...... were then translated into a polarizer angle profile and the Bragg grating were written using a pulsed excimer laser. Only optical fibers were used in this part of the thesis. The high quality planar waveguides used during the study were produced in the cleanroom facility at the Microelectronic Center...

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Fiber Bragg filters For laser- and multicore fibers

    Science.gov (United States)

    Becker, Martin; Elsmann, Tino; Lorenz, Adrian; Rothhardt, Manfred

    2017-05-01

    Fiber Bragg gratings (FBGs) have widespread applications in security, information, structural health monitoring, and biophotonics. In telecom applications, FBG inscription has reached a high level of maturity, but remains mainly limited to germanium doped photosensitive single mode fibers. Special applications, like filtering in light harvesting fibers or resonator mirrors for fiber lasers have to deal with special aspects which make the design and realization of FBGs a challenging task. One aspect is the extended wavelength range of these applications. Another aspect is the increasing demand to inscribe fiber Bragg gratings in non-photosensitive germanium-free fibers. Therefore, novel concepts of photosensitivity are proposed. Finally, to increase the amount of captured light the size of the fiber core and the numerical aperture have also to be increased. This goes along with multimode operation and prevents good filtering properties of Bragg gratings.

  13. 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.

  14. 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.

  15. Fiber Optic Temperature Sensors for Thermal Protection Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase 1, Intelligent Fiber Optic Systems Corporation (IFOS), in collaboration with North Carolina State University, successfully demonstrated a Fiber Bragg...

  16. 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.

  17. 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.

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

    Directory of Open Access Journals (Sweden)

    Mingyao Liu

    2013-01-01

    Full Text Available The change of spindle temperature field is an important factor which influences machining precision. Many methods of spindle temperature field measurement have been proposed. However, most of the methods are based on the electric temperature sensors. There exist some defects (e.g., anti-interference, multiplexing, and stability capacity are poor. To increase the temperature sensitivity and reduce strain sensitivity of the bare Fiber Bragg Grating (FBG sensor, a cassette packaged FBG sensor is proposed to measure spindle temperature field. The temperature characteristics of the packaged FBG sensor are studied by comparative experiment with traditional thermal resistor sensor. The experimental results show that the packaged FBG sensor has the same capacity of temperature measurement with the thermal resistor sensor but with more remarkable antiinterference. In the further measurement experiment of the temperature field, a spindle nonuniform temperature field is acquired by the calibrated FBG sensors. It indicates that the packaged FBG sensor can be used to measure the temperature field for the spindle of machine tool.

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

    Science.gov (United States)

    Choi, Sang-Jin; Mao, Wankai; Pan, Jae-Kyung

    2013-01-01

    We propose and experimentally demonstrate the novel radio-frequency (RF) interrogation of a fiber Bragg grating (FBG) sensor using bidirectional modulation of a Mach-Zehnder electro-optical modulator (MZ-EOM). Based on the microwave photonic technique and active detection, the transfer function of the proposed system was obtained, and the time delay was calculated from the change in the free spectral range (FSR) at different wavelengths over the optimal measuring range. The results show that the time delay and the wavelength variation have a good linear relationship, with a gradient of 9.31 ps/nm. An actual measurement taken with a sensing FBG for temperature variation shows the relationship with a gradient of 0.93 ps/10 °C. The developed system could be used for FBG temperature or strain sensing and other multiplexed sensor applications. PMID:23820744

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

    Directory of Open Access Journals (Sweden)

    Jae-Kyung Pan

    2013-07-01

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

  1. Fabrication of Optical Fiber Devices

    Science.gov (United States)

    Andres, Miguel V.

    In this paper we present the main research activities of the Laboratorio de Fibras Opticas del Instituto de Ciencia de los Materiales de la Universidad de Valencia. We show some of the main results obtained for devices based on tapered fibers, fiber Bragg gratings, acousto-optic effects and photonic crystal fibers.

  2. Optical fiber sensing technology in the pipeline industry

    Energy Technology Data Exchange (ETDEWEB)

    Braga, A.M.B.; Llerena, R.W.A. [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica]. E-mail: abraga@mec.puc-rio.br; roberan@mec.puc-rio.br; Valente, L.C.G.; Regazzi, R.D. [Gavea Sensors, Rio de Janeiro, RJ (Brazil)]. E-mail: guedes@gaveasensors.com; regazzi@gaveasensors.com

    2003-07-01

    This paper is concerned with applications of optical fiber sensors to pipeline monitoring. The basic principles of optical fiber sensors are briefly reviewed, with particular attention to fiber Bragg grating technology. Different potential applications in the pipeline industry are discussed, and an example of a pipeline strain monitoring system based on optical fiber Bragg grating sensors is presented. (author)

  3. A temperature-insensitive cladding-etched Fiber Bragg grating using a liquid mixture with a negative thermo-optic coefficient.

    Science.gov (United States)

    Kim, Kwang Taek; Kim, In Soo; Lee, Cherl-Hee; Lee, Jonghun

    2012-01-01

    To compensate for the temperature dependency of a standard FBG, a cladding-etched FBG immersed with a liquid mixture having a negative thermo-optic coefficient is presented, and its characteristics are investigated. The Bragg wavelength of the cladding-etched FBG is shifted counter to the direction of the Bragg wavelength shift of a conventional FBG according to the mixing ratio of glycerin to water; thus, the temperature-dependent Bragg wavelength shift was almost compensated by using a liquid mixture of water (50%) and glycerin (50%) having the negative thermo-optic coefficient of -5 × 10(-4) °C(-1).

  4. 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.

  5. A high speed, portable, multi-function, weigh-in-motion (WIM) sensing system and a high performance optical fiber Bragg grating (FBG) demodulator

    Science.gov (United States)

    Zhang, Hongtao; Wei, Zhanxiong; Fan, Lingling; Yang, Shangming; Wang, Pengfei; Cui, Hong-Liang

    2010-04-01

    A high speed, portable, multi-function WIM sensing system based on Fiber Bragg Grating (FBG) technology is reported in this paper. This system is developed to measure the total weight, the distribution of weight of vehicle in motion, the distance of wheel axles and the distance between left and right wheels. In this system, a temperature control system and a real-time compensation system are employed to eliminate the drifts of optical fiber Fabry-Pérot tunable filter. Carbon Fiber Laminated Composites are used in the sensor heads to obtain high reliability and sensitivity. The speed of tested vehicles is up to 20 mph, the full scope of measurement is 4000 lbs, and the static resolution of sensor head is 20 lbs. The demodulator has high speed (500 Hz) data collection, and high stability. The demodulator and the light source are packed into a 17'' rack style enclosure. The prototype has been tested respectively at Stevens' campus and Army base. Some experiences of avoiding the pitfalls in developing this system are also presented in this paper.

  6. 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.

  7. Design of DPSS based fiber bragg gratings and their application in all-optical encryption, OCDMA, optical steganography, and orthogonal-division multiplexing.

    Science.gov (United States)

    Djordjevic, Ivan B; Saleh, Alaa H; Küppers, Franko

    2014-05-05

    The future information infrastructure will be affected by limited bandwidth of optical networks, high energy consumption, heterogeneity of network segments, and security issues. As a solution to all problems, we advocate the use of both electrical basis functions (orthogonal prolate spheroidal basis functions) and optical basis functions, implemented as FBGs with orthogonal impulse response in addition to spatial modes. We design the Bragg gratings with orthogonal impulse responses by means of discrete layer peeling algorithm. The target impulse responses belong to the class of discrete prolate spheroidal sequences, which are mutually orthogonal regardless of the sequence order, while occupying the fixed bandwidth. We then design the corresponding encoders and decoders suitable for all-optical encryption, optical CDMA, optical steganography, and orthogonal-division multiplexing (ODM). Finally, we propose the spectral multiplexing-ODM-spatial multiplexing scheme enabling beyond 10 Pb/s serial optical transport networks.

  8. 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.

  9. Air core Bragg fibers for delivery of near-infrared laser radiation

    Science.gov (United States)

    Jelínek, Michal; Frank, Milan; Kubeček, Václav; Matějec, Vlastimil; Kašík, Ivan; Podrazký, Ondřej

    2014-12-01

    Optical fibers designed for high power laser radiation delivery represent important tools in medicine, solar systems, or industry. For such purposes several different types of glass optical fibers such as silica, sapphire, or chalcogenide ones as well as hollow-glass fibers, photonic crystal fibers and Bragg fibers have been investigated. Air-core Bragg fibers or photonic crystal fibers offer us the possibility of light transmission in a low dispersive material - air having a high damage threshold and small non-linear coefficient. However, preforms for drawing Bragg fibers can be fabricated by MCVD method similarly as preforms of standard silica fibers. In this paper we present fundamental characteristics of laboratory-designed and fabricated Bragg fibers with air cores intended for delivery of laser radiation at a wavelength range from 0.9 to 1.5 μm. Bragg fibers with different air core diameters of 5, 45 and 73 mm were prepared. The fiber core was surrounded by three pairs of circular Bragg layers. Each pair was composed of one layer with a high and one layer with a low refractive index with a contrast up to 0.03. Several laser sources emitting at 0.975, 1.06, and 1.55 μm were used as radiation sources. Attenuation coefficients, overall transmissions, bending losses, and spatial profiles of output beams from fibers were determined at these wavelengths. The lowest attenuation coefficient of 70 dB/km was determined for the 45 μm and 73 mm air-core fiber when radiation from a laser was launched into the fibers by using optical lenses. However, multimodal transmission has been observed in such condition. It has also been found that bending losses of such fibers are negligible for bending diameters higher than 15 mm.

  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. 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.

  12. 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.

  13. Optimizing optical Bragg scattering for single-photon frequency conversion

    CERN Document Server

    Lefrancois, Simon; Eggleton, Benjamin J

    2014-01-01

    We develop a systematic theory for optimising single-photon frequency conversion using optical Bragg scattering. The efficiency and phase-matching conditions for the desired Bragg scattering conversion as well as spurious scattering and modulation instability are identified. We find that third-order dispersion can suppress unwanted processes, while dispersion above the fourth order limits the maximum conversion efficiency. We apply the optimisation conditions to frequency conversion in highly nonlinear fiber, silicon nitride waveguides and silicon nanowires. Efficient conversion is confirmed using full numerical simulations. These design rules will assist the development of efficient quantum frequency conversion between multicolour single photon sources for integration in complex quantum networks.

  14. The effect of humidity on annealing of polymer optical fibre bragg gratings

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Nielsen, Kristian; Bang, Ole

    2015-01-01

    The effect of humidity on annealing of PMMA based microstructured polymer optical fiber (mPOF) Bragg gratings is studied. Polymer optical fibers (POFs) are annealed in order to release stress formed during the fabrication process. Un-annealed fibers will have high hysteresis and low sensitivity...

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. [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.

  20. 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.

  1. 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

  2. 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.

  3. Properties of Single Mode Polymer Optical Fiber

    Institute of Scientific and Technical Information of China (English)

    YANG Dong-xiao

    2003-01-01

    The density,dynamic modulus,Young's modulus,tensile strength,extension properties,Fourier transform infrared spectrum and differential scanning calorimetry have been measured and discussed for single mode polymethyl-methacrylate optical fiber.The results show that the fiber can provide large strain range for polymeric optical fiber Bragg gratings.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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...

  12. Preparation and Characterization of Bragg Fibers for Delivery of Laser Radiation at 1064 nm

    Directory of Open Access Journals (Sweden)

    V. Matejec

    2013-04-01

    Full Text Available Bragg fibers offer new performance for transmission of high laser energies over long distances. In this paper theoretical modeling, preparation and characterization of Bragg fibers for delivery laser radiation at 1064 nm are presented. Investigated Bragg fibers consist of the fiber core with a refractive index equal to that of silica which is surrounded by three pairs of circular layers. Each pair is composed of one layer with a high and one layer with a low refractive index and characterized by a refractive-index difference around 0.03. Propagation constants and radiation losses of the fundamental mode in such a structure were calculated on the basis of waveguide optics. Preforms of the Bragg fibers were prepared by the MCVD method using germanium dioxide, phosphorous pentoxide and fluorine as silica dopants. The fibers with a diameter of 170 m were drawn from the preforms. Refractive-index profiles, angular distributions of the output power and optical losses of the prepared fibers were measured. Results of testing the fibers for delivery radiation of a pulse Nd:YAG laser at 1064 nm are also shown.

  13. Simulations for analysis of the effect of ZnO-coated fiber grating structure to the Bragg wavelength

    Directory of Open Access Journals (Sweden)

    Roeksabutr, A.

    2003-11-01

    Full Text Available This paper theoretically analyses the characteristic of a fiber Bragg grating coated with piezoelectric zinc oxide (ZnO in order to operate under the acousto-optic effect by means of shifting Bragg wavelength. Simulations are performed to investigate the change of Bragg wavelength when varying parameters of the device structure. The results will be useful for consideration of device design as well as determination of the operating conditions.

  14. 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.

  15. 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.

  16. On the optimization of fiber Bragg grating optical sensor using genetic algorithm to monitor the strain of civil structure with high sensitivity

    Science.gov (United States)

    Kaur, Gurpreet; Kaler, Rajinder Singh; Kwatra, Naveen

    2016-08-01

    The effect of strain on civil structures is experimentally studied using fiber Bragg grating (FBG). The genetic algorithm is implemented to optimize the multiple parameters (Poisson's ratio, photoelastic coefficient P11, and photoelastic coefficient P12) of the proposed sensor. The optimized results helped in increasing the sensitivity in terms of wavelength shift. It is observed that the proposed FBG provides maximum wavelength shift of 38.16 nm with Poisson's ratio of 1.94, photoelastic coefficient P11 of 1.994, and photoelastic coefficient P12 of 1.8103.

  17. 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.

  18. 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.

  19. Multi-wavelength fiber ring laser based on semiconductor optical amplifier and sampled fiber Bragg grating in a Sagnac loop interferometer%基于半导体光放大器和取样光纤光栅结合Sagnac环的多波长光纤激光器

    Institute of Scientific and Technical Information of China (English)

    冯素春; 许鸥; 鲁韶华; 宁提纲; 简水生

    2009-01-01

    Multi-wavelength fiber ring laser based on the semiconductor optical amplifier(SOA)with sampled fiber Bragg grating(SFBG)in a Sagnac loop interferometer as the wavelength-selective filter is proposed.Four lasing wavelengths with 1.8 nm spacing have been generated stably at room temperature.The proposed laser has the advan-tages such as removal of the high-cost circulator,flexibility in channel-spacing tuning,and simple all-optical fiber configuration,which has potential applications in high-capacity wavelength-division-multiplexed(WDM)systems and mechanical sensors.

  20. 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.

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

    Science.gov (United States)

    Yüksel, Kivilcim; Pala, Deniz

    2016-06-01

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

  2. 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.

  3. Generation of tunable multi-wavelength optical short pulses using self-seeded Fabry-Perot laser diode and tilted multimode fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    Tongjian Cai; Yunqi Liu; Xiaobei Zhang; Tingyun Wang

    2011-01-01

    We experimentally demonstrate the simultaneous generation of tunable multi-wavelength picosecond laser pulses using a self-seeding configuration that consists of a gain-switched Fabry-Perot laser diode (FPLD)with an external cavity formed by a tilted multimode fiber Bragg grating.Dual- and triple-wavelength pulses are obtained and tuned in a flexible manner by changing the temperature of the FPLD.The side mode suppression ratio larger than 25 dB is achieved at different dual- and triple-wavelengths and the typical pulsewidth of the output pulses is ~70 ps.In the experiment, the wavelength separation can be narrowed to 0.57 nm.%@@ We experimentally demonstrate the simultaneous generation of tunable multi-wavelength picosecond laser pulses using a self-seeding configuration that consists of a gain-switched Fabry-Perot laser diode (FPLD)with an external cavity formed by a tilted multimode fiber Bragg grating.Dual-and triple-wavelength pulses are obtained and tuned in a flexible manner by changing the temperature of the FPLD.The side mode suppression ratio larger than 25 dB is achieved at different dual-and triple-wavelength8 and the typical pulsewidth of the output pulses is~70 ps.In the experiment, the wavelength separation can be narrowed to 0.57 nm.

  4. 870nm Bragg grating in single mode TOPAS microstructured polymer optical fibre

    DEFF Research Database (Denmark)

    Yuan, Wu; Webb, David J.; Kalli, Kyriacos

    2011-01-01

    We report the fabrication and characterization of a fiber Bragg grating (FBG) with 870 nm resonance wavelength in a single-mode TOPAS microstructured polymer optical fiber (mPOF). The grating has been UV-written with the phase-mask technique using a 325 nm HeCd laser. The static tensile strain...

  5. 870nm Bragg grating in single mode TOPAS microstructured polymer optical fibre

    DEFF Research Database (Denmark)

    Yuan, Wu; Webb, David J.; Kalli, Kyriacos;

    2011-01-01

    We report the fabrication and characterization of a fiber Bragg grating (FBG) with 870 nm resonance wavelength in a single-mode TOPAS microstructured polymer optical fiber (mPOF). The grating has been UV-written with the phase-mask technique using a 325 nm HeCd laser. The static tensile strain se...

  6. 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.

  7. Photonic bandgap narrowing in conical hollow core Bragg fibers

    Energy Technology Data Exchange (ETDEWEB)

    Ozturk, Fahri Emre; Yildirim, Adem; Kanik, Mehmet [UNAM-National Nanotechnology Research Center, Bilkent University, 06800 Ankara (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Bayindir, Mehmet, E-mail: bayindir@nano.org.tr [UNAM-National Nanotechnology Research Center, Bilkent University, 06800 Ankara (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Department of Physics, Bilkent University, 06800 Ankara (Turkey)

    2014-08-18

    We report the photonic bandgap engineering of Bragg fibers by controlling the thickness profile of the fiber during the thermal drawing. Conical hollow core Bragg fibers were produced by thermal drawing under a rapidly alternating load, which was applied by introducing steep changes to the fiber drawing speed. In conventional cylindrical Bragg fibers, light is guided by omnidirectional reflections from interior dielectric mirrors with a single quarter wave stack period. In conical fibers, the diameter reduction introduced a gradient of the quarter wave stack period along the length of the fiber. Therefore, the light guided within the fiber encountered slightly smaller dielectric layer thicknesses at each reflection, resulting in a progressive blueshift of the reflectance spectrum. As the reflectance spectrum shifts, longer wavelengths of the initial bandgap cease to be omnidirectionally reflected and exit through the cladding, which narrows the photonic bandgap. A narrow transmission bandwidth is particularly desirable in hollow waveguide mid-infrared sensing schemes, where broadband light is coupled to the fiber and the analyte vapor is introduced into the hollow core to measure infrared absorption. We carried out sensing simulations using the absorption spectrum of isopropyl alcohol vapor to demonstrate the importance of narrow bandgap fibers in chemical sensing applications.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    We present modeling and design of an all-optical MEMS Bragg grating (half-pitch of 125 nm) strain sensor for single-fiber distributed sensing. Low optical loss and the use of frequency modulation rather than amplitude modulation, makes this sensor better suited for distributed systems than...... mechanical amplification can be obtained if using an angled double beam micrometer scale MEMS structure, compared to conventional fiber Bragg grating sensors. An optimized design and fabrication process is presented....

  15. 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....

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Optical Fiber Spectroscopy

    Science.gov (United States)

    Buoncristiani, A. M.

    1999-01-01

    This is the final report of work done on NASA Grant NAG-1-443. The work covers the period from July 1, 1992 to December 1, 1998. During this period several distinct but related research studies and work tasks were undertaken. These different subjects are enumerated below with a description of the work done on each of them. The focus of the research was the development of optical fibers for use as distributed temperature and stress sensors. The initial concept was to utilize the utilize the temperature and stress dependence of emission from rare earth and transition metal ions substitutionally doped into crystalline or glass fibers. During the course of investigating this it became clear that fiber Bragg gratings provided a alternative for making the desired measurements and there was a shift of research focus on to include the photo-refractive properties of germano-silicate glasses used for most gratings and to the possibility of developing fiber laser sources for an integrated optical sensor in the research effort. During the course of this work several students from Christopher Newport University and other universities participated in this effort. Their names are listed below. Their participation was an important part of their education.

  6. 高可靠光纤布拉格光栅传感器网络设计%A High Reliabile Optic Fiber Bragg Grating Sensor Network Design

    Institute of Scientific and Technical Information of China (English)

    张晓丽; 梁大开; 芦吉云; 曾捷

    2011-01-01

    The fiber Bragg grating (FBG) sensor network which is used to monitor the external load position information of a certain aircraft wing box is researched in this paper. The forecast precision influence of the disabled sensor number to the external load position information is researched; Optical switch is introduced to overcome the shortcoming of the traditional FBG sensor network topology low reliability, proposing a higher reliabile network topology, and the reliability of the two types FBG network topologys are researched. The results indicate that the reliability of the new sensor network is superior to the traditional one obviously. The reliability of the two types network topologys is dependent on the failure rate of the single sensor. When the single component failure rate change between 0. 001 and 0.01, if the acceptable position forecast error of the external load is less than 5 mm, the failure rate of the new sensor network is reduced to 50% of the traditional one; if the acceptable position forecast error of the external load is less than 10 mm, the failure rate of the new sensor network is reduced to 12.5% of the traditional one at least.%对采用光纤布拉格光栅(FBG)传感器网络监测某飞机机翼盒段外加载荷位置信息进行了研究.研究了FBG传感器网络中传感器失效对外加载荷位置识别精度的影响程度;针对传统FBG传感器网络拓扑结构可靠性低的缺点,引入光开关,设计了一种具有更高可靠性的传感器网络拓扑结构,并对这两种网络结构的可靠性进行了研究.结果表明,新传感器网络的可靠性明显高于传统传感器网络的可靠性.单个传感器的失效概率不同,两种传感器网络可靠性差别也不同;当单个元器件的失效概率在0.001~0.01之间变动时,若系统允许外加载荷位置识别误差在5 mm内,则新传感器网络的失效率降为传统网络失效率的50%;若系统允许外加载荷位置识别误差在10 mm

  7. 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.

  8. Effect of polymer coating on leakage losses in Bragg fibers.

    Science.gov (United States)

    Uspenskii, Yu A; Uzorin, E E; Vinogradov, A V; Likhachev, M E; Semjonov, S L; Bubnov, M M; Dianov, E M; Jamier, R; Février, S

    2007-05-15

    It is found that the reflection of leaky radiation from the interface between the outer silica cladding and the coating polymer greatly modifies the loss spectrum of Bragg fibers. A simple model that describes this effect is proposed and confirmed by measurement and computation.

  9. 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.

  10. Squeezed hollow-core photonic Bragg fiber for surface sensing applications.

    Science.gov (United States)

    Li, Jingwen; Qu, Hang; Skorobogatiy, Maksim

    2016-07-11

    We propose to use squeezed hollow-core photonic bandgap Bragg fibers for surface sensing applications. We demonstrate theoretically and confirm experimentally that squeezing a section of the Bragg fiber core increases overlap between the optical fields of the core guided modes and the modes bound to the sensing layer, thus, significantly enhancing their interaction via anticrossing phenomenon, which, in turn, enhances surface sensitivity of the fiber sensor. As a practical demonstration, we apply our fiber sensor to in situ monitoring of the dissolution dynamics of a sub-micron-thick polyvinyl butyral (PVB) film coated on the surface of the liquid-filled Bragg fiber core. Strong spectral shift is observed during the dissolution of the PVB film, and a surface spectral sensitivity of ~0.07nm/nm is achieved experimentally with aqueous analytes. The proposed fiber sensor offers a new sensing modality and opens new sensing applications for photonic bandgap fibers, such as real-time detection of binding and affinity, study of kinetics, etc. for a range of chemical and biological samples.

  11. 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.

  12. 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.

  13. 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.

  14. Localized topological states in Bragg multihelicoidal fibers with twist defects

    Science.gov (United States)

    Alexeyev, C. N.; Lapin, B. P.; Milione, G.; Yavorsky, M. A.

    2016-06-01

    We have studied the influence of a twist defect in multihelicoidal Bragg fibers on the emerging of localized defect modes. We have shown that if such a fiber is excited with a Gaussian beam this leads to the appearance of a defect-localized topological state, whose topological charge coincides with the order of rotational symmetry of the fiber's refractive index. We have shown that this effect has a pronounced crossover behavior. We have also formulated a principle of creating the systems that can nestle defect-localized topologically charged modes. According to this principle, such systems have to possess topological activity, that is, the ability to change the topological charge of the incoming field, and operate in the Bragg regime.

  15. 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.

  16. 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.

  17. Optical Properties of Topological Insulator Bragg Gratings

    CERN Document Server

    Crosse, J A

    2015-01-01

    Using the transfer matrix formalism, we study the transmission properties of a Bragg grating constructed from a layered axionic material. Such a material can be realized by a topological insulator subject to a time-symmetry breaking perturbation, such as an external magnetic field or surface magnetic impurities. Whilst the reflective properties of the structure are only negligibly changed by the presence of the axionic material, the grating induces Faraday and Kerr rotations in the transmitted and reflected light, respectively. These rotations are proportional to the number of layers and the strength of the time-symmetry breaking perturbation. In areas of low reflectivity the rotation angle of TE polarization decreases with increasing incidence angle while the TM polarization increases with increasing incidence angle with the converse occurring in areas of high reflectivity. The formalism and results will be useful in the development of optical and photonic devices based on topological insulators, devices whi...

  18. 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.

  19. 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.

  20. Dimensional Crossover in Bragg Scattering from an Optical Lattice

    CERN Document Server

    Slama, S; Ludewig, A; Köhler, M; Zimmermann, C; Courteille, P W; Courteille, Ph.W.

    2005-01-01

    We study Bragg scattering at 1D optical lattices. Cold atoms are confined by the optical dipole force at the antinodes of a standing wave generated inside a laser-driven high-finesse cavity. The atoms arrange themselves into a chain of pancake-shaped layers located at the antinodes of the standing wave. Laser light incident on this chain is partially Bragg-reflected. We observe an angular dependence of this Bragg reflection which is different to what is known from crystalline solids. In solids the scattering layers can be taken to be infinitely spread (3D limit). This is not generally true for an optical lattice consistent of a 1D linear chain of point-like scattering sites. By an explicit structure factor calculation we derive a generalized Bragg condition, which is valid in the intermediate regime. This enables us to determine the aspect ratio of the atomic lattice from the angular dependance of the Bragg scattered light.

  1. Optical fibre Bragg grating recorded in TOPAS cyclic olefin copolymer

    DEFF Research Database (Denmark)

    Johnson, I.P.; Yuan, Scott Wu; Stefani, Alessio

    2011-01-01

    A report is presented on the inscription of a fibre Bragg grating into a microstructured polymer optical fibre fabricated from TOPAS cyclic olefin copolymer. This material offers two important advantages over poly (methyl methacrylate), which up to now has formed the basis for polymer fibre Bragg...

  2. Engineering modes in optical fibers with metamaterial

    DEFF Research Database (Denmark)

    Yan, Min; Mortensen, Asger; Qiu, Min

    2009-01-01

    as an extension from the previously much publicized microstructured optical fibers. Metamaterials can have optical properties not obtainable in naturally existing materials, including artificial anisotropy as well as graded material properties. Therefore, incorporation of metamaterial in optical fiber designs can...... produce a new range of fiber properties. With a particular example, we will show how mode discrimination can be achieved in a multimode Bragg fiber with the help of metamaterial. We also look into the mean field theory as well as Maxwell-Garnett theory for homogenizing a fine metamaterial structure...

  3. 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.

  4. Engineering modes in optical fibers with metamaterial

    Institute of Scientific and Technical Information of China (English)

    Min YAN; Niels Asger MORTENSEN; Min QIU

    2009-01-01

    In this paper, we report a preliminary theoret-ical study on optical fibers with fine material inclusions whose geometrical inhomogeneity is almost indistinguish-able by the operating wavelength. We refer to such fibers as metamaterial optical fibers, which can conceptually be considered as an extension from the previously much publicized microstructured optical fibers. Metamaterials can have optical properties not obtainable in naturally existing materials, including artificial anisotropy as well as graded material properties. Therefore, incorporation of metamaterial in optical fiber designs can produce a new range of fiber properties. With a particular example, we will show how mode discrimination can be achieved in a multimode Bragg fiber with the help of metamaterial. We also look into the mean field theory as well as Maxwell-Garner theory for homogenizing a fine metamaterial structure to a homogeneous one. The accuracies of the two homogenization approaches are compared with full-structure calculation.

  5. 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.

  6. 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.

  7. 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.

  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. Optofluidic magnetometer developed in a microstructured optical fiber.

    Science.gov (United States)

    Candiani, A; Konstantaki, M; Margulis, W; Pissadakis, S

    2012-11-01

    A directional, in-fiber optofluidic magnetometer based on a microstructured optical fiber (MOF) Bragg-grating infiltrated with a ferrofluidic defect is presented. Upon application of a magnetic field, the ferrofluidic defect moves along the length of the MOF Bragg grating, modifying its reflection spectrum. The magnetometer is capable of measuring magnetic fields from 317 to 2500 G. The operational principle of such in-fiber magnetic field probe allows the elaboration of directional measurements of the magnetic field flux.

  10. Supercontinuum generation in a Bragg fiber:a novel proposal

    Institute of Scientific and Technical Information of China (English)

    Bishnu P.Pal; Sonali Dasgupta; M.R.Shenoy; Alexej Sysoliatin

    2006-01-01

    @@ We propose a silica-core dispersion-decreasing Bragg fiber (DDBF) of mode effective area as large as 55 μm2 for supercontinuum (SC) generation at the pump wavelength of 1 060 nm.Using a fast and simple matrix method to model propagation in the DDBF,we have presented a general criterion to obtain the shortest length of the DDBF that would result in a broad SC spectrum.The proposed DDBF design should be amenable for reproducible fabrication through the well-developed MCVD fiber manufacturing technology and the concept has potential for realization as a practical device.

  11. 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.

  12. 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.

  13. 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.

  14. Zeonex Microstructured Polymer Optical Fibre Bragg Grating Sensor

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Fasano, Andrea; Markos, Christos

    2016-01-01

    We fabricated an endlessly single mode and humidity insensitive Zeonex microstructured polymer optical fibre (mPOF) for fibre Bragg grating (FBG) temperature and strain sensors. We inscribed and characterise FBGs in Zeonex mPOF for the first time.......We fabricated an endlessly single mode and humidity insensitive Zeonex microstructured polymer optical fibre (mPOF) for fibre Bragg grating (FBG) temperature and strain sensors. We inscribed and characterise FBGs in Zeonex mPOF for the first time....

  15. 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.

  16. 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.

  17. Fiber Optic-Based Refractive Index Sensing at INESC Porto

    Science.gov (United States)

    Jorge, Pedro A. S.; Silva, Susana O.; Gouveia, Carlos; Tafulo, Paula; Coelho, Luis; Caldas, Paulo; Viegas, Diana; Rego, Gaspar; Baptista, José M.; Santos, José L.; Frazão, Orlando

    2012-01-01

    A review of refractive index measurement based on different types of optical fiber sensor configurations and techniques is presented. It addresses the main developments in the area, with particular focus on results obtained at INESC Porto, Portugal. The optical fiber sensing structures studied include those based on Bragg and long period gratings, on micro-interferometers, on plasmonic effects in fibers and on multimode interference in a large spectrum of standard and microstructured optical fibers. PMID:22969405

  18. Bragg-Fresnel optics: New field of applications

    Energy Technology Data Exchange (ETDEWEB)

    Snigirev, A. [ESRF, Grenoble (France)

    1997-02-01

    Bragg-Fresnel Optics shows excellent compatibility with the third generation synchrotron radiation sources such as ESRF and is capable of obtaining monochromatic submicron focal spots with 10{sup 8}-10{sup 9} photons/sec in an energy bandwidth of 10{sup -4}-10{sup -6} and in a photon energy range between 2-100 keV. New types of Bragg-Fresnel lenses like modified, ion implanted, bent and acoustically modulated were tested. Microprobe techniques like microdiffraction and microfluorescence based on Bragg-Fresnel optics were realised at the ESRF beamlines. Excellent parameters of the X-ray beam at the ESRF in terms of low emittance and quite small angular source size allow for Bragg-Fresnel optics to occupy new fields of applications such as high resolution diffraction, holography, interferometry and phase contrast imaging.

  19. Fiber Optic Thermal Detection of Composite Delaminations

    Science.gov (United States)

    Wu, Meng-Chou; Winfree, William P.

    2011-01-01

    A recently developed technique is presented for thermographic detection of delaminations in composites by performing temperature measurements with fiber optic Bragg gratings. A single optical fiber with multiple Bragg gratings employed as surface temperature sensors was bonded to the surface of a composite with subsurface defects. The investigated structure was a 10-ply composite specimen with prefabricated delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The data obtained from grating sensors were analyzed with thermal modeling techniques of conventional thermography to reveal particular characteristics of the interested areas. Results were compared and found to be consistent with the calculations using numerical simulation techniques. Also discussed are methods including various heating sources and patterns, and their limitations for performing in-situ structural health monitoring.

  20. Fiber Optic Thermal Health Monitoring of Composites

    Science.gov (United States)

    Wu, Meng-Chou; Winfree, William P.; Moore, Jason P.

    2010-01-01

    A recently developed technique is presented for thermographic detection of flaws in composite materials by performing temperature measurements with fiber optic Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of composites with subsurface defects. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The data obtained from grating sensors were analyzed with thermal modeling techniques of conventional thermography to reveal particular characteristics of the interested areas. Results were compared with the calculations using numerical simulation techniques. Methods and limitations for performing in-situ structural health monitoring are discussed.

  1. Broadband transmission in hollow-core Bragg fibers with geometrically distributed multilayered cladding.

    Science.gov (United States)

    Hu, Dora Juan Juan; Alagappan, Gandhi; Yeo, Yong-Kee; Shum, Perry Ping; Wu, Ping

    2010-08-30

    For the first time, the quasiperiodic Bragg fibers with geometrically distributed multilayered cladding are proposed and analyzed. We demonstrate that hollow-core Bragg fibers with quasiperiodic dielectric multilayer cladding can achieve low loss transmission over a broadband wavelength range of more than an octave (from 0.81 μm to 1.7 μm). The periods of the Bragg blocks follows a geometrical progression with a common ratio rcladding can significantly modify the characteristics of the fiber, leading to a broadening of the guiding range compared to a hollow Bragg fiber with uniform periodic multilayer cladding structure. In general, a larger r value results in a broader guiding range. More Bragg blocks in the cladding and more unit cells in each Bragg block lead to a lower fiber modal loss.

  2. 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.

  3. Curved Piezoelectric Actuators for Stretching Optical Fibers

    Science.gov (United States)

    Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

    2008-01-01

    Assemblies containing curved piezoceramic fiber composite actuators have been invented as means of stretching optical fibers by amounts that depend on applied drive voltages. Piezoceramic fiber composite actuators are conventionally manufactured as sheets or ribbons that are flat and flexible, but can be made curved to obtain load-carrying ability and displacement greater than those obtainable from the flat versions. In the primary embodiment of this invention, piezoceramic fibers are oriented parallel to the direction of longitudinal displacement of the actuators so that application of drive voltage causes the actuator to flatten, producing maximum motion. Actuator motion can be transmitted to the optical fiber by use of hinges and clamp blocks. In the original application of this invention, the optical fiber contains a Bragg grating and the purpose of the controlled stretching of the fiber is to tune the grating as part of a small, lightweight, mode-hop-free, rapidly tunable laser for demodulating strain in Bragg-grating strain-measurement optical fibers attached to structures. The invention could also be used to apply controllable tensile force or displacement to an object other than an optical fiber.

  4. 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.

  5. 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.

  6. Compact Single-Mode Distributed Bragg Reflector Fiber Laser

    Institute of Scientific and Technical Information of China (English)

    XUE Yi-Yuan; AN Hong-Lin; FU Li-Bin; LIN Xiang-Zhi; LIU Hong-Du

    2000-01-01

    A compact single-mode distributed Bragg reflector (DBR) fiber laser with narrow spectral linewidth is investigated. Firstly, based on our theoretical analysis the single longitudinal mode operation domain is obtained. Then, a single-mode DBR fiber laser of 7.9cm long with master oscillator power amplifier (MOPA) configuration is designed and constructed to operate in the single-mode domain. The fiber laser is pumped by a semiconductor laser at 975.5nm. The master oscillator operates at 1556.91 nm with a cw output power of 1.43mW for a pump power of 55.35 mW. Its slope efficiency is 2.7% and the spectral linewidth is less than 1.2MHz (instrument resolution limited). With the MOPA configuration the laser output power and slope efficiency are increased to 7.8mW and 16.9%, respectively.

  7. 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.

  8. 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.

  9. 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...

  10. 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.

  11. Fiber Optics Technology.

    Science.gov (United States)

    Burns, William E.

    1986-01-01

    Discusses various applications of fiber optics technology: information systems, industrial robots, medicine, television, transportation, and training. Types of jobs that will be available with fiber optics training (such as electricians and telephone cable installers and splicers) are examined. (CT)

  12. Fiber Optics Instrumentation Development

    Science.gov (United States)

    Chan, Patrick Hon Man; Parker, Allen R., Jr.; Richards, W. Lance

    2010-01-01

    This is a general presentation of fiber optics instrumentation development work being conducted at NASA Dryden for the past 10 years and recent achievements in the field of fiber optics strain sensors.

  13. Fiber optical artificial nose for the food industry

    Science.gov (United States)

    Mahmoud, Mohamed

    2003-04-01

    An artificial nose has been attractive for scientific research and the food industry. This paper proposes that the detection and recognition of odours or chemicals concentrate can be achieved by means of passive and compact size fiber optic sensors (Fiber Bragg Gratings Technology) that will form an olfactory sensor array and a fuzzy logic algorithm that will form the recognition artificial intelligence. The mathematical model of the fiber Bragg gratings olfactory sensor is developed and the design model of the artificial fiber optic nose is introduced.

  14. 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.

  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. Optical fiber sensors measurement system and special fibers improvement

    Science.gov (United States)

    Jelinek, Michal; Hrabina, Jan; Hola, Miroslava; Hucl, Vaclav; Cizek, Martin; Rerucha, Simon; Lazar, Josef; Mikel, Bretislav

    2017-06-01

    We present method for the improvement of the measurement accuracy in the optical frequency spectra measurements based on tunable optical filters. The optical filter was used during the design and realization of the measurement system for the inspection of the fiber Bragg gratings. The system incorporates a reference block for the compensation of environmental influences, an interferometric verification subsystem and a PC - based control software implemented in LabView. The preliminary experimental verification of the measurement principle and the measurement system functionality were carried out on a testing rig with a specially prepared concrete console in the UJV Řež. The presented system is the laboratory version of the special nuclear power plant containment shape deformation measurement system which was installed in the power plant Temelin during last year. On the base of this research we started with preparation other optical fiber sensors to nuclear power plants measurement. These sensors will be based on the microstructured and polarization maintaining optical fibers. We started with development of new methods and techniques of the splicing and shaping optical fibers. We are able to made optical tapers from ultra-short called adiabatic with length around 400 um up to long tapers with length up to 6 millimeters. We developed new techniques of splicing standard Single Mode (SM) and Multimode (MM) optical fibers and splicing of optical fibers with different diameters in the wavelength range from 532 to 1550 nm. Together with development these techniques we prepared other techniques to splicing and shaping special optical fibers like as Polarization-Maintaining (PM) or hollow core Photonic Crystal Fiber (PCF) and theirs cross splicing methods with focus to minimalize backreflection and attenuation. The splicing special optical fibers especially PCF fibers with standard telecommunication and other SM fibers can be done by our developed techniques. Adjustment

  17. Two Fiber Optical Fiber Thermometry

    Science.gov (United States)

    Jones, Mathew R.; Farmer, Jeffery T.; Breeding, Shawn P.

    2000-01-01

    An optical fiber thermometer consists of an optical fiber whose sensing tip is given a metallic coating. The sensing tip of the fiber is essentially an isothermal cavity, so the emission from this cavity will be approximately equal to the emission from a blackbody. Temperature readings are obtained by measuring the spectral radiative heat flux at the end of the fiber at two wavelengths. The ratio of these measurements and Planck's Law are used to infer the temperature at the sensing tip. Optical fiber thermometers have high accuracy, excellent long-term stability and are immune to electromagnetic interference. In addition, they can be operated for extended periods without requiring re-calibration. For these reasons. it is desirable to use optical fiber thermometers in environments such as the International Space Station. However, it has recently been shown that temperature readings are corrupted by emission from the fiber when extended portions of the probe are exposed to elevated temperatures. This paper will describe several ways in which the reading from a second fiber can be used to correct the corrupted temperature measurements. The accuracy and sensitivity to measurement uncertainty will be presented for each method.

  18. 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.

  19. Tensile strain and temperature characterization of FBGs in preannealed Polymer Optical Fibers

    DEFF Research Database (Denmark)

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

    2010-01-01

    Our thermal and tensile strain experiments show that fiber Bragg gratings (FBGs) in preannealed polymer optical fibers (POFs) can offer more stable performance and extend the operating temperature and strain range without hysteresis.......Our thermal and tensile strain experiments show that fiber Bragg gratings (FBGs) in preannealed polymer optical fibers (POFs) can offer more stable performance and extend the operating temperature and strain range without hysteresis....

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Fiber optics engineering

    CERN Document Server

    Azadeh, Mohammad

    2009-01-01

    Covering fiber optics from an engineering perspective, this text emphasizes data conversion between electrical and optical domains. Techniques to improve the fidelity of this conversion (from electrical to optical domain, and vice versa) are also covered.

  8. Role of hydrogen loading and glass composition on the defects generated by the femtosecond laser writing process of fiber Bragg gratings

    NARCIS (Netherlands)

    Troy, N.; Smelser, C.W.; Krol, D.M.

    2012-01-01

    The creation of fiber Bragg gratings (FBGs) in optical fibers by laser irradiation causes the formation of defects in the modified glass. We have used confocal fluorescence spectroscopy to identify the location and types of defects formed after writing FBGs with the femtosecond laser phase mask tech

  9. The Fiber Optic Connection.

    Science.gov (United States)

    Reese, Susan

    2003-01-01

    Describes the fiber optics programs at the Career and Technical Center in Berlin, Pennsylvania and the Charles S. Monroe Technology Center in Loudoun County, Virginia. Discusses the involvement of the Fiber Optic Association with education, research and development, manufacturing, sales, distribution, installation, and maintenance of fiber optic…

  10. Development of variable-magnification X-ray Bragg optics.

    Science.gov (United States)

    Hirano, Keiichi; Yamashita, Yoshiki; Takahashi, Yumiko; Sugiyama, Hiroshi

    2015-07-01

    A novel X-ray Bragg optics is proposed for variable-magnification of an X-ray beam. This X-ray Bragg optics is composed of two magnifiers in a crossed arrangement, and the magnification factor, M, is controlled through the azimuth angle of each magnifier. The basic properties of the X-ray optics such as the magnification factor, image transformation matrix and intrinsic acceptance angle are described based on the dynamical theory of X-ray diffraction. The feasibility of the variable-magnification X-ray Bragg optics was verified at the vertical-wiggler beamline BL-14B of the Photon Factory. For X-ray Bragg magnifiers, Si(220) crystals with an asymmetric angle of 14° were used. The magnification factor was calculated to be tunable between 0.1 and 10.0 at a wavelength of 0.112 nm. At various magnification factors (M ≥ 1.0), X-ray images of a nylon mesh were observed with an air-cooled X-ray CCD camera. Image deformation caused by the optics could be corrected by using a 2 × 2 transformation matrix and bilinear interpolation method. Not only absorption-contrast but also edge-contrast due to Fresnel diffraction was observed in the magnified images.

  11. Ultra Small Integrated Optical Fiber Sensing System

    Directory of Open Access Journals (Sweden)

    Peter Van Daele

    2012-09-01

    Full Text Available This paper introduces a revolutionary way to interrogate optical fiber sensors based on fiber Bragg gratings (FBGs and to integrate the necessary driving optoelectronic components with the sensor elements. Low-cost optoelectronic chips are used to interrogate the optical fibers, creating a portable dynamic sensing system as an alternative for the traditionally bulky and expensive fiber sensor interrogation units. The possibility to embed these laser and detector chips is demonstrated resulting in an ultra thin flexible optoelectronic package of only 40 μm, provided with an integrated planar fiber pigtail. The result is a fully embedded flexible sensing system with a thickness of only 1 mm, based on a single Vertical-Cavity Surface-Emitting Laser (VCSEL, fiber sensor and photodetector chip. Temperature, strain and electrodynamic shaking tests have been performed on our system, not limited to static read-out measurements but dynamically reconstructing full spectral information datasets.

  12. Absolute Measurement Fiber-optic Sensors in Large Structural Monitoring

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The security of civil engineering is an important task due to the economic, social and environmental significance. Compared with conventional sensors, the optical fiber sensors have their unique characteristics.Being durable, stable and insensitive to external perturbations,they are particular interesting for the long-term monitoring of civil structures.Focus is on absolute measurement optical fiber sensors, which are emerging from the monitoring large structural, including SOFO system, F-P optical fiber sensors, and fiber Bragg grating sensors. The principle, characteristic and application of these three kinds of optical fiber sensors are described together with their future prospects.

  13. 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.

  14. 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.

  15. 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.

  16. Optical Fiber Fusion Splicing

    CERN Document Server

    Yablon, Andrew D

    2005-01-01

    This book is an up-to-date treatment of optical fiber fusion splicing incorporating all the recent innovations in the field. It provides a toolbox of general strategies and specific techniques that the reader can apply when optimizing fusion splices between novel fibers. It specifically addresses considerations important for fusion splicing of contemporary specialty fibers including dispersion compensating fiber, erbium-doped gain fiber, polarization maintaining fiber, and microstructured fiber. Finally, it discusses the future of optical fiber fusion splicing including silica and non-silica based optical fibers as well as the trend toward increasing automation. Whilst serving as a self-contained reference work, abundant citations from the technical literature will enable readers to readily locate primary sources.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind P

    2001-01-01

    The Optical Society of America (OSA) and SPIE - The International Society for Optical Engineering have awarded Govind Agrawal with an honorable mention for the Joseph W. Goodman Book Writing Award for his work on Nonlinear Fiber Optics, 3rd edition.Nonlinear Fiber Optics, 3rd Edition, provides a comprehensive and up-to-date account of the nonlinear phenomena occurring inside optical fibers. It retains most of the material that appeared in the first edition, with the exception of Chapter 6, which is now devoted to the polarization effects relevant for light propagation in optical

  4. 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.

  5. 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

  6. 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

  7. Micro-deformation measurement on the concrete roadway surface slabs using Fiber Bragg Grating and analysis by computational simulation

    Energy Technology Data Exchange (ETDEWEB)

    Serpa, C M; Gomez, N D [Instituto Tecnologico Metropolitano Institucion Universitaria (ITM), Medellin A. A. 54954 (Colombia); Velez, F J, E-mail: claudiaserpa@itm.edu.co [Universidad EAFIT, Medellin (Colombia)

    2011-01-01

    This work shows a non-invasive method for micro-deformation measurements on concrete structures using Bragg grating sensors in optical fibers adhered to the surface. We present the measurements on roadway slabs under a load of 10 kN, and we find an approximated ratio of 2:1 between the deformation registered by the sensors and the values from a computational simulation with the finite element method. We propose the use of these sensors for structural monitoring of the slabs and this installation shape for avoiding bends that can damage the edges in the optical fiber in embebed sensors in vertical shape.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. A fiber Bragg based semi distributed pressure sensor system for in-vivo vascular applications

    NARCIS (Netherlands)

    Nieuwland, R.A.; Cheng, L.K.; Lemmen, M.H.J.; Oostenbrink, R.H.; Harmsma, P.J.; Schreuder, J.J.

    2014-01-01

    An overview of a fiber Bragg based sensor system, developed for in-vivo vascular pressure and temperature sensing, is presented. The focus is on sensor miniaturization and interrogator optimization to reach a viable sensor system.

  1. 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.

  2. 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.

  3. Optical fiber gas sensing system based on FBG filtering

    Science.gov (United States)

    Wang, Shutao

    2008-10-01

    An optical fiber gas sensing system based on the law of Beer-Lambert is designed to determine the concentration of gas. This technique relies on the fact that the target gas has a unique, well-defined absorption characteristic within the infrared region of electromagnetic spectrum. The narrow-band filtering characteristic of optical fiber Bragg grating is used to produce the narrow spectrum light signal. An aspheric objective optical fiber collimator is used in the system as an optical fiber gas sensing detector to improve the sensitivity and stability. Experimental results show there is a high measuring sensitivity at 0.01%, and the measuring range goes beyond 5%.

  4. 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.

  5. Python fiber optic seal

    Energy Technology Data Exchange (ETDEWEB)

    Ystesund, K.; Bartberger, J.; Brusseau, C.; Fleming, P.; Insch, K.; Tolk, K.

    1993-08-01

    Sandia National Laboratories has developed a high security fiber optic seal that incorporates tamper resistance features that are not available in commercial fiber optic seals. The Python Seal is a passive fiber optic loop seal designed to give indication of unauthorized entry. The seal includes a fingerprint feature that provides seal identity information in addition to the unique fiber optic pattern created when the seal is installed. The fiber optic cable used for the seal loop is produced with tamper resistant features that increase the difficulty of attacking that component of a seal. A Seal Reader has been developed that will record the seal signature and the fingerprint feature of the seal. A Correlator software program then compares seal images to establish a match or mismatch. SNL is also developing a Polaroid reader to permit hard copies of the seal patterns to be obtained directly from the seal.

  6. 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.

  7. 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.

  8. 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.

  9. 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 ...

  10. Switchable and tunable erbium-doped fiber lasers using a hollow-core Bragg fiber

    Science.gov (United States)

    Zhao, Tanglin; Lian, Zhenggang; Wang, Xin; Shen, Yan; Lou, Shuqin

    2016-11-01

    A switchable and tunable erbium-doped fiber laser (EDFL) is proposed and experimentally demonstrated in this paper. A novel comb filter, which consists of a section of hollow-core Bragg fiber cascaded with Sagnac loop based on a polarization-maintaining fiber (PMF), is developed to suppress the mode competition in the EDFL. By carefully adjusting the polarization controllers, switchable and tunable single- or dual-wavelength lasing outputs with side-mode suppression ratios as high as 50 dB can be achieved. Single-wavelength lasing outputs with a 3 dB linewidth of 0.02 nm can be tuned within the wavelength range from 1562.4 nm to 1565.8 nm. Two kinds of dual-wavelength lasing outputs with different wavelength intervals of 1 nm and 2.1 nm can be obtained and the corresponding tunable wavelength range is 0.5 nm. Moreover, the wavelength shift and peak power fluctuation of both the single- and dual-wavelength lasing outputs are less than 0.1 nm and 2 dB over half an hour at room temperature, which indicates that the proposed fiber laser has good stability. To the best of our knowledge, it is the first time that a hollow-core Bragg fiber has been used as a comb filter in the EDFL.

  11. Fiber optic spanner

    Science.gov (United States)

    Black, Bryan; Mohanty, Samarendra

    2011-10-01

    Rotation is a fundamental function in nano/biotechnology and is being useful in a host of applications such as pumping of fluid flow in microfluidic channels for transport of micro/nano samples. Further, controlled rotation of single cell or microscopic object is useful for tomographic imaging. Though conventional microscope objective based laser spanners (based on transfer of spin or orbital angular momentum) have been used in the past, they are limited by the short working distance of the microscope objective. Here, we demonstrate development of a fiber optic spanner for rotation of microscopic objects using single-mode fiber optics. Fiber-optic trapping and simultaneous rotation of pin-wheel structure around axis perpendicular to fiber-optic axis was achieved using the fiber optic spanner. By adjusting the laser beam power, rotation speed of the trapped object and thus the microfluidic flow could be controlled. Since this method does not require special optical or structural properties of the sample to be rotated, three-dimensional rotation of a spherical cell could also be controlled. Further, using the fiber optic spanner, array of red blood cells could be assembled and actuated to generate vortex motion. Fiber optical trapping and spinning will enable physical and spectroscopic analysis of microscopic objects in solution and also find potential applications in lab- on-a-chip devices.

  12. Guided Wave and Damage Detection in Composite Laminates Using Different Fiber Optic Sensors

    OpenAIRE

    Fucai Li; Hideaki Murayama; Kazuro Kageyama; Takehiro Shirai

    2009-01-01

    Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber r...

  13. Optical fiber sensing based on reflection laser spectroscopy.

    Science.gov (United States)

    Gagliardi, Gianluca; Salza, Mario; Ferraro, Pietro; Chehura, Edmond; Tatam, Ralph P; Gangopadhyay, Tarun K; Ballard, Nicholas; Paz-Soldan, Daniel; Barnes, Jack A; Loock, Hans-Peter; Lam, Timothy T-Y; Chow, Jong H; De Natale, Paolo

    2010-01-01

    An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs) and FBG resonators built in fibers of different types are used for strain, temperature and acceleration measurements using heterodyne-detection and optical frequency-locking techniques. Silica fiber-ring cavities are used for chemical sensing based on evanescent-wave spectroscopy. Various arrangements for signal recovery and noise reduction, as an extension of most typical spectroscopic techniques, are illustrated and results on detection performances are presented.

  14. Optical Fiber Sensing Based on Reflection Laser Spectroscopy

    Directory of Open Access Journals (Sweden)

    Gianluca Gagliardi

    2010-03-01

    Full Text Available An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs and FBG resonators built in fibers of different types are used for strain, temperature and acceleration measurements using heterodyne-detection and optical frequency-locking techniques. Silica fiber-ring cavities are used for chemical sensing based on evanescent-wave spectroscopy. Various arrangements for signal recovery and noise reduction, as an extension of most typical spectroscopic techniques, are illustrated and results on detection performances are presented.

  15. A new monitoring method of cable tension of cable-stayed bridge-fiber Bragg grating method

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu-she; DU Yan-liang; NING Chen-xiao

    2005-01-01

    A new on-line monitoring method based on fiber Bragg grating (FBG) for cable tension of cable-stayed bridge was introduced. The major structure of sensing head using in the test of cable tension is elastic annular. The FBG is attached inflexibility to the exterior surface of annulus and form straight-through sensing head. Sensing headis installed between the anchor device and stow-board of funiculus holes of the cable-stayed bridge. Accompany with the change of the outside pressure, the Bragg center reflective wavelength of optical fiber grating changed correspondingly. According to this characteristic, through demodulating the△λ, the value of the cable tension can be determined. The experiment results and the theory indicate that the test system has simple structure, good stability and linear,wide response capacity, and has no special request for tester, The measurement method for the test of ca ble tension is practical and effective.

  16. 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.

  17. 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.

  18. Fiber optics standard dictionary

    CERN Document Server

    Weik, Martin H

    1997-01-01

    Fiber Optics Vocabulary Development In 1979, the National Communications System published Technical InfonnationBulle­ tin TB 79-1, Vocabulary for Fiber Optics and Lightwave Communications, written by this author. Based on a draft prepared by this author, the National Communications System published Federal Standard FED-STD-1037, Glossary of Telecommunications Terms, in 1980 with no fiber optics tenns. In 1981, the first edition of this dictionary was published under the title Fiber Optics and Lightwave Communications Standard Dictionary. In 1982, the then National Bureau of Standards, now the National Institute of Standards and Technology, published NBS Handbook 140, Optical Waveguide Communications Glossary, which was also published by the General Services Admin­ istration as PB82-166257 under the same title. Also in 1982, Dynamic Systems, Inc. , Fiberoptic Sensor Technology Handbook, co-authored and edited by published the this author, with an extensive Fiberoptic Sensors Glossary. In 1989, the handbook w...

  19. Fiber Optic Microphone

    Science.gov (United States)

    Cho, Y. C.; George, Thomas; Norvig, Peter (Technical Monitor)

    1999-01-01

    Research into advanced pressure sensors using fiber-optic technology is aimed at developing compact size microphones. Fiber optic sensors are inherently immune to electromagnetic noise, and are very sensitive, light weight, and highly flexible. In FY 98, NASA researchers successfully designed and assembled a prototype fiber-optic microphone. The sensing technique employed was fiber optic Fabry-Perot interferometry. The sensing head is composed of an optical fiber terminated in a miniature ferrule with a thin, silicon-microfabricated diaphragm mounted on it. The optical fiber is a single mode fiber with a core diameter of 8 micron, with the cleaved end positioned 50 micron from the diaphragm surface. The diaphragm is made up of a 0.2 micron thick silicon nitride membrane whose inner surface is metallized with layers of 30 nm titanium, 30 nm platinum, and 0.2 micron gold for efficient reflection. The active sensing area is approximately 1.5 mm in diameter. The measured differential pressure tolerance of this diaphragm is more than 1 bar, yielding a dynamic range of more than 100 dB.

  20. Polymer optical fiber fuse

    CERN Document Server

    Mizuno, Yosuke; Tanaka, Hiroki; Nakamura, Kentaro

    2013-01-01

    Although high-transmission-capacity optical fibers are in demand, the problem of the fiber fuse phenomenon needs to be resolved to prevent the destruction of fibers. As polymer optical fibers become more prevalent, clarifying their fuse properties has become important. Here, we experimentally demonstrate a fuse propagation velocity of 21.9 mm/s, which is 1 to 2 orders of magnitude slower than that in standard silica fibers. The achieved threshold power density and proportionality constant between the propagation velocity and the power density are respectively 1/186 of and 16.8 times the values for silica fibers. An oscillatory continuous curve instead of periodic voids is formed after the passage of the fuse. An easy fuse termination method is presented herein, along with its potential plasma applications.

  1. 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.

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    Jiangbing Du

    2015-04-01

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

  4. Aircraft fiber optic structural health monitoring

    Science.gov (United States)

    Mrad, Nezih

    2012-06-01

    Structural Health Monitoring (SHM) is a sought after concept that is expected to advance military maintenance programs, increase platform operational safety and reduce its life cycle cost. Such concept is further considered to constitute a major building block of any Integrated Health Management (IHM) capability. Since 65% to 80% of military assets' Life Cycle Cost (LCC) is devoted to operations and support (O&S), the aerospace industry and military sectors continue to look for opportunities to exploit SHM systems, capability and tools. Over the past several years, countless SHM concepts and technologies have emerged. Among those, fiber optic based systems were identified of significant potential. This paper introduces the elements of an SHM system and investigates key issues impeding the commercial implementation of fiber optic based SHM capability. In particular, this paper presents an experimental study of short gauge, intrinsic, spectrometric-based in-fiber Bragg grating sensors, for potential use as a component of an SHM system. Fiber optic Bragg grating sensors are evaluated against resistance strain gauges for strain monitoring, sensitivity, accuracy, reliability, and fatigue durability. Strain field disturbance is also investigated by "embedding" the sensors under a photoelastic coating in order to illustrate sensor intrusiveness in an embedded configuration.

  5. On the Effects of the Lateral Strains on the Fiber Bragg Grating Response

    Directory of Open Access Journals (Sweden)

    Marco Lai

    2013-02-01

    Full Text Available In this paper, a combined experimental-numerical based work was undertaken to investigate the Bragg wavelength shift response of an embedded FBG sensor when subjected to different conditions of multi-axial loading (deformation. The following cases are examined: (a when an isotropic host material with no constrains on planes normal to the embedded sensor’s axis is biaxially loaded, (b when the same isotropic host material is subjected to hydrostatic pressure and (c when the hydrostatically loaded host material is an anisotropic one, as in the case of a composite material, where the optical fiber is embedded along the reinforcing fibers. The comparison of the experimental results and the finite element simulations shows that, when the axial strain on the FBG sensor is the dominant component, the standard wavelength-shift strain relation can be used even if large lateral strains apply on the sensor. However when this is not the case, large errors may be introduced in the conversion of the wavelength to axial strains on the fiber. This situation arises when the FBG is placed parallel to high modulus reinforcing fibers of a polymer composite.

  6. On the Effects of the Lateral Strains on the Fiber Bragg Grating Response

    Science.gov (United States)

    Lai, Marco; Karalekas, Dimitris; Botsis, John

    2013-01-01

    In this paper, a combined experimental-numerical based work was undertaken to investigate the Bragg wavelength shift response of an embedded FBG sensor when subjected to different conditions of multi-axial loading (deformation). The following cases are examined: (a) when an isotropic host material with no constrains on planes normal to the embedded sensor's axis is biaxially loaded, (b) when the same isotropic host material is subjected to hydrostatic pressure and (c) when the hydrostatically loaded host material is an anisotropic one, as in the case of a composite material, where the optical fiber is embedded along the reinforcing fibers. The comparison of the experimental results and the finite element simulations shows that, when the axial strain on the FBG sensor is the dominant component, the standard wavelength-shift strain relation can be used even if large lateral strains apply on the sensor. However when this is not the case, large errors may be introduced in the conversion of the wavelength to axial strains on the fiber. This situation arises when the FBG is placed parallel to high modulus reinforcing fibers of a polymer composite. PMID:23429580

  7. 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.

  8. Fiber Optics: No Illusion.

    Science.gov (United States)

    American School and University, 1983

    1983-01-01

    A campus computer center at Hofstra University (New York) that holds 70 terminals for student use was first a gymnasium, then a language laboratory. Strands of fiber optics are used for the necessary wiring. (MLF)

  9. Fiber optic detector

    Energy Technology Data Exchange (ETDEWEB)

    Partin, J.K.; Ward, T.E.; Grey, A.E.

    1990-12-31

    This invention is comprised of a portable fiber optic detector that senses the presence of specific target chemicals by exchanging the target chemical for a fluorescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

  10. Fiber optics welder

    Science.gov (United States)

    Higgins, R.W.; Robichaud, R.E.

    A system is described for welding fiber optic waveguides together. The ends of the two fibers to be joined together are accurately, collinearly aligned in a vertical orientation and subjected to a controlled, diffuse arc to effect welding and thermal conditioning. A front-surfaced mirror mounted at a 45/sup 0/ angle to the optical axis of a stereomicroscope mounted for viewing the junction of the ends provides two orthogonal views of the interface during the alignment operation.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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)

  18. 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.

  19. 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.

  20. Fabrication of an IR hollow-core Bragg fiber based on chalcogenide glass extrusion

    Science.gov (United States)

    Zhu, Minming; Wang, Xunsi; Pan, Zhanghao; Cheng, Ci; Zhu, Qingde; Jiang, Chen; Nie, Qiuhua; Zhang, Peiqing; Wu, Yuehao; Dai, Shixun; Xu, Tiefeng; Tao, Guangming; Zhang, Xianghua

    2015-05-01

    The theoretical analysis and experimental preparation of a hollow-core Bragg fiber based on chalcogenide glasses are demonstrated. The fiber has potential applications in bio-sensing and IR energy transmission. Two chalcogenide glasses with, respectively, high and low refractive indexes are investigated in detail for the fabrication of hollow-core Bragg fibers. The most appropriate structure is selected; this structure is composed of four concentric rings and a center air hole . Its band gap for the Bragg fiber is analyzed by the plane wave method. The chalcogenide glasses Ge15Sb20S58.5I13 and Ge15Sb10Se75 are chosen to extrude the robust multi-material glass preform with a specialized punch and glass container. The glass preform is simultaneously protected with a polyetherimide polymer. The hollow-core Bragg fibers are finally obtained after glass preform extrusion, fiber preform fabrication, and fiber drawing. Results showed that the fiber has a transparency window from 2.5 to 14 μm, including a low-loss transmission window from 10.5 to 12 μm. The location of this low-loss transmission window matches the predicted photonic band gap in the simulation.

  1. Nonlinear effects in optical fibers

    CERN Document Server

    Ferreira, Mario F

    2011-01-01

    Cutting-edge coverage of nonlinear phenomena occurring inside optical fibers Nonlinear fiber optics is a specialized part of fiber optics dealing with optical nonlinearities and their applications. As fiber-optic communication systems have become more advanced and complex, the nonlinear effects in optical fibers have increased in importance, as they adversely affect system performance. Paradoxically, the same nonlinear phenomena also offer the promise of addressing the bandwidth bottleneck for signal processing for future ultra-high speed optical networks. Nonlinear Effects in Optical Fiber

  2. 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.

  3. 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

  4. Distributed delay-line interferometer based on a Bragg grating in transmission mode

    CERN Document Server

    Preciado, Miguel A; Shu, Xuewen; Sugden, Kate

    2016-01-01

    A novel approach for a delay line interferometer (DLI) based purely on forward Bragg scattering is proposed. We have numerically and experimentally demonstrated that a Bragg grating can deliver the functionality of a DLI in its transmission mode along a single common interfering optical path, instead of the conventional DLI implementation with two interfering optical paths. As a proof of concept, a fiber Bragg grating has been designed and fabricated, showing the desired functionality in the transmission mode of the Bragg grating. The proposed "Bragg-DLI" approach is applicable to any kind of Bragg grating technology, such as volume Bragg gratings, dielectric mirrors, silicon photonics, and other optical waveguide based Bragg structures.

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

    Directory of Open Access Journals (Sweden)

    Umesh Sampath

    2015-07-01

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

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

    Science.gov (United States)

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

    2015-07-27

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

  7. 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.

  8. 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.

  9. Electrospun amplified fiber optics.

    Science.gov (United States)

    Morello, Giovanni; Camposeo, Andrea; Moffa, Maria; Pisignano, Dario

    2015-03-11

    All-optical signal processing is the focus of much research aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for efficient signal transmission. However, the complex fabrication methods involving high-temperature processes performed in a highly pure environment slow the fabrication process and make amplified components expensive with respect to an ideal, high-throughput, room temperature production. Here, we report on near-infrared polymer fiber amplifiers working over a band of ∼20 nm. The fibers are cheap, spun with a process entirely carried out at room temperature, and shown to have amplified spontaneous emission with good gain coefficients and low levels of optical losses (a few cm(-1)). The amplification process is favored by high fiber quality and low self-absorption. The found performance metrics appear to be suitable for short-distance operations, and the large variety of commercially available doping dyes might allow for effective multiwavelength operations by electrospun amplified fiber optics.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. Signal processing method based on group delay calculation for distributed Bragg wavelength shift in optical frequency domain reflectometry.

    Science.gov (United States)

    Wada, Daichi; Igawa, Hirotaka; Murayama, Hideaki; Kasai, Tokio

    2014-03-24

    A signal processing method based on group delay calculations is introduced for distributed measurements of long-length fiber Bragg gratings (FBGs) based on optical frequency domain reflectometry (OFDR). Bragg wavelength shifts in interfered signals of OFDR are regarded as group delay. By calculating group delay, the distribution of Bragg wavelength shifts is obtained with high computational efficiency. We introduce weighted averaging process for noise reduction. This method required only 3.5% of signal processing time which was necessary for conventional equivalent signal processing based on short-time Fourier transform. The method also showed high sensitivity to experimental signals where non-uniform strain distributions existed in a long-length FBG.

  16. 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.

  17. 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.

  18. 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.

  19. High speed, high-resolution fiber Bragg grating sensing system for monitoring of weigh-in-motion devices

    Science.gov (United States)

    Tosi, D.; Olivero, M.; Perrone, G.; Vallan, A.

    2011-05-01

    We present a fast high-resolution fiber Bragg grating sensing system for weigh-in-motion (WIM) application. The proposed system makes use of standard telecom photonics components operating at high speed and with insufficient resolution; then, using signal processing we artificially improve the accuracy of the system down to 1 μɛ. This way, the proposed architecture overcomes the state of the art of optical systems for WIM, which cannot cope with both high resolution and high frequency requirements. The developed system has been applied to a prototype weigh-in-motion device, which consists of a road speed bump. Structural deformations of the bump when perturbed by a thin-footmark load are well reproduced. Using multiple Bragg grating sensors, it is possible to unambiguously determine position and weight of a moving load on the bump with accuracy of 0.2 - 1.2 kg.

  20. Finite-difference modeling of Bragg fibers with ultrathin cladding layers via adaptive coordinate transformation

    DEFF Research Database (Denmark)

    Shyroki, Dzmitry; Lægsgaard, Jesper; Bang, Ole

    As an alternative to the finite-element analysis or subgridding, coordinate transformation is used to “stretch” the fine-structured cladding of a Bragg fiber, and then the fullvector, equidistant-grid finite-difference computations of the modal structure are performed.......As an alternative to the finite-element analysis or subgridding, coordinate transformation is used to “stretch” the fine-structured cladding of a Bragg fiber, and then the fullvector, equidistant-grid finite-difference computations of the modal structure are performed....

  1. 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.

  2. Finite-difference modeling of Bragg fibers with ultrathin cladding layers via adaptive coordinate transformation

    DEFF Research Database (Denmark)

    Shyroki, Dzmitry; Lægsgaard, Jesper; Bang, Ole;

    As an alternative to the finite-element analysis or subgridding, coordinate transformation is used to “stretch” the fine-structured cladding of a Bragg fiber, and then the fullvector, equidistant-grid finite-difference computations of the modal structure are performed.......As an alternative to the finite-element analysis or subgridding, coordinate transformation is used to “stretch” the fine-structured cladding of a Bragg fiber, and then the fullvector, equidistant-grid finite-difference computations of the modal structure are performed....

  3. 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.

  4. 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.

  5. Fiber optic sensing and imaging

    CERN Document Server

    2013-01-01

    This book is designed to highlight the basic principles of fiber optic imaging and sensing devices. The editor has organized the book to provide the reader with a solid foundation in fiber optic imaging and sensing devices. It begins with an introductory chapter that starts from Maxwell’s equations and ends with the derivation of the basic optical fiber characteristic equations and solutions (i.e. fiber modes). Chapter 2 reviews most common fiber optic interferometric devices and Chapter 3 discusses the basics of fiber optic imagers with emphasis on fiber optic confocal microscope. The fiber optic interferometric sensors are discussed in detail in chapter 4 and 5. Chapter 6 covers optical coherence tomography and goes into the details of signal processing and systems level approach of the real-time OCT implementation. Also useful forms of device characteristic equations are provided so that this book can be used as a reference for scientists and engineers in the optics and related fields.

  6. Polymer Optical Fibre Bragg Grating Humidity Sensor at 100ºC

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Fasano, Andrea; Markos, Christos

    2016-01-01

    We have demonstrated a polymer optical fibre Bragg grating humidity sensor that can be operated up to 100ºC. The sensor has been fabricated from a polycarbonate (PC) microstructured polymer optical fibre Bragg grating (mPOFBG). PC mPOFBG gave a relative humidity (RH) sensitivity of 6.95±0.83 pm...

  7. Fluoride glass fiber optics

    CERN Document Server

    Aggarwal, Ishwar D

    1991-01-01

    Fluoride Glass Fiber Optics reviews the fundamental aspects of fluoride glasses. This book is divided into nine chapters. Chapter 1 discusses the wide range of fluoride glasses with an emphasis on fluorozirconate-based compositions. The structure of simple fluoride systems, such as BaF2 binary glass is elaborated in Chapter 2. The third chapter covers the intrinsic transparency of fluoride glasses from the UV to the IR, with particular emphasis on the multiphonon edge and electronic edge. The next three chapters are devoted to ultra-low loss optical fibers, reviewing methods for purifying and

  8. Optical fiber rotation sensing

    CERN Document Server

    Burns, William K; Kelley, Paul

    1993-01-01

    Optical Fiber Rotation Sensing is the first book devoted to Interferometric Fiber Optic Gyros (IFOG). This book provides a complete overview of IFOGs, beginning with a historical review of IFOG development and including a fundamental exposition of basic principles, a discussion of devices and components, and concluding with industry reports on state-of-the-art activity. With several chapters contributed by principal developers of this solid-state device, the result is an authoritative work which will serve as the resource for researchers, students, and users of IFOGs.* * State-of-t

  9. Optical fiber telecommunications IIIb

    CERN Document Server

    Koch, Thomas L

    2012-01-01

    Updated to include the latest information on light wave technology, Optical Fiber Telecommunication III, Volumes A & B are invaluable for scientists, students, and engineers in the modern telecommunications industry. This two-volume set includes the most current research available in optical fiber telecommunications, light wave technology, and photonics/optoelectronics. The authors cover important background concepts such as SONET, coding device technology, andWOM components as well as projecting the trends in telecommunications for the 21st century.Key Features* One of the hottest subjects of

  10. 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

  11. Roof Polishing of Optical Fibers

    Science.gov (United States)

    Dholakia, A. R.

    1985-01-01

    Bevealed tip gives optimum coupling efficiency. Abrasive tape used to grind tip of optical fiber. Grinding force depends on stiffness of optical fiber. "Roof" shape on end of optical glass fiber increases efficiency which couples laser light. End surface angle of 65 degrees with perpendicular required for optimum coupling. Since fiber and tape are light in weight and compliant, ridge defect-free, and chipping on fiber edge totally eliminated.

  12. Optical fiber communications

    CERN Document Server

    Keiser, Gerd

    2008-01-01

    The fourth edition of this popular text and reference book presents the fundamental principles for understanding and applying optical fiber technology to sophisticated modern telecommunication systems. Optical-fiber-based telecommunication networks have become a major information-transmission-system, with high capacity links encircling the globe in both terrestrial and undersea installations. Numerous passive and active optical devices within these links perform complex transmission and networking functions in the optical domain, such as signal amplification, restoration, routing, and switching. Along with the need to understand the functions of these devices comes the necessity to measure both component and network performance, and to model and stimulate the complex behavior of reliable high-capacity networks.

  13. Applications of nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind

    2008-01-01

    * The only book describing applications of nonlinear fiber optics * Two new chapters on the latest developments: highly nonlinear fibers and quantum applications* Coverage of biomedical applications* Problems provided at the end of each chapterThe development of new highly nonlinear fibers - referred to as microstructured fibers, holey fibers and photonic crystal fibers - is the next generation technology for all-optical signal processing and biomedical applications. This new edition has been thoroughly updated to incorporate these key technology developments.The bo

  14. 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.

  15. Fabrication of Fiber Bragg Grating Coating with TiO2 Nanostructured Metal Oxide for Refractive Index Sensor

    Directory of Open Access Journals (Sweden)

    Shaymaa Riyadh Tahhan

    2017-01-01

    Full Text Available To increase the sensitivity of biosensor a new approach using an optical fiber Bragg grating (FBG coated with a suitable nanostructured metal oxide (NMO is proposed which is costly effective compared to other biosensors. Bragg grating was written on a D-shaped optical fiber by phase mask method using a 248 nm KrF excimer laser for a 5 min exposure time producing a grating with a period of 528 nm. Titanium dioxide (TiO2 nanostructured metal oxide was coated over the fiber for the purpose of increasing its sensing area. The etched D-shaped FBG was then coated with 312 nm thick TiO2 nanostructured layer to ensure propagating the radiation modes within the core. The final structure was used to sense deionized water and saline. The etched D-shaped FBG original sensitivity before coating to air-deionized water and to air-saline was 0.314 nm/riu and 0.142 nm/riu, respectively. After coating the sensitivity became 1.257 nm/riu for air-deionized water and 0.857 nm/riu for air-saline.

  16. 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.

  17. Ultra-large bandwidth hollow-core guiding in all-silica bragg fibers with nano-supports

    DEFF Research Database (Denmark)

    Vienne, Guillaume; Xu, Yong; Jakobsen, Christian;

    2004-01-01

    We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding...... in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m....

  18. Microstructured Optical Fiber Sensors Embedded in a Laminate Composite for Smart Material Applications

    Directory of Open Access Journals (Sweden)

    Hugo Thienpont

    2011-02-01

    Full Text Available Fiber Bragg gratings written in highly birefringent microstructured optical fiber with a dedicated design are embedded in a composite fiber-reinforced polymer. The Bragg peak wavelength shifts are measured under controlled axial and transversal strain and during thermal cycling of the composite sample. We obtain a sensitivity to transversal strain that exceeds values reported earlier in literature by one order of magnitude. Our results evidence the relevance of using microstructured optical fibers for structural integrity monitoring of composite material structures.

  19. 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.

  20. 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.

  1. 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.

  2. Field analysis of TE and TM modes in photonic crystal Bragg fibers by transmission matrix method

    Directory of Open Access Journals (Sweden)

    M Hosseini Farzad

    2010-03-01

    Full Text Available In this article, we considered the field analysis in photonic crystal Bragg fibers. We apply the method of transmission matrix to calculater the dispersion curves, the longitudinal wave number over wave number versus incident wavelength, and the field distributions of TE and TM modes in the Bragg fiber. Our analysis shows that the field of guided modes is confined in the core and can exist only in particular wavelength bands corresponding to the band-gap of the periodic structure of the clad. From another point of view, light confinement is due to Bragg reflection from high-and low-refractive index layers of the clad. Also, the diagram of average angular frequency with respect to average longitudinal wave number is plotted so that the band gap regions of the clad are clearly observed.

  3. Compact fiber optic accelerometer

    Institute of Scientific and Technical Information of China (English)

    Feng Peng; Jun Yang; Bing Wu; Yonggui Yuan; Xingliang Li; Ai Zhou; Libo Yuan

    2012-01-01

    A compact fiber optic accelerometer based on a Michelson interferometer is proposed and demonstrated.In the proposed system,the sensing element consists of two single-mode fibers glued together by epoxy,which then act as a simple supported beam.By demodulating the optical phase shift,the acceleration is determined as proportional to the force applied on the central position of the two single-mode fibers.This simple model is able to calculate the sensitivity and the resonant frequency of the compact accelerometer.The experimental results show that the sensitivity and the resonant frequency of the accelerometer are 0.42 rad/g and 600 Hz,respectively.

  4. Infrared Fiber Optic Sensors

    Science.gov (United States)

    1997-01-01

    Successive years of Small Business Innovation Research (SBIR) contracts from Langley Research Center to Sensiv Inc., a joint venture between Foster-Miller Inc. and Isorad, Ltd., assisted in the creation of remote fiber optic sensing systems. NASA's SBIR interest in infrared, fiber optic sensor technology was geared to monitoring the curing cycles of advanced composite materials. These funds helped in the fabrication of an infrared, fiber optic sensor to track the molecular vibrational characteristics of a composite part while it is being cured. Foster-Miller ingenuity allowed infrared transmitting optical fibers to combine with Fourier Transform Infrared spectroscopy to enable remote sensing. Sensiv probes operate in the mid-infrared range of the spectrum, although modifications to the instrument also permits its use in the near-infrared region. The Sensiv needle-probe is built to be placed in a liquid or powder and analyze the chemicals in the mixture. Other applications of the probe system include food processing control; combustion control in furnaces; and maintenance problem solving.

  5. Optical Fiber Protection

    Science.gov (United States)

    1999-01-01

    F&S Inc. developed and commercialized fiber optic and microelectromechanical systems- (MEMS) based instrumentation for harsh environments encountered in the aerospace industry. The NASA SBIR programs have provided F&S the funds and the technology to develop ruggedized coatings and coating techniques that are applied during the optical fiber draw process. The F&S optical fiber fabrication facility and developed coating methods enable F&S to manufacture specialty optical fiber with custom designed refractive index profiles and protective or active coatings. F&S has demonstrated sputtered coatings using metals and ceramics and combinations of each, and has also developed techniques to apply thin coatings of specialized polyimides formulated at NASA Langley Research Center. With these capabilities, F&S has produced cost-effective, reliable instrumentation and sensors capable of withstanding temperatures up to 800? C and continues building commercial sales with corporate partners and private funding. More recently, F&S has adapted the same sensing platforms to provide the rapid detection and identification of chemical and biological agents

  6. Damage evaluation and analysis of composite pressure vessels using fiber Bragg gratings to determine structural health

    Science.gov (United States)

    Ortyl, Nicholas E.

    2005-11-01

    The application of MEMS and nanotechnology (MNT) to the field of structural health monitoring (SHM) is a fairly recent development. The recent change in this focus for MNT has been driven by the need to expand the applications for much of the technologies that were developed in the late 1990s. In addition, many companies desire to expand beyond their target high volume market segments of automotive, wireless communications, and computer peripherals, since these market segments were not as lucrative as first predicted. Most of the aerospace structural health monitoring developmental activity has been sponsored by agencies of the U.S. Government, which serves to pace the examination of these newer technologies to some degree. With that said, efforts are underway by companies such as Acellent Technologies and Blue Road Research to explore various MNT structural health monitoring approaches. The MNT under test include embedded piezoelectric sensors, MEMS accelerometers, time domain region sensors, and topical and embedded single and multi-axis fiber optic Bragg grating sensors. The promise of MNT for the SHM market segment is very enticing. The many wireless communication developments and miniaturization developments of the past five years is very attractive to the SHM community, especially those that are able to reduce the cost and complexity of integration. The main challenge for the community is one of selective integration. That is, certain pieces may be appropriate for SHM systems and certain pieces may not be. The better companies will chose wisely and put forth an approach that can be seamlessly integrated into the larger structure. For over a decade, Blue Road Research has been developing technologies aimed at structural health monitoring of both composite and non-composite parts, through the use of single and multiaxis fiber optic Bragg grating sensors. These sensors are 80 to 120 microns in diameter making them smaller than the diameter of a human hair

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-01

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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Cure monitoring of epoxy resin by using fiber bragg grating sensor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin Hyuk [KEPCO, Naju (Korea, Republic of); Kim, Dae Hyun [Dept. of Mechanical and Automotive Engineering, Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2016-06-15

    In several industrial fields, epoxy resin is widely used as an adhesive for co-curing and manufacturing various structures. Controlling the manufacturing process is required for ensuring robust bonding performance and the stability of the structures. A fiber optic sensor is suitable for the cure monitoring of epoxy resin owing to the thready shape of the sensor. In this paper, a fiber Bragg grating (FBG) sensor was applied for the cure monitoring of epoxy resin. Based on the experimental results, it was demonstrated that the FBG sensor can monitor the status of epoxy resin curing by measuring the strain caused by volume shrinkage and considering the compensation of temperature. In addition, two types of epoxy resin were used for the cure-monitoring; moreover, when compared to each other, it was found that the two types of epoxy had different cure-processes in terms of the change of strain during the curing. Therefore, the study proved that the FBG sensor is very profitable for the cure-monitoring of epoxy resin.

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

    CERN Document Server

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

    2014-01-01

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

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

    Science.gov (United States)

    Dennison, Christopher R.; Wild, Peter M.; Wilson, David R.; Cripton, Peter A.

    2008-08-01

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

  16. Dynamic Strain Sensing in a Long-Span Suspension Bridge Using Fiber Bragg Grating Sensors

    Science.gov (United States)

    Zhu, Yinian; Zhu, Yan-Jin; Balogun, Oluwaseyi; Zhu, Songye; Xu, You-Lin; Krishnaswamy, Sridhar

    2011-06-01

    Optical fiber sensors are ideal for monitoring continuous deterioration conditions of civil infrastructure, especially of long-span bridges. Typically, a network of sensors is used to measure the strains or low frequency vibrational response of the structure. In this work, we demonstrate dynamic spectral demodulation of fiber Bragg grating (FBG) sensor responses with a stabilized Michelson interferometer for monitoring mechanical strains in a model of long-span bridge. A series of experiments has been performed, including the measurements of the natural resonant modes of the model bridge, impact response of a bridge member and acoustic emissions in a fractured aluminum bar. The experimental results not only reveal that dynamic spectral demodulation of FBG strain responses at frequencies extending up to about 3.5 MHz is possible, but also suggest that the method may be suitable for monitoring high frequency mechanical strains in civil structures that result from cracking or impact loading, thus providing a tool for local detection of structural damage.

  17. Pasted type distributed two-dimensional fiber Bragg grating vibration sensor.

    Science.gov (United States)

    Li, Tianliang; Tan, Yuegang; Zhou, Zude; Wei, Qin

    2015-07-01

    A pasted type distributed two-dimensional fiber Bragg grating (FBG) vibration sensor has been proposed and studied in this paper. The optical fiber is directly considered as an elastomer. The two-dimensional vibration can be separated by subtraction/addition of two FBGs' center wavelength shift. The principle of the sensor as well as numerical simulation and experimental analyses are presented. Experimental results show that the resonant frequencies of the sensor x/y main vibration direction are separately 1300/20.51 Hz, which are consistent with the numerical simulation analysis result. The flat frequency range resides in 10-750 Hz and 3-12 Hz, respectively; dynamic range is 28.63 dB; in the x main vibration direction, the sensor's sensitivity is 32.84 pm/g, with linearity 3.91% in the range of 10-60 m/s(2), while in the y main vibration direction, the sensor's sensitivity is 451.3 pm/g, with linearity 1.92% in the range of 1.5-8 m/s(2). The cross sensitivity is 3.91%. Benefitting from the two dimensional sensing properties, it can be used in distributed two-dimensional vibration measurement.

  18. Three-axial Fiber Bragg Grating Strain Sensor for Volcano Monitoring

    Science.gov (United States)

    Giacomelli, Umberto; Beverini, Nicolò; Carbone, Daniele; Carelli, Giorgio; Francesconi, Francesco; Gambino, Salvatore; Maccioni, Enrico; Morganti, Mauro; Orazi, Massimo; Peluso, Rosario; Sorrentino, Fiodor

    2017-04-01

    Fiber optic and FBGs sensors have attained a large diffusion in the last years as cost-effective monitoring and diagnostic devices in civil engineering. However, in spite of their potential impact, these instruments have found very limited application in geophysics. In order to study earthquakes and volcanoes, the measurement of crustal deformation is of crucial importance. Stress and strain behaviour is among the best indicators of changes in the activity of volcanoes .. Deep bore-hole dilatometers and strainmeters have been employed for volcano monitoring. These instruments are very sensitive and reliable, but are not cost-effective and their installation requires a large effort. Fiber optic based devices offer low cost, small size, wide frequency band, easier deployment and even the possibility of creating a local network with several sensors linked in an array. We present the realization, installation and first results of a shallow-borehole (8,5 meters depth) three-axial Fiber Bragg Grating (FBG) strain sensor prototype. This sensor has been developed in the framework of the MED-SUV project and installed on Etna volcano, in the facilities of the Serra La Nave astrophysical observatory. The installation siteis about 7 Km South-West of the summit craters, at an elevation of about 1740 m. The main goal of our work is the realization of a three-axial device having a high resolution and accuracy in static and dynamic strain measurements, with special attention to the trade-off among resolution, cost and power consumption. The sensor structure and its read-out system are innovative and offer practical advantages in comparison with traditional strain meters. Here we present data collected during the first five months of operation. In particular, the very clear signals recorded in the occurrence of the Central Italy seismic event of October 30th demonstrate the performances of our device.

  19. Simulating increased Lamb wave detection sensitivity of surface bonded fiber Bragg grating

    Science.gov (United States)

    Wee, J.; Hackney, D. A.; Bradford, P. D.; Peters, K. J.

    2017-04-01

    Fiber Bragg grating (FBG) sensors are excellent transducers for collecting ultrasonic wave signals for structural health monitoring (SHM). Typically, FBG sensors are directly bonded to the surface of a structure to detect signals. Unfortunately, demodulating relevant information from the collected signal demands a high signal-to-noise ratio because the structural ultrasonic waves have low amplitudes. Our previous experimental work demonstrated that the optical fiber could be bonded at a distance away from the FBG location, referred to here as remote bonding. This remote bonding technique increased the output signal amplitude compared to the direct bonding case, however the mechanism causing the increase was not explored. In this work, we simulate the previous experimental work through transient analysis based on the finite element method, and the output FBG response is calculated through the transfer matrix method. The model is first constructed without an adhesive to assume an ideal bonding condition, investigating the difference in excitation signal coherence along the FBG length between the two bonding configurations. A second model is constructed with an adhesive to investigate the effect of the presence of the adhesive around the FBG. The results demonstrate that the amplitude increase is originated not from the excitation signal coherence, but from the shear lag effect which causes immature signal amplitude development in the direct bonding case compared to the remote bonding case. The results also indicate that depending on the adhesive properties the surface-bonded optical fiber manifests varying resonant frequency, therefore resulting in a peak amplitude response when the input excitation frequency is matched. This work provides beneficial reference for selecting adhesive and calibrating sensing system for maximum ultrasonic detection sensitivity using the FBG sensor.

  20. 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

  1. 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.

  2. Fiber Optics and Library Technology.

    Science.gov (United States)

    Koenig, Michael

    1984-01-01

    This article examines fiber optic technology, explains some of the key terminology, and speculates about the way fiber optics will change our world. Applications of fiber optics to library systems in three major areas--linkage of a number of mainframe computers, local area networks, and main trunk communications--are highlighted. (EJS)

  3. Buying Fiber-Optic Networks.

    Science.gov (United States)

    Fickes, Michael

    2003-01-01

    Describes consortia formed by college and university administrators to buy, manage, and maintain their own fiber-optic networks with the goals of cutting costs of leasing fiber-optic cable and planning for the future. Growth capacity is the real advantage of owning fiber-optic systems. (SLD)

  4. Aerogel-clad optical fiber

    Science.gov (United States)

    Sprehn, Gregory A.; Hrubesh, Lawrence W.; Poco, John F.; Sandler, Pamela H.

    1997-01-01

    An optical fiber is surrounded by an aerogel cladding. For a low density aerogel, the index of refraction of the aerogel is close to that of air, which provides a high numerical aperture to the optical fiber. Due to the high numerical aperture, the aerogel clad optical fiber has improved light collection efficiency.

  5. Fiber Optic Thermal Health Monitoring of Aerospace Structures and Materials

    Science.gov (United States)

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

    2009-01-01

    A new technique is presented for thermographic detection of flaws in materials and structures by performing temperature measurements with fiber Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of structures with subsurface defects or thickness variations. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. The data obtained from grating sensors were further analyzed with thermal modeling to reveal particular characteristics of the interested areas. These results were found to be consistent with those from conventional thermography techniques. Limitations of the technique were investigated using both experimental and numerical simulation techniques. Methods for performing in-situ structural health monitoring are discussed.

  6. 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...

  7. 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

  8. 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

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

    NARCIS (Netherlands)

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

    2006-01-01

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

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

    NARCIS (Netherlands)

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

    2006-01-01

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

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

    NARCIS (Netherlands)

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

    2006-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  13. 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.

  14. 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.

  15. Low-coherence interferometric measurements of optical losses in autoclave cured composite samples with embedded optical fibers

    Science.gov (United States)

    Di Sante, Raffaella; Bastianini, Filippo; Donati, Lorenzo

    2013-05-01

    In this work a high-performance optical low-coherence reflectometer (OLCR) has been used to estimate the optical losses in optical fibers and fiber Bragg grating sensors embedded into CFRP material samples. An ASE tunable narrowband light source coupled to a Michelson interferometer allowed the high spatial resolution localization of both the concentrated and the distributed loss for different fiber coatings and type. In particular, acrylate- and polyimidecoated fibers and bend-insensitive fibers were tested. By using the OLCR it was possible to locate and identify the sources of optical loss introduced by the CFRP manufacturing process, therefore obtaining useful information on the efficiency of the embedding process.

  16. Nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind

    2012-01-01

    Since the 4e appeared, a fast evolution of the field has occurred. The 5e of this classic work provides an up-to-date account of the nonlinear phenomena occurring inside optical fibers, the basis of all our telecommunications infastructure as well as being used in the medical field. Reflecting the big developments in research, this new edition includes major new content: slow light effects, which offers a reduction in noise and power consumption and more ordered network traffic-stimulated Brillouin scattering; vectorial treatment of highly nonlinear fibers; and a brand new chapter o

  17. [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

  18. Optical Filters Utilizing Ion Implanted Bragg Gratings in SOI Waveguides

    Directory of Open Access Journals (Sweden)

    M. P. Bulk

    2008-01-01

    Full Text Available The refractive index modulation associated with the implantation of oxygen or silicon into waveguides formed in silicon-on-insulator (SOI has been investigated to determine the feasibility of producing planar, implantation induced Bragg grating optical filters. A two-dimensional coupled mode theory-based simulation suggests that relatively short grating lengths, on the order of a thousand microns, can exhibit sufficient wavelength suppression, of >10 dB, using the implantation technique. Fabricated planar implanted slab-guided SOI waveguides demonstrated an extinction of −10 dB for TE modes and −6 dB for TM modes for the case of oxygen implantation. Extinctions of −5 dB and −2 dB have been demonstrated with silicon implantation.

  19. Flexural performance experimental study on steel beam strengthened with prestressed CFRP plate based on optical fiber bragg grating%基于光纤光栅的预应力碳纤维板加固钢梁抗弯性能试验研究

    Institute of Scientific and Technical Information of China (English)

    邓朗妮; 梁静远; 廖羚; 彭来; 赵思敏

    2015-01-01

    结合碳纤维增强复合材料(CFRP)的高强特性及光纤光栅(OFBG)的感知特性,研制开发CFRP-OFBG智能复合板,通过试验验证其应变传感性能。完成预应力CFRP-OFBG板加固钢梁静载试验,监测钢梁的应变和屈服破坏过程,研究预应力CFRP-OFBG智能碳纤维板加固钢梁的抗弯性能。结果表明:预应力CFRP-OFBG智能碳纤维板是一种集受力和传感于一体的新型土木工程材料,克服了光纤光栅埋设的工艺问题,并且能有效提高加固钢梁的抗弯性能,具有良好的推广价值和应用前景。%By combining the high strength of carbon fiber reinforced polymer (CFRP) with the sensing characteristics of optical bragg grating (OFBG), a smart CFRP-OFBG composite laminate is developed. Its mechanical properties and sensing characteristics are studied by test. The steel beams strengthened with prestressed CFRP-OFBG plates were tested to monitor the process of yield damage and strain while studying the flexural performance at the same time. The experimental results show that the prestressed CFRP-OFBG plate is a new material combined force and contingency perception; it can solve the problem of technology of embedded optical fiber Bragg grating and effectively improve the flexural capacity in the meanwhile, has good popularized value and application prospects.

  20. Surface plasmon resonance sensor interrogation with a double-clad fiber coupler and cladding modes excited by a tilted fiber Bragg grating.

    Science.gov (United States)

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

    2013-11-15

    We present a novel optical fiber surface plasmon resonance (SPR) sensor scheme using reflected guided cladding modes captured by a double-clad fiber coupler and excited in a gold-coated fiber with a tilted Bragg grating. This new interrogation approach, based on the reflection spectrum, provides an improvement in the operating range of the device over previous techniques. The device allows detection of SPR in the reflected guided cladding modes and also in the transmitted spectrum, allowing comparison with standard techniques. The sensor has a large operating range from 1.335 to 1.432 RIU, and a sensitivity of 510.5 nm/RIU. The device shows strong dependence on the polarization state of the guided core mode which can be used to turn the SPR on or off.

  1. 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.

  2. Enabling technologies for fiber optic sensing

    Science.gov (United States)

    Ibrahim, Selwan K.; Farnan, Martin; Karabacak, Devrez M.; Singer, Johannes M.

    2016-04-01

    In order for fiber optic sensors to compete with electrical sensors, several critical parameters need to be addressed such as performance, cost, size, reliability, etc. Relying on technologies developed in different industrial sectors helps to achieve this goal in a more efficient and cost effective way. FAZ Technology has developed a tunable laser based optical interrogator based on technologies developed in the telecommunication sector and optical transducer/sensors based on components sourced from the automotive market. Combining Fiber Bragg Grating (FBG) sensing technology with the above, high speed, high precision, reliable quasi distributed optical sensing systems for temperature, pressure, acoustics, acceleration, etc. has been developed. Careful design needs to be considered to filter out any sources of measurement drifts/errors due to different effects e.g. polarization and birefringence, coating imperfections, sensor packaging etc. Also to achieve high speed and high performance optical sensing systems, combining and synchronizing multiple optical interrogators similar to what has been used with computer/processors to deliver super computing power is an attractive solution. This path can be achieved by using photonic integrated circuit (PIC) technology which opens the doors to scaling up and delivering powerful optical sensing systems in an efficient and cost effective way.

  3. 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.

  4. Optical fiber synaptic sensor

    Science.gov (United States)

    Pisarchik, A. N.; Jaimes-Reátegui, R.; Sevilla-Escoboza, R.; García-Lopez, J. H.; Kazantsev, V. B.

    2011-06-01

    Understanding neuron connections is a great challenge, which is needed to solve many important problems in neurobiology and neuroengineering for recreation of brain functions and efficient biorobotics. In particular, a design of an optical synapse capable to communicate with neuron spike sequences would be crucial to improve the functionality of neuromimmetic networks. In this work we propose an optical synaptic sensor based on an erbium-doped fiber laser driven by a FitzHung-Nagumo electronic neuron, to connect with another electronic neuron. Two possible optical synaptic configurations are analyzed for optoelectronic coupling between neurons: laser cavity loss modulation and pump laser modulation. The control parameters of the proposed optical synapse provide additional degrees of flexibility to the neuron connection traditionally controlled only by coupling strengths in artificial networks.

  5. Simultaneous measurement of strain and temperature using a Fabry–Perot interferometer consisting of Bragg gratings in polarization-maintaining fiber and current-modulated laser diodes

    Science.gov (United States)

    Wada, Atsushi; Tanaka, Satoshi; Takahashi, Nobuaki

    2017-03-01

    A fast and high-resolution simultaneous measurement of strain and temperature using an optical fiber sensor is presented. Temperature and strain can be measured simultaneously by using two types of reflection spectra of a Fabry–Perot interferometer consisting of fiber Bragg gratings in a polarization-maintaining fiber (PM-FBG-FPI). The fine structure of a reflection spectrum of the PM-FBG-FPI enables the high-resolution detection of wavelength shifts. We present a fast interrogation method with current modulation of a laser diode for PM-FBG-FPI sensors. The resulting fast measurement is demonstrated experimentally.

  6. Fiber optic geophysical sensors

    Science.gov (United States)

    Homuth, Emil F.

    1991-01-01

    A fiber optic geophysical sensor in which laser light is passed through a sensor interferometer in contact with a geophysical event, and a reference interferometer not in contact with the geophysical event but in the same general environment as the sensor interferometer. In one embodiment, a single tunable laser provides the laser light. In another embodiment, separate tunable lasers are used for the sensor and reference interferometers. The invention can find such uses as monitoring for earthquakes, and the weighing of objects.

  7. 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.

  8. 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.

  9. MEMS Bragg grating force sensor

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  10. 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.

  11. Shedding Light on Fiber Optics.

    Science.gov (United States)

    Bunch, Robert M.

    1994-01-01

    Explains the principles of fiber optics as a medium for light-wave communication. Current uses of fiber systems on college campuses include voice, video, and local area network applications. A group of seven school districts in Minnesota are linked via fiber-optic cables. Other uses are discussed. (MLF)

  12. Optical fibers for FTTH application

    Science.gov (United States)

    Guzowski, Bartlomiej; Tosik, Grzegorz; Lisik, Zbigniew; Bedyk, Michal; Kubiak, Andrzej

    2013-07-01

    In this paper the specifics of FTTH (Fiber To The Home) networks in terms of requirements for optical fibers has been presented. Optical fiber samples used in FTTH applications acquired from the worldwide leading manufacturers were subjected to small diameter mandrel wraps tests. The detailed procedures of performed tests and the measurement results has been presented.

  13. Adaptive Integrated Optical Bragg Grating in Semiconductor Waveguide Suitable for Optical Signal Processing

    Science.gov (United States)

    Moniem, T. A.

    2016-05-01

    This article presents a methodology for an integrated Bragg grating using an alloy of GaAs, AlGaAs, and InGaAs with a controllable refractive index to obtain an adaptive Bragg grating suitable for many applications on optical processing and adaptive control systems, such as limitation and filtering. The refractive index of a Bragg grating is controlled by using an external electric field for controlling periodic modulation of the refractive index of the active waveguide region. The designed Bragg grating has refractive indices programmed by using that external electric field. This article presents two approaches for designing the controllable refractive indices active region of a Bragg grating. The first approach is based on the modification of a planar micro-strip structure of the iGaAs traveling wave as the active region, and the second is based on the modification of self-assembled InAs/GaAs quantum dots of an alloy from GaAs and InGaAs with a GaP traveling wave. The overall design and results are discussed through numerical simulation by using the finite-difference time-domain, plane wave expansion, and opto-wave simulation methods to confirm its operation and feasibility.

  14. All-Silica Hollow-Core Microstructured Bragg Fibers for Biosensor Application

    DEFF Research Database (Denmark)

    Passaro, Davide; Foroni, Matteo; Poli, Federica

    2008-01-01

    on the finite-element method. Since the DNA molecules necessary for the biosensor realization are in aqueous solution, it has been taken into account a microstructured fiber with water-filled holes. The dispersion curve and the confinement loss spectrum have been calculated in order to understand how a biofilm...... layer on the inner surface of the fiber holes can modify the fundamental mode properties. The numerical analysis results have successfully demonstrated the DNA bio-sensor feasibility in hollow-core Bragg fibers....

  15. Ultra-Weak Fiber Bragg Grating Sensing Network Coated with Sensitive Material for Multi-Parameter Measurements

    Directory of Open Access Journals (Sweden)

    Wei Bai

    2017-06-01

    Full Text Available A multi-parameter measurement system based on ultra-weak fiber Bragg grating (UFBG array with sensitive material was proposed and experimentally demonstrated. The UFBG array interrogation principle is time division multiplex technology with two semiconductor optical amplifiers as timing units. Experimental results showed that the performance of the proposed UFBG system is almost equal to that of traditional FBG, while the UFBG array system has obvious superiority with potential multiplexing ability for multi-point and multi-parameter measurement. The system experimented on a 144 UFBG array with the reflectivity of UFBG ~0.04% for the four target parameters: hydrogen, humidity, temperature and salinity. Moreover, a uniform solution was customized to divide the cross-sensitivity between temperature and other target parameters. It is expected that this scheme will be capable of handling thousands of multi-parameter sensors in a single fiber.

  16. Optical fiber crossbar switch

    Science.gov (United States)

    Kilcoyne, Michael K.; Beccue, Stephen M.; Brar, Berinder; Robinson, G.; Pedrotti, Kenneth D.; Haber, William A.

    1990-07-01

    Advances in high performance computers and signal processing systems have led to parallel system architectures. The main limitation in achieving the performance expected of these parallel systems has been the realization of an efficient means to interconnect many processors into a effective parallel system. Electronic interconnections have proved cumbersome, costly and ineffective. The Optical Fiber Crossbar Switch (OFCS) is a compact low power, multi-gigahertz bandwidth multi-channel switch which can be used in large scale computer and telecommunication applications. The switch operates in the optical domain using GaAs semiconductor lasers to transmit wideband multiple channel optical data over fiber optic cables. Recently, a 32 X 32 crossbar switching system was completed and demonstrated. Error free performance was obtained at a data bandwidth of 410 MBPS, using a silicon switch IC. The switch can be completely reconfigured in less than 50 nanoseconds under computer control. The fully populated OFCS has the capability to handle 12.8 gigabits per second (GBPS) of data while switching this data over 32 channels without the loss of a single bit during switching. GaAs IC technology has now progressed to the point that 16 X 16 GaAs based crossbar switch Ics are available which have increased the data bandwidth capability to 2.4 GBPS. The present optical interfaces are integrated GaAs transmitter drivers, GaAs lasers, and integrated GaAs optical receivers with data bandwidths exceeding 2.4 GBPS. A system using all Ill-V switching and optoelectronic components is presently under development for both NASA and DoD programs. The overall system is designed to operate at 1.3 GBPS. It is expected that these systems will find wide application in high capacity computing systems based on parallel microprocessor architecture which require high data bandwidth communication between processors. The OFCS will also have application in commercial optical telecommunication systems

  17. Study on embedding fiber Bragg grating sensor into the 3D printing structure for health monitoring

    Science.gov (United States)

    Li, Ruiya; Tan, Yuegang; Zhou, Zude; Fang, Liang; Chen, Yiyang

    2016-10-01

    3D printing technology is a rapidly developing manufacturing technology, which is known as a core technology in the third industrial revolution. With the continuous improvement of the application of 3D printing products, the health monitoring of the 3D printing structure is particularly important. Fiber Bragg grating (FBG) sensing technology is a new type of optical sensing technology with unique advantages comparing to traditional sensing technology, and it has great application prospects in structural health monitoring. In this paper, the FBG sensors embedded in the internal structure of the 3D printing were used to monitor the static and dynamic strain variation of 3D printing structure during loading process. The theoretical result and experimental result has good consistency and the characteristic frequency detected by FBG sensor is consistent with the testing results of traditional accelerator in the dynamic experiment. The results of this paper preliminary validate that FBG embedded in the 3D printing structure can effectively detecting the static and dynamic stain change of the 3D printing structure, which provide some guidance for the health monitoring of 3D printing structure.

  18. 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.

  19. Guiding Properties of Silica/Air Hollow-Core Bragg Fibers

    DEFF Research Database (Denmark)

    Foroni, Matteo; Passaro, Davide; Poli, Federica

    2008-01-01

    The guiding properties of realistic silica/air hollow-core Bragg fibers have been investigated by calculating the dispersion curves, the confinement loss spectrum and the field distribution of the guided modes through a full-vector modal solver based on the finite element method. In particular, t...... the different possible applications, the feasibility of a DNA bio-sensor based on a hollow-core Bragg fiber has been demonstrated.......The guiding properties of realistic silica/air hollow-core Bragg fibers have been investigated by calculating the dispersion curves, the confinement loss spectrum and the field distribution of the guided modes through a full-vector modal solver based on the finite element method. In particular......, the silica bridge influence on the fundamental mode has been analyzed, by comparing the properties of an ideal structure, without the silica nano-supports, and of two realistic fibers, with squared off and rounded air-holes. Simulation results have demonstrated the presence of anti-crossing points...

  20. Interferometric Fiber Optic Sensors

    Directory of Open Access Journals (Sweden)

    Hae Young Choi

    2012-02-01

    Full Text Available Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair.

  1. Interferometric fiber optic sensors.

    Science.gov (United States)

    Lee, Byeong Ha; Kim, Young Ho; Park, Kwan Seob; Eom, Joo Beom; Kim, Myoung Jin; Rho, Byung Sup; Choi, Hae Young

    2012-01-01

    Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG) is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair.

  2. 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

  3. Optical Electronic Bragg Reflection Sensor System with Hydrodynamic Flow Applications

    Science.gov (United States)

    Lyons, D. R.

    2003-01-01

    This project, as described in the following report, involved design and fabrication of fiber optic sensors for the detection and measurement of dynamic fluid density variations. These devices are created using UV (ultraviolet) ablation and generally modified transverse holographic fiber grating techniques. The resulting phase gratings created on or immediately underneath the flat portion of D-shaped optical waveguides are characterized as evanescent field sensing devices. The primary applications include the sensor portion of a real-time localized or distributed measurement system for hydrodynamic flow, fluid density measurements, and phase change phenomena. Several design modifications were implemented in an attempt to accomplish the tasks specified in our original proposal. In addition, we have established key collaborative relationships with numerous people and institutions.

  4. 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.

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

    Science.gov (United States)

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

    2005-05-01

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

  6. Fiber-Optic Sensor Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Constructs and evaluates fiber-optic sensors for a variety of measurands. These measurands include acoustic, pressure, magnetic, and electric field as well...

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Discourse on the Characterization of Waveguide Distributed Bragg Reflectors for Application to Nonlinear Optics

    Science.gov (United States)

    Grieco, Andrew Lewis

    Precise characterization of waveguide parameters is necessary for the successful design of nonlinear photonic devices. This dissertation contains a description of methods for the experimental characterization of distributed Bragg reflectors for use in nonlinear optics and other applications. The general coupled-mode theory of Bragg reflection arising from a periodic dielectric perturbation is developed from Maxwell's equations. This theory is then applied to develop a method of characterizing the fundamental parameters that describe Bragg reflection by comparing the spectral response of Bragg reflector resonators. This method is also extended to characterize linear loss in waveguides. A model of nonlinear effects in Bragg reflector resonators manifesting in bistability is also developed, as this phenomenon can be detrimental to the characterization method. Specific recommendations are made regarding waveguide fabrication and experimental design to reduce sources of experimental error.

  15. 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.

  16. Fiber optic micro sensor for the measurement of tendon forces

    Directory of Open Access Journals (Sweden)

    Behrmann Gregory P

    2012-10-01

    Full Text Available Abstract A fiber optic sensor developed for the measurement of tendon forces was designed, numerically modeled, fabricated, and experimentally evaluated. The sensor incorporated fiber Bragg gratings and micro-fabricated stainless steel housings. A fiber Bragg grating is an optical device that is spectrally sensitive to axial strain. Stainless steel housings were designed to convert radial forces applied to the housing into axial forces that could be sensed by the fiber Bragg grating. The metal housings were fabricated by several methods including laser micromachining, swaging, and hydroforming. Designs are presented that allow for simultaneous temperature and force measurements as well as for simultaneous resolution of multi-axis forces. The sensor was experimentally evaluated by hydrostatic loading and in vitro testing. A commercial hydraulic burst tester was used to provide uniform pressures on the sensor in order to establish the linearity, repeatability, and accuracy characteristics of the sensor. The in vitro experiments were performed in excised tendon and in a dynamic gait simulator to simulate biological conditions. In both experimental conditions, the sensor was found to be a sensitive and reliable method for acquiring minimally invasive measurements of soft tissue forces. Our results suggest that this sensor will prove useful in a variety of biomechanical measurements.

  17. Fiber optic stress-independent helical torsion sensor.

    Science.gov (United States)

    Fernandes, Luís A; Grenier, Jason R; Aitchison, J Stewart; Herman, Peter R

    2015-02-15

    Femtosecond laser-fabricated waveguides have been formed into helical paths throughout the cladding of single-mode optical fibers to demonstrate a strain-independent fiber torsion sensor. A comparison between a Bragg grating sensor and a Mach-Zehnder based on helical waveguides (HWs) showed a much weaker twist sensitivity of 1.5 pm/(rad/m) for the grating in contrast with a value of 261 pm/(rad/m) for the interferometer. The HW geometry provided an unambiguous determination of the rotational direction of the twist while facilitating a convenient and efficient means for optical coupling into the single-mode core of the fiber. The flexible three-dimensional writing by the femtosecond laser fabrication method enabled the direct inscription of compact and robust optical cladding devices without the need for combining or splicing multiple-fiber segments.

  18. Probing the ultimate limit of fiber-optic strain sensing.

    Science.gov (United States)

    Gagliardi, G; Salza, M; Avino, S; Ferraro, P; De Natale, P

    2010-11-19

    The measurement of relative displacements and deformations is important in many fields such as structural engineering, aerospace, geophysics, and nanotechnology. Optical-fiber sensors have become key tools for strain measurements, with sensitivity limits ranging between 10(-9) and 10(-6)ε hertz (Hz)(-1/2) (where ε is the fractional length change). We report on strain measurements at the 10(-13)ε-Hz(-1/2) level using a fiber Bragg-grating resonator with a diode-laser source that is stabilized against a quartz-disciplined optical frequency comb, thus approaching detection limits set by thermodynamic phase fluctuations in the fiber. This scheme may provide a route to a new generation of strain sensors that is entirely based on fiber-optic systems, which are aimed at measuring fundamental physical quantities; for example, in gyroscopes, accelerometers, and gravity experiments.

  19. High efficiency holographic Bragg grating with optically prolonged memory

    Science.gov (United States)

    Khoo, Iam Choon; Chen, Chun-Wei; Ho, Tsung-Jui

    2016-10-01

    In this paper, we show that photosensitive azo-dye doped Blue-phase liquid crystals (BPLC) formed by natural molecular self-assembly are capable of high diffraction efficiency holographic recording with memory that can be prolonged from few seconds to several minutes by uniform illumination with the reference beam. Operating in the Bragg regime, we have observed 50 times improvement in the grating diffraction efficiency and shorter recording time compared to previous investigations. The enabling mechanism is BPLC’s lattice distortion and index modulation caused by the action of light on the azo-dopant; upon photo-excitation, the azo-molecules undergo transformation from the oblong-shaped Trans-state to the bent-shaped Cis-state, imparting disorder and also cause the surrounding BPLC molecules to undergo coupled flow & reorientation leading to lattice distortion and index modulation. We also showed that the same mechanism at work here that facilitates lattice distortion can be used to frustrate free relaxation of the lattice distortion, thereby prolonging the lifetime of the written grating, provided the reference beam is kept on after recording. Due to the ease in BPLC fabrication and the availability of azo-dopants with photosensitivity throughout the entire visible spectrum, one can optimize the controlling material and optical parameters to obtain even better performance.

  20. 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.

  1. Fiber optic to integrated optical chip coupler

    Science.gov (United States)

    Pikulski, Joseph I. (Inventor); Ramer, O. Glenn (Inventor)

    1987-01-01

    Optical fibers are clamped by a block onto a substrate. Thereupon, metal is plated over the fibers to hold them in place upon the substrate. The clamp block is removed and the opening, resulting from the clamp block's presence, is then plated in. The built-up metallic body is a coupling which holds the fibers in position so that the ends can be polished for coupling to an integrated optical chip upon a coupling fixture.

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

    Science.gov (United States)

    de Lourenço, Ivo; Possetti, Gustavo R. C.; Muller, Marcia; Fabris, José L.

    2010-01-01

    In this paper, we report a study about the application of packaged fiber Bragg gratings used as strain sensors to monitor the stress kinetics during the drying process of commercial latex paints. Three stages of drying with distinct mechanical deformation and temporal behaviors were identified for the samples, with mechanical deformation from 15 μm to 21 μm in the longitudinal film dimension on time intervals from 370 to 600 minutes. Drying time tests based on human sense technique described by the Brazilian Technical Standards NBR 9558 were also done. The results obtained shows that human sense technique has a limited perception of the drying process and that the optical measurement system proposed can be used to characterize correctly the dry-through stage of paint. The influence of solvent (water) addition in the drying process was also investigated. The paint was diluted with four parts paint and one part water (80% paint), and one part paint and one part water (50% paint). It was observed that the increase of the water ratio mixed into the paint decreases both the mechanical deformation magnitude and the paint dry-through time. Contraction of 5.2 μm and 10.4 μm were measured for concentrations of 50% and 80% of paint in the mixture, respectively. For both diluted paints the dry-through time was approximately 170 minutes less than undiluted paint. The optical technique proposed in this work can contribute to the development of new standards to specify the drying time of paint coatings. PMID:22399906

  3. Fundamentals of plastic optical fibers

    CERN Document Server

    Koike, Yasuhiro

    2014-01-01

    Polymer photonics is an interdisciplinary field which demands excellence both in optics (photonics) and materials science (polymer). However, theses disciplines have developed independently, and therefore the demand for a comprehensive work featuring the fundamentals of photonic polymers is greater than ever.This volume focuses on Polymer Optical Fiber and their applications. The first part of the book introduces typical optical fibers according to their classifications of material, propagating mode, and structure. Optical properties, the high bandwidth POF and transmission loss are discussed,

  4. Sensing system with Michelson-type fiber optical interferometer based on single FBG reflector

    Institute of Scientific and Technical Information of China (English)

    Xueliang Zhang; Zhou Meng; Zhengliang Hu

    2011-01-01

    A sensing system, with Michelson-type fiber optical interferometer based on single fiber Bragg grating (FBG) as the reflector, is demonstrated. The system used a frequency-matched ring fiber optical laser as the source. The closed Michelson-type fiber optical interferometer system will be helpful in simplifying the developed interferometric sensor by replacing the double reflectors with only one FBG reflecting the double-side light. The basic sensing properties of the system are demonstrated, with a fiber optic piezoelectric ceramic transducer embedded in the arm of the interferometer simulating the sensing signal.%As a simple fiber optic component,fiber Bragg grating (FBG) has been used frequently as a sensor,filter or reflector[1-4],etc.Meanwhile,the Michelson-type fiber optical interferometric sensor has achieved a high level of development in the acoustic,electric,and magnetic field sensors because of its simple and low-cost structure as well as multiplexing advantages.The Michelsontype interferometer has been widely applied with Faraday rotating mirrors (FRMs) or polarization maintaining fiber reflectors particularly in the fiber optic hydrophone system[5,6].At present,further research is aimed at simplifying fiber optical interferometric sensors.

  5. 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.

  6. 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.

  7. Optical-Fiber Leak Detector

    Science.gov (United States)

    Workman, Gary L.; Kosten, Susan E.

    1994-01-01

    Proposed optical-fiber sensor detects small changes in pressure in elastomeric O-ring or similar pressure seal, which may indicate deterioration of seal and interpreted as indications of incipient failure. According to concept, length of optical fiber embedded in seal. Light-emitting diode illuminates one end of fiber; photodetector measures intensity of light emerging from other end. Pressure-induced changes in seal bend fiber slightly, altering microbending-induced loss of light from fiber and alter intensity of light at photodetector. Change in intensity approximately proportional to change in pressure.

  8. 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.

  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-speed all-optical NAND/AND logic gates using four-wave mixing Bragg scattering.

    Science.gov (United States)

    Li, Kangmei; Ting, Hong-Fu; Foster, Mark A; Foster, Amy C

    2016-07-15

    A high-speed all-optical NAND logic gate is proposed and experimentally demonstrated using four-wave mixing Bragg scattering in highly nonlinear fiber. NAND/AND logic functions are implemented at two wavelengths by encoding logic inputs on two pumps via on-off keying. A 15.2-dB depletion of the signal is obtained for NAND operation, and time domain measurements show 10-Gb/s NAND/AND logic operations with open eye diagrams. The approach can be readily extended to higher data rates and transferred to on-chip waveguide platforms.

  11. Quantum cryptography using optical fibers.

    Science.gov (United States)

    Franson, J D; Lives, H

    1994-05-10

    Quantum cryptography permits the transmission of secret information whose security is guaranteed by the uncertainty principle. An experimental system for quantum crytography is implemented based on the linear polarization of single photons transmitted by an optical fiber. Polarization-preserving optical fiber and a feedback loop are employed to maintain the state of polarization. Error rates of less than 0.5% are obtained.

  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. 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

  15. Fiber-optically sensorized composite wing

    Science.gov (United States)

    Costa, Joannes M.; Black, Richard J.; Moslehi, Behzad; Oblea, Levy; Patel, Rona; Sotoudeh, Vahid; Abouzeida, Essam; Quinones, Vladimir; Gowayed, Yasser; Soobramaney, Paul; Flowers, George

    2014-04-01

    Electromagnetic interference (EMI) immune and light-weight, fiber-optic sensor based Structural Health Monitoring (SHM) will find increasing application in aerospace structures ranging from aircraft wings to jet engine vanes. Intelligent Fiber Optic Systems Corporation (IFOS) has been developing multi-functional fiber Bragg grating (FBG) sensor systems including parallel processing FBG interrogators combined with advanced signal processing for SHM, structural state sensing and load monitoring applications. This paper reports work with Auburn University on embedding and testing FBG sensor arrays in a quarter scale model of a T38 composite wing. The wing was designed and manufactured using fabric reinforced polymer matrix composites. FBG sensors were embedded under the top layer of the composite. Their positions were chosen based on strain maps determined by finite element analysis. Static and dynamic testing confirmed expected response from the FBGs. The demonstrated technology has the potential to be further developed into an autonomous onboard system to perform load monitoring, SHM and Non-Destructive Evaluation (NDE) of composite aerospace structures (wings and rotorcraft blades). This platform technology could also be applied to flight testing of morphing and aero-elastic control surfaces.

  16. Phase-sensitive detection of Bragg scattering at 1D optical lattices

    CERN Document Server

    Slama, S; Deh, B; Ludewig, A; Zimmermann, C; Courteille, P W; Courteille, Ph.W.

    2004-01-01

    We report on the observation of Bragg scattering at 1D atomic lattices. Cold atoms are confined by optical dipole forces at the antinodes of a standing wave generated by the two counter-propagating modes of a laser-driven high-finesse ring cavity. By heterodyning the Bragg-scattered light with a reference beam, we obtain detailed information on phase shifts imparted by the Bragg scattering process. Being deep in the Lamb-Dicke regime, the scattered light is not broadened by the motion of individual atoms. In contrast, we have detected signatures of global translatory motion of the atomic grating.

  17. Fiber optic sensor and method for making

    Science.gov (United States)

    Vartuli, James Scott; Bousman, Kenneth Sherwood; Deng, Kung-Li; McEvoy, Kevin Paul; Xia, Hua

    2010-05-18

    A fiber optic sensor including a fiber having a modified surface integral with the fiber wherein the modified surface includes an open pore network with optical agents dispersed within the open pores of the open pore network. Methods for preparing the fiber optic sensor are also provided. The fiber optic sensors can withstand high temperatures and harsh environments.

  18. Fiber-optic technology review

    Energy Technology Data Exchange (ETDEWEB)

    Lyons, P.B.

    1980-01-01

    A history of fiber technology is presented. The advantages of fiber optics are discussed (bandwidth, cost, weight and size, nonmetallic construction and isolation). Some aspects of the disadvantages of fiber systems briefly discussed are fiber and cable availability, fiber components, radiation effects, receivers and transmitters, and material dispersion. Particular emphasis over the next several years will involve development of fibers and systems optimized for use at wavelengths near 1.3 ..mu..m and development of wavelengths multiplexers for simultaneous system operation at several wavelengths.

  19. 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.

  20. 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.

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

    Science.gov (United States)

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

    2006-03-01

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

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

    Science.gov (United States)

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

    2011-09-01

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

  3. 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.

  4. 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.

  5. Bare Fiber Bragg Gratings embedded into concrete buffer Supercontainer concept for nuclear waste storage [ANIMMA--2015-IO-337

    Energy Technology Data Exchange (ETDEWEB)

    Kinet, Damien; Chah, Karima; Megret, Patrice; Caucheteur, Christophe [University of Mons, Boulevard Dolez 31, 7000 Mons (Belgium); Gusarov, Andrei [SCK-CEN, Boeretang 200, 2400 Mol (Belgium); Faustov, Alexey [University of Mons, Boulevard Dolez 31, 7000 Mons (Belgium); SCK-CEN, Boeretang 200, 2400 Mol (Belgium); Areias, Lou [Department Mechanics of Materials and Constructions - MeMC, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels (Belgium); EIG EURIDICE - European Underground Research Infrastructure for Disposal of nuclear waste In Clay Environment, Boeretang 200, 2400 Mol (Belgium)

    2015-07-01

    Nuclear power plants have been generating electricity for more than 50 years. In Belgium, 55% of the current energy supply comes from nuclear power. Providing for the safe storage of nuclear waste, including spent fuel (SF) and vitrified high level radioactive waste (HLW), remains an important challenge in the life cycle of nuclear fuel. In this context, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials (ONDRAF/NIRAS) is investigating a reference conceptual design called the Supercontainer (SC) for the packaging of SF and HLW. This conceptual design is based on a multiple-barrier system consisting of a hermetically-sealed carbon steel overpack and a surrounding highly-alkaline concrete buffer. The first one is developed to retain the radionuclides. The two main functions of the buffer are (a) to create a high pH environment around the carbon steel overpack in order to passivate the metal surface and so to slow down the corrosion propagation during the thermal phase and (b) to provide a radiological shielding during the construction and the handling of the Supercontainer. A recent test has been performed to investigate the feasibility to construct the SC. This test incorporated several kinds of sensors including Digital Image Correlation (DIC), Acoustic Emission (AE), corrosion sensing techniques and optical fibers with and without fiber Bragg gratings (FBGs). In particular, several single-mode optical fibers with 4 mm long FBGs with different Bragg wavelengths and distributed along the optical fibers were used. For casting and curing condition monitoring, a number of gratings were incorporated inside the concrete buffer during the first stage of construction. Then other sensors were embedded near a heat source installed in the second stage to simulate the effects of heat generated by radioactive waste. The FBGs were designed to measure both temperature and strain effects in the concrete. To discriminate between these effects special packaging

  6. Fiber optic hydrogen sensor

    Energy Technology Data Exchange (ETDEWEB)

    Butler, M.A.; Sanchez, R.; Dulleck, G.R.

    1996-05-01

    This report covers the development of fiber optic hydrogen and temperature sensors for monitoring dissolved hydrogen gas in transformer oil. The concentration of hydrogen gas is a measure of the corona and spark discharge within the transformer and reflects the state of health of the transformer. Key features of the instrument include use of palladium alloys to enhance hydrogen sensitivity, a microprocessor controlled instrument with RS-232, liquid crystal readout, and 4-20 ma. current loop interfaces. Calibration data for both sensors can be down loaded to the instrument through the RS-232 interface. This project was supported by the Technology Transfer Initiative in collaboration with J. W. Harley, Inc. through the mechanism of a cooperative research and development agreement (CRADA).

  7. Novel Knob-integrated fiber Bragg grating sensor with polyvinyl alcohol coating for simultaneous relative humidity and temperature measurement.

    Science.gov (United States)

    Yan, Guofeng; Liang, Yanhong; Lee, El-Hang; He, Sailing

    2015-06-15

    A novel high performance optical fiber sensor for simultaneous measurement of relative humidity (RH) and temperature based on our newly designed knob-integrated fiber Bragg grating (FBG) is proposed and experimentally demonstrated. The knob-shaped taper followed by an FBG works as a multifunctional joint that not only excites the cladding modes but also recouples the cladding modes reflected by the FBG back into the leading single mode fiber. Polyvinyl alcohol (PVA) film is plated on the fiber surface by dip-coating technique as a humidity-to-refractive index (RI) transducer, and affects the intensity of reflected cladding modes by way of evanescent fields. By monitoring the intensity and wavelength of the reflected cladding modes, the RH and temperature variance can be determined simultaneously. Experimental results show an RH sensitivity of up to 1.2 dB/%RH within an RH range of 30-95%, which is significantly better than previously reported values. And the temperature sensitivity of 8.2 pm/°Ccould be achieved in the temperature range of 25-60°C. A fast and reversible time response has also been demonstrated, enabling to pick up a humidity change as fast as 630 ms. The capability of simultaneous measurement of RH and temperature, the fast response, the reusability and the simple fabrication process make this structure a highly promising sensor for real-time practical RH monitoring applications.

  8. Structural Health Monitoring with Fiber Bragg Grating and Piezo Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Intelligent Fiber Optic Systems Corporation (IFOS) in collaboration with Washington State University (WSU) proposes an approach of utilizing structurally integrated,...

  9. 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).

  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. 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

  12. Gold island fiber optic sensor

    Science.gov (United States)

    Meriaudeau, Fabrice; Wig, A. G.; Passian, A.; Downey, Todd R.; Buncick, Milan; Ferrell, Trinidad L.

    1999-12-01

    A fiber optic chemical sensor based on gold-island surface plasmon excitation is presented. The sensing part of the fiber is the end of the fiber onto which a thin layer of gold has been deposited to form a particulate surface. Annealing the gold reshapes the particles and produces an optical absorbance near 535 nm with the fiber in air. The optical absorption resonance of the gold particles is shifted if the fiber is immersed in a medium other than air. These resonance shifts are examined by transmission spectroscopy through the fiber. Experimental results for the sensitivity and dynamic range in the measurement of liquid solutions are in agreement with a basic theoretical model which characterizes the surface plasmon using nonretarded electrodynamics.

  13. 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.

  14. 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.

  15. 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.

  16. 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%.

  17. Embedded fiber Bragg grating sensors for true temperature monitoring in Nb$_3$Sn superconducting magnets for high energy physics

    CERN Document Server

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

    2016-01-01

    The luminosity upgrade of the Large Hadron Collider (HL-LHC) planned at the European Organization for Nuclear Research (CERN) requires the development of a new generation of superconducting magnets based on Nb3Sn technology. The instrumentation required for the racetrack coils needs the development of reliable sensing systems able to monitor the magnet thermo-mechanical behavior during its service life, from the coil fabrication to the magnet operation. With this purpose, Fiber Bragg Grating (FBG) sensors have been embedded in the coils of the Short Model Coil (SMC) magnet fabricated at CERN. The FBG sensitivity to both temperature and strain required the development of a solution able to separate mechanical and temperature effects. This work presents for the first time a feasibility study devoted to the implementation of an embedded FBG sensor for the measurement of the "true" temperature in the impregnated Nb3Sn coil during the fabrication process. © (2016) COPYRIGHT Society of Photo-Optical Instrumentatio...

  18. Fiber optic-based biosensor

    Science.gov (United States)

    Ligler, Frances S.

    1991-01-01

    The NRL fiber optic biosensor is a device which measures the formation of a fluorescent complex at the surface of an optical fiber. Antibodies and DNA binding proteins provide the mechanism for recognizing an analyze and immobilizing a fluorescent complex on the fiber surface. The fiber optic biosensor is fast, sensitive, and permits analysis of hazardous materials remote from the instrumentation. The fiber optic biosensor is described in terms of the device configuration, chemistry for protein immobilization, and assay development. A lab version is being used for assay development and performance characterization while a portable device is under development. Antibodies coated on the fiber are stable for up to two years of storage prior to use. The fiber optic biosensor was used to measure concentration of toxins in the parts per billion (ng/ml) range in under a minute. Immunoassays for small molecules and whole bacteria are under development. Assays using DNA probes as the detection element can also be used with the fiber optic sensor, which is currently being developed to detect biological warfare agents, explosives, pathogens, and toxic materials which pollute the environment.

  19. 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...

  20. 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...