Showing papers on "Fiber Bragg grating published in 2011"
Patent•
16 Mar 2011TL;DR: In this paper, a detection system coupled with the optical fiber bend sensor was proposed to determine a position of at least one joint region of an articulatable arm based on the detected light reflected by or transmitted through the sensor, and a control system comprising a servo controller for effectuating movement of the arm.
Abstract: A surgical instrument is provided, including: at least one articulatable arm having a distal end, a proximal end, and at least one joint region disposed between the distal and proximal ends; an optical fiber bend sensor provided in the at least one joint region of the at least one articulatable arm; a detection system coupled to the optical fiber bend sensor, said detection system comprising a light source and a light detector for detecting light reflected by or transmitted through the optical fiber bend sensor to determine a position of at least one joint region of the at least one articulatable arm based on the detected light reflected by or transmitted through the optical fiber bend sensor; and a control system comprising a servo controller for effectuating movement of the arm.
986 citations
TL;DR: The progress on improving sensing performance parameters like spatial resolution, sensing length limitation and simultaneous temperature and strain measurement is reviewed.
Abstract: Brillouin scattering in optical fiber describes the interaction of an electro-magnetic field (photon) with a characteristic density variation of the fiber. When the electric field amplitude of an optical beam (so-called pump wave), and another wave is introduced at the downshifted Brillouin frequency (namely Stokes wave), the beating between the pump and Stokes waves creates a modified density change via the electrostriction effect, resulting in so-called the stimulated Brillouin scattering. The density variation is associated with a mechanical acoustic wave; and it may be affected by local temperature, strain, and vibration which induce changes in the fiber effective refractive index and sound velocity. Through the measurement of the static or dynamic changes in Brillouin frequency along the fiber one can realize a distributed fiber sensor for local temperature, strain and vibration over tens or hundreds of kilometers. This paper reviews the progress on improving sensing performance parameters like spatial resolution, sensing length limitation and simultaneous temperature and strain measurement. These kinds of sensors can be used in civil structural monitoring of pipelines, bridges, dams, and railroads for disaster prevention. Analogous to the static Bragg grating, one can write a moving Brillouin grating in fibers, with the lifetime of the acoustic wave. The length of the Brillouin grating can be controlled by the writing pulses at any position in fibers. Such gratings can be used to measure changes in birefringence, which is an important parameter in fiber communications. Applications for this kind of sensor can be found in aerospace, material processing and fine structures.
491 citations
TL;DR: In this paper, the phase-displacement relation of a single-mode POF undergoing large deformation is presented to build a fundamental understanding of the response of single mode POF sensors.
Abstract: Polymer optical fibers (POFs) have significant advantages for many sensing applications, including high elastic strain limits, high fracture toughness, high flexibility in bending, high sensitivity to strain and potential negative thermo-optic coefficients. The recent emergence of single-mode POFs has enabled high precision, large deformation optical fiber sensors. This article describes recent advances in both multi-mode and single-mode POF based strain and temperature sensors. The mechanical and optical properties of POFs relevant to strain and temperature applications are first summarized. POFs considered include multi-mode POFs, solid core single-mode POFs and microstructured single-mode POFs. Practical methods for applying POF sensors, including connecting and embedding sensors in structural materials, are also described. Recent demonstrations of multi-mode POF sensors in structural applications based on new interrogation methods, including backscattering and time-of-flight measurements, are outlined. The phase‐displacement relation of a single-mode POF undergoing large deformation is presented to build a fundamental understanding of the response of single-mode POF sensors. Finally, this article highlights recent single-mode POF based sensors based on polymer fiber Bragg gratings and microstructured POFs. (Some figures in this article are in colour only in the electronic version)
454 citations
TL;DR: This review paper covers the aerospace SHM requirements and an overview of the fiber optic sensor technologies and recommendations on the implementation and integration of FBG sensors into an SHM system are provided.
Abstract: Aircraft operators are faced with increasing requirements to extend the service life of air platforms beyond their designed life cycles, resulting in heavy maintenance and inspection burdens as well as economic pressure. Structural health monitoring (SHM) based on advanced sensor technology is potentially a cost-effective approach to meet operational requirements, and to reduce maintenance costs. Fiber optic sensor technology is being developed to provide existing and future aircrafts with SHM capability due to its unique superior characteristics. This review paper covers the aerospace SHM requirements and an overview of the fiber optic sensor technologies. In particular, fiber Bragg grating (FBG) sensor technology is evaluated as the most promising tool for load monitoring and damage detection, the two critical SHM aspects of air platforms. At last, recommendations on the implementation and integration of FBG sensors into an SHM system are provided.
260 citations
TL;DR: In this paper, techniques to generate microwave arbitrary waveforms based on all-fiber solutions are reviewed, with an emphasis on the system architectures based on direct space-to-time pulse shaping, spectral-shaping and wavelength to-time mapping, temporal pulse shaping and photonic microwave delay-line filtering.
249 citations
TL;DR: Characterization of the FBGs shows that the TOPAS FBG is more than 50 times less sensitive to humidity than the conventional PMMA FBG in both wavelength regimes, which makes the TOPas FBG very appealing for sensing applications as it appears to solve the humidity sensitivity problem suffered by the PMMAFBG.
Abstract: We report the first experimental demonstration of a humidity insensitive polymer optical fiber Bragg grating (FBG), as well as the first FBG recorded in a TOPAS polymer optical fiber in the important low loss 850nm spectral region. For the demonstration we have fabricated FBGs with resonance wavelength around 850 nm and 1550 nm in single-mode microstructured polymer optical fibers made of TOPAS and the conventional poly (methyl methacrylate) (PMMA). Characterization of the FBGs shows that the TOPAS FBG is more than 50 times less sensitive to humidity than the conventional PMMA FBG in both wavelength regimes. This makes the TOPAS FBG very appealing for sensing applications as it appears to solve the humidity sensitivity problem suffered by the PMMA FBG.
240 citations
TL;DR: A highly sensitive compact hydrophone, based on a pi-phase-shifted fiber Bragg grating, has been developed for the measurement of wideband ultrasonic fields, which makes the design attractive for medical imaging applications, such as optoacoustic tomography, in which compact, sensitive, and wideband acoustic detectors are required.
Abstract: A highly sensitive compact hydrophone, based on a pi-phase-shifted fiber Bragg grating, has been developed for the measurement of wideband ultrasonic fields. The grating exhibits a sharp resonance, whose centroid wavelength is pressure sensitive. The resonance is monitored by a continuous-wave (CW) laser to measure ultrasound-induced pressure variations within the grating. In contrast to standard fiber sensors, the high finesse of the resonance--which is the reason for the sensor's high sensitivity--is not associated with a long propagation length. Light localization around the phase shift reduces the effective size of the sensor below that of the grating and is scaled inversely with the resonance spectral width. In our system, an effective sensor length of 270 μm, pressure sensitivity of 440 Pa, and effective bandwidth of 10 MHz were achieved. This performance makes our design attractive for medical imaging applications, such as optoacoustic tomography, in which compact, sensitive, and wideband acoustic detectors are required.
234 citations
TL;DR: A review of various application areas of fiber grating based devices, the status of precedent and ongoing research around the world, and discussion on the issues hampering their rapid growth in the field are reviewed.
Abstract: Fiber grating sensors hold immense potential for biomedical applications due to their inherent properties like small size, biocompatibility, non-toxicity, chemical inertness and electromagnetically inert nature. Grating based sensors are well known technology for structural health monitoring (SHM) in the arena of civil and aerospace; however investigations for their use in the field of medicine are fairly recent and they have not been yet commercialized for the same. As these sensors detect strain, temperature, pressure, vibration, curvature and refractive index of the surrounding material even in high magnetic and electric field environments, they can serve diagnostic purposes in diverse areas of healthcare e.g. biomechanics, cardiology, gynecology, very low temperature monitoring and immunosensing to name a few. Most importantly, they can be used efficiently for thermal and pressure mapping even during MRI procedure where conventional sensors may fail. The paper is a review of various application areas of fiber grating based devices, the status of precedent and ongoing research around the world, and discussion on the issues hampering their rapid growth in the field.
233 citations
TL;DR: In this article, the authors presented a random fiber laser that is tunable over a broad wavelength range with uniquely flat output power and high efficiency, which outperforms traditional lasers of the same category.
Abstract: An optical fiber is treated as a natural one-dimensional random system where lasing is possible due to a combination of Rayleigh scattering by refractive index inhomogeneities and distributed amplification through the Raman effect. We present such a random fiber laser that is tunable over a broad wavelength range with uniquely flat output power and high efficiency, which outperforms traditional lasers of the same category. Outstanding characteristics defined by deep underlying physics and the simplicity of the scheme make the demonstrated laser a very attractive light source both for fundamental science and practical applications.
215 citations
TL;DR: To the best of the knowledge, this is the first report for passively Q-switched sub-100-ns pulse operation of a graphene-based saturable absorber in a Yb-doped fiber laser.
Abstract: We demonstrate stable 70 ns pulse generation from a Yb-doped fiber laser passively Q-switched by a graphene-based saturable absorber mirror in a short linear cavity. The maximum output power was 12 mW and the highest single pulse energy was 46 nJ. The repetition rate of the fiber laser can be widely tuned from 140 to 257 kHz along with the increase of the pump power. To the best of our knowledge, this is the first report for passively Q-switched sub-100-ns pulse operation of a graphene-based saturable absorber in a Yb-doped fiber laser.
210 citations
TL;DR: A high-temperature sensor based on a Mach-Zehnder interferometer (MZI) in a conventional single-mode optical fiber is proposed and fabricated by concatenating two microcavities separated by a middle section.
Abstract: A high-temperature sensor based on a Mach–Zehnder interferometer (MZI) in a conventional single-mode optical fiber is proposed and fabricated by concatenating two microcavities separated by a middle section A femtosecond laser is used to fabricate a microhole on the center of a fiber end Then a micro-air-cavity is formed by splicing the microholed fiber end with a normal fiber end The interferometer is applied for high-temperature sensing, in the range of 500–1200 °C, with a sensitivity of 109 pm/°C that, to the best of our knowledge, is highest in silica fiber temperature sensors Also, the interferometer is insensitive to external refractive index (RI), which is desirable for temperature sensors
TL;DR: The incoherent beam combination of the four narrow-linewidth fiber amplifier chains running at different wavelengths using a polarization-independent dielectric reflective diffraction grating mainly preserving the beam quality of the individual fiber amplifiers.
Abstract: We report on the incoherent beam combination of the four narrow-linewidth fiber amplifier chains running at different wavelengths Each main amplifier stage consists of a large-mode-area photonic crystal fiber delivering more than 2 kW of optical power The four output beams are spectrally combined to a single beam with an output power of 82 kW using a polarization-independent dielectric reflective diffraction grating mainly preserving the beam quality of the individual fiber amplifiers
TL;DR: In this article, a novel fiber optical fiber-magnetic sensor based on magnetic fluid was proposed in which the stable nanoparticles Fe3O4 magnetic fluid is synthesized firstly; the Fe 3O4 magnetometer was injected in capillaries containing etched fiber Bragg grating (FBG) as sensing element.
TL;DR: A fiber Mach-Zehnder interferometer sensor based on a single "S"-like fiber taper has been fabricated via applying nonaxial pull in fiber tapering by a fusion splicer, which has a refractive index sensitivity 30 times higher than that of the normal two-taper-based MZI sensors.
Abstract: A fiber Mach–Zehnder interferometer (MZI) sensor, novel to our knowledge, based on a single “S”-like fiber taper has been fabricated via applying nonaxial pull in fiber tapering by a fusion splicer. The typical feature size of the structure has a length of 660 μm and the axial offset of 96 μm. This S fiber taper MZI has a refractive index (RI) sensitivity of 1590 nm/refractive index unit in the RI range of 1.409–1.425 and a strain sensitivity of about −60 pm/microstrain, which is 30 times higher than that of the normal two-taper-based MZI sensors.
TL;DR: In this paper, the authors review the work on efficient interfaces between a silicon-on-insulator photonic IC and a single-mode optical fiber based on grating structures and present several device configurations that provide high efficiency, polarization insensitive, and broadband optical coupling on a small footprint.
Abstract: In this paper, we review our work on efficient interfaces between a silicon-on-insulator photonic IC and a single-mode optical fiber based on grating structures. Several device configurations are presented that provide high efficiency, polarization insensitive, and broadband optical coupling on a small footprint. The high alignment tolerance and the fact that the optical fiber interface is out-of-plane provide opportunities for easy packaging and wafer-scale testing of the photonic IC. Finally, an optical probe based on a grating structure defined on the fiber facet is described.
TL;DR: In this paper, a detailed study of the inscription and characterization of fiber Bragg gratings (FBGs) in commercial step index polymer optical fibers (POFs) was performed. And they found that FBGs in annealed commercial POFs can offer more stable short-term performance at both higher temperature and larger strain.
TL;DR: In this article, a signal demodulation algorithm based on the cross correlation and mean square error (MSE) estimation has been proposed for retrieving the cavity length of EFPI.
Abstract: Pressure sensors based on fiber-optic extrinsic Fabry-Perot interferometer (EFPI) have been extensively applied in various industrial and biomedical fields. In this paper, some key improvements of EFPI-based pressure sensors such as the controlled thermal bonding technique, diaphragm-based EFPI sensors, and white light interference technology have been reviewed. Recent progress on signal demodulation method and applications of EFPI-based pressure sensors has been introduced. Signal demodulation algorithms based on the cross correlation and mean square error (MSE) estimation have been proposed for retrieving the cavity length of EFPI. Absolute measurement with a resolution of 0.08 nm over large dynamic range has been carried out. For downhole monitoring, an EFPI and a fiber Bragg grating (FBG) cascade multiplexing fiber-optic sensor system has been developed, which can operate in temperature 300 °C with a good long-term stability and extremely low temperature cross-sensitivity. Diaphragm-based EFPI pressure sensors have been successfully used for low pressure and acoustic wave detection. Experimental results show that a sensitivity of 31 mV/Pa in the frequency range of 100 Hz to 12.7 kHz for aeroacoustic wave detection has been obtained.
TL;DR: The Jones matrix associated to the TFBG transmission properties is measured in order to be able to analyze different polarization-related parameters (i.e. dependency on wavelength of polarization dependent loss and first Stokes parameter) and the maximum error on refractive index measurement has been determined to be 5 times better than intensity-based measurements on the same sensors.
Abstract: The generation of surface plasmon resonances (SPRs) in gold-coated weakly tilted fiber Bragg gratings (TFBGs) strongly depends on the state of polarization of the core guided light Recently, it was demonstrated that rotating the linear state of polarization of the guided light by 90° with respect to the grating tilt allows to turn the SPR on and off In this work, we measure the Jones matrix associated to the TFBG transmission properties in order to be able to analyze different polarization-related parameters (ie dependency on wavelength of polarization dependent loss and first Stokes parameter) As they contain the information about the SPR, they can be used as a robust and accurate demodulation technique for refractometry purposes Unlike other methods reported so far, a tight control of the input state of polarization is not required The maximum error on refractive index measurement has been determined to be ~1 10−5 refractive index unit (RIU), 5 times better than intensity-based measurements on the same sensors
TL;DR: A highly sensitive refractive index (RI) sensor based on three cascaded single-mode fiber tapers, in which a weak taper is sandwiched between the two tapers to improve the sensitivity of the sensor.
Abstract: We report a highly sensitive refractive index (RI) sensor based on three cascaded single-mode fiber tapers, in which a weak taper is sandwiched between the two tapers to improve the sensitivity of the sensor. Experimental results show that the sensitivity of the device is 0.286 nm for a 0.01 RI change, which is about four times higher than that of the normal two-cascaded-taper-based Mach–Zehnder interferometer. In addition, the sensitivity of the device could be enhanced by tapering a longer and thinner middle weak taper. Such kinds of low-cost and highly sensitive fiber-optic RI sensors would find applications in chemical or biochemical sensing fields.
TL;DR: The fiber biosensor presented in this study utilizes an in-fiber tilted Bragg grating to excite the SPR on the surface of the sensor over a large range of external medium refractive indices, with minimal cross-sensitivity to temperature and without compromising the structural integrity of the fiber.
Abstract: Surface plasmon resonance (SPR) biosensors prepared using optical fibers can be used as a cost-effective and relatively simple-to-implement alternative to well established biosensor platforms for monitoring biomolecular interactions in situ or possibly in vivo. The fiber biosensor presented in this study utilizes an in-fiber tilted Bragg grating to excite the SPR on the surface of the sensor over a large range of external medium refractive indices, with minimal cross-sensitivity to temperature and without compromising the structural integrity of the fiber. The label-free biorecognition scheme used demonstrates that the sensor relies on the functionalization of the gold-coated fiber with aptamers, synthetic DNA sequences that bind with high specificity to a given target. In addition to monitoring the functionalization of the fiber by the aptamers in real-time, the results also show how the fiber biosensor can detect the presence of the aptamer’s target, in various concentrations of thrombin in buffer and s...
TL;DR: In this paper, a serial time-division-multiplexing sensor network based on ultra-weak fiber Bragg gratings (FBGs) is proposed, where the low crosstalk of the gratings makes it possible to multiplex over 1000 gratings along a single optical fiber.
Abstract: We propose a serial time-division-multiplexing sensor network based on ultraweak fiber Bragg gratings (FBGs). Twelve ultraweak FBGs are distinguished with a spatial resolution of about 0.2 m, and their spectra are resolved with an accuracy of about 10 pm. The low crosstalk of the gratings makes it possible to multiplex over 1000 gratings along a single optical fiber.
TL;DR: The current status of the fiber Bragg grating (FBG) sensor technology was reviewed, and the sensing principle of FBG sensors was briefly introduced first and the wavelength interrogation methods were reviewed carefully.
Abstract: The current status of the fiber Bragg grating (FBG) sensor technology was reviewed. Owing to their salient advantages, including immunity to electromagnetic interference, lightweight, compact size, high sensitivity, large operation bandwidth, and ideal multiplexing capability, FBG sensors have attracted considerable interest in the past three decades. Among these sensing physical quantities, temperature and strain are the most widely investigated ones. In this paper, the sensing principle of FBG sensors was briefly introduced first. Then, we reviewed the status of research and applications of FBG sensors. As very important for industrial applications, multiplexing and networking of FBG sensors had been introduced briefly. Moreover, as a key technology, the wavelength interrogation methods were also reviewed carefully. Finally, we analyzed the problems encountered in engineering applications and gave a general review on the development of interrogation methods of FBG sensor.
TL;DR: Experimental results reveal that the proposed FBG-based anemometer exhibits very good performance for wind speed measurement.
Abstract: 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.
TL;DR: A Raman fiber laser based on multiple point-action fiber Bragg grating reflectors and distributed feedback via Rayleigh scattering in an ~22-km-long optical fiber exhibits highly stable multiwavelength generation with a power-equalized uniform distribution, which is almost independent on power.
Abstract: We experimentally demonstrate a Raman fiber laser based on multiple point-action fiber Bragg grating reflectors and distributed feedback via Rayleigh scattering in an ∼22-km-long optical fiber. Twenty-two lasing lines with spacing of ∼100 GHz (close to International Telecommunication Union grid) in the C band are generated at the watt level. In contrast to the normal cavity with competition between laser lines, the random distributed feedback cavity exhibits highly stable multiwavelength generation with a power-equalized uniform distribution, which is almost independent on power. © 2011 Optical Society of America.
TL;DR: This work reports a first dissipative dispersive-managed soliton fiber laser operating at 2 μm, which employs chirped fiber Bragg grating and ensures net-normal cavity dispersion and semiconductor saturable absorber for mode-locking.
Abstract: We report a first dissipative dispersive-managed soliton fiber laser operating at 2 μm The cavity comprised of all-anomalous-dispersion fiber employs chirped fiber Bragg grating, which ensures net-normal cavity dispersion and semiconductor saturable absorber for mode-locking
TL;DR: In this article, a 3D finite element numerical analysis of the sensor, packaging and adhesive used to fix the system to the host structure was conducted to study the influence of the thickness and mechanical properties of the adhesive, and the configuration of the packaging on the accuracy of the sensors.
TL;DR: A refractive index (RI) sensor based on a novel fiber structure that consists of a single-mode-multimode-single-mode (SMS) fiber structure followed by a fiber Bragg grating was demonstrated.
Abstract: A refractive index (RI) sensor based on a novel fiber structure that consists of a single-mode-multimode-single-mode (SMS) fiber structure followed by a fiber Bragg grating was demonstrated The multimode fiber in the SMS structure excites cladding modes within output single-mode fiber (SMF) and recouple the reflected cladding Bragg wavelength to the input SMF core By measuring the relative Bragg wavelength shift between core and cladding Bragg wavelengths, the RI can be determined Experimentally we have achieved a maximum sensitivity of 733 nm/RIU (RI unit) at RI range from 1324 to 1439
TL;DR: An all-silica first-order fiber Bragg grating for high temperature sensing by focused ion beam (FIB) machining in a fiber probe tapered to a point shows a temperature sensitivity of nearly 20 pm/°C near the resonant wavelength of 1550 nm.
Abstract: We experimentally demonstrate an all-silica first-order fiber Bragg grating (FBG) for high temperature sensing by focused ion beam (FIB) machining in a fiber probe tapered to a point. This 61-period FBG is compact (~36.6 μm long and ~6.5 μm in diameter) with 200-nm-deep shallow grooves. We have tested the sensor from room temperature to around 500 °C and it shows a temperature sensitivity of nearly 20 pm/°C near the resonant wavelength of 1550 nm. This kind of sensor takes up little space because of its unique geometry and small size and may be integrated in devices that work in harsh environment or for detecting small objects.
TL;DR: The highly compact MFBGs demonstrated here may serve as low-dimensional building blocks for miniaturized photonic components and devices.
Abstract: We fabricate fiber Bragg grating (FBG) in microfibers (MFs) using focused ion beam milling technique. By periodically etching 100 nm-depth grooves on the surface of silica MFs with diameters less than 2 μm, evident grating features with transmission dip up to 15 dB are obtained. Because of the high-index contrast of the gratings structure, the length of the microfiber Bragg grating (MFBG) can be reduced to 500 μm level. Using a 518 μm-length 1.8 μm-diameter MFBG, we also demonstrate sensitivity up to 660 nm per refractive index unit (RIU) for refractive index (RI) sensing. The highly compact MFBGs demonstrated here may serve as low-dimensional building blocks for miniaturized photonic components and devices.
Patent•
19 Aug 2011TL;DR: In this paper, the optical fiber is configured to scatter guided light via the nano-sized structures away from the core and through the outer surface, to form a light source fiber portion having a length that emits substantially uniform radiation over its length, said fiber having a scattering-induced attenuation greater than 50 dB/km for the wavelength(s) within 200 nm to 2000 nm range.
Abstract: An illumination system generating light having at least one wavelength within 200 nm a plurality of nano-sized structures (e.g., voids). The optical fiber coupled to the light source. The light diffusing optical fiber has a core and a cladding. The plurality of nano-sized structures is situated either within said core or at a core-cladding boundary. The optical fiber also includes an outer surface. The optical fiber is configured to scatter guided light via the nano-sized structures away from the core and through the outer surface, to form a light-source fiber portion having a length that emits substantially uniform radiation over its length, said fiber having a scattering-induced attenuation greater than 50 dB/km for the wavelength(s) within 200 nm to 2000 nm range.