Fiber Optic Polarimetric Sensor Research Articles

Vibration-insensitive polarimetric fiber optic current sensor based on orbital angular momentum modes in an air-core optical fiber.

Current or magnetic field sensing is usually achieved by exploiting the Faraday effect of an optical material combined with an interferometric probe that provides the sensitivity. Being interferometric in nature, such sensors are typically sensitive to several other environmental parameters such as vibrations and mechanical disturbances, which, however, inevitably impose the inaccuracy and instability of the detection. Here we demonstrate a polarimetric fiber optic current sensor based on orbital angular momentum modes of an air-core optical fiber. In the fiber, spin-orbit interactions imply that the circular birefringence, which is sensitive to applied currents or resultant magnetic fields, is naturally resilient to mechanical vibrations. The sensor, which effectively measures polarization rotation at the output of a fiber in a magnetic field, exhibits high linearity in the measured signal versus the applied current that induces the magnetic field, with a sensitivity of 0.00128 rad/A and a noise limit of 1×10-5/H z. The measured polarization varies within only ±0.1% under mechanical vibrations with the frequency of up to 800 Hz, validating the robust environmental performance of the sensor.

A Spectrally Interrogated Polarimetric Optical Fiber Sensor for Current Measurement with Temperature Correction

We report on a study of the temperature dependence of the response of a BSO crystal based polarimetric current sensor with spectral interrogation. Two possible interrogation schemes are discussed. The spectral dependence of the optical rotation along the crystal caused by temperature and current changes is investigated, and approximate dependences for the sensitivities to current SI and temperature ST are derived. A mixed term in the response with spectral interrogation is revealed, the elimination of which is achieved by tracking wavelength shifts Δλ1 and Δλ2 of two distinct extrema in the polarimetric response. A temperature independent second degree equation for the current changes ΔI as a function of the measured spectral shifts is derived and tested.

A polarimetric fiber optic current sensor based on Bi12SiO20 crystal fluorescence

In this paper, we present a simple fiber optic sensor for magnetic-field/electric current measurement based on broadband fluorescence in a Bi12SiO20 crystal. A simple polarimetric scheme in combination with a standard 105/125 μm multimode fiber, a 405 nm laser diode and a spectrometer to analyze the spectrum is used. The magnetic field induces phase changes measured by the spectral shifts of the wavelength modulated response. The sensitivity is found to be wavelength dependent. It increases from 0.138 nm/A at 540 nm to 0.224 nm/A at 715 nm and is inversely proportional to the Verdet constant. A minimum current of 0.4A can be detected with a dynamic range of up to 32 dB. A detailed polarization analysis is presented.

Simultaneous Current and Vibration Measurement Based on Polarimetric Fiber Optic Sensor

Simultaneous Current and Vibration Measurement Based on Polarimetric Fiber Optic Sensor

Using a fiber optic sensor for registration of pulsed plasma discharge current

The problem of increasing the accuracy of recording the pulse shape of a rapidly changing current of a powerful plasma emitter under conditions of powerful electromagnetic interference is considered. To register high-current pulsed discharges, it is proposed to use a polarimetric fiber-optic current sensor based on a Spun-type fiber. Using the indicated current sensor, a technique for recording high-current pulsed discharges of a plasma emitter in the mode of time profiling of the current pulse of two high-voltage capacitive storage devices with a total energy of up to 1800 kJ is realized. The discharge chamber, power supply circuits, and the formation of a plasma discharge are described. The design and principle of operation of a prototype of a two-pass polarimetric fiberoptic sensor with a Spun-type fiber and a Faraday compensator of mutual optical anisotropy are presented. The general scheme of current measurements, the sensor calibration scheme is presented, and the experience of using a prototype sensor for measuring high-power pulse currents is described. The features of the preliminary calibration of the sensor are discussed. The results of measuring the current by optical and traditional recording methods based on the Rogowski coil and Hall sensors are compared with each other, and a noticeable increase in the accuracy of reproducing the current pulse shape by the optical recording method is noted. Possible options for upgrading a fiber-optic sensor to expand the range of current recording are considered.

Crack monitoring using multiple smart materials; fiber-optic sensors & piezo sensors

ABSTRACTThis article focuses on health monitoring of structures using multiple smart materials. In this research, two fiber-optic sensors, namely fiber Bragg grating (FBG) and fiber-optic polarimetric sensor (FOPS), are investigated for damage detection in the beam specimen. FBG is used for local strain measurement while FOPS is used for global strain measurement. Both FBG and FOPS show significant changes in the strain due to damages in the specimen. Also, at the center of the specimen, piezoelectric wafer active sensor (PWAS) is attached. The electromechanical admittance (EMA) signature of the specimen beam is recorded by PWAS. The changes in the amplitudes of the peaks obtained at various frequencies in this EMA signature are analyzed, and it is shown that the peak amplitudes respond differently to damages and to change in loading. Thus, multiple smart materials (FBG, FOPS, and PWAS) are used to get improved information on the health of the beam.

Combined fiber Bragg grating and fiber optic polarimetric sensors on a single fiber for structural health monitoring of two-dimensional structures

Fiber optic sensors have a lot to offer in the field of structural health monitoring. The most widely investigated and implemented fiber optic sensors for structural health monitoring are fiber Bragg grating and fiber optic polarimetric sensor. Fiber Bragg grating sensors provide localized strain data, thereby providing local damage information, while fiber optic polarimetric sensors are known for their capabilities of global damage monitoring for both static and dynamic loadings. However, each sensor has to be used with its own instrumentation and processing system. In this article, it is shown that an fiber Bragg grating written on a polarizing maintaining fiber can discern information from both fiber Bragg grating and fiber optic polarimetric sensors using only one decoding system. This reduces costs and complexities. Furthermore, by proper multiplexing the polarizing maintaining-fiber Bragg grating sensor, it is possible to predict the damage location in plates. The results demonstrate that the damage site can be located in two-dimensional structures using this multiplexed sensing array.

Demodulation Algorithm Using the Hilbert Transform for a Dynamic Polarimetric Optical Fiber Sensor

A new method of signal analysis from a polarimetric optical fiber sensor is presented. The proposed method is based on the Hilbert transform and utilizes only one light detector to calculate a strain-induced phase shift, thereby overall sensor cost and complexity is minimized. The demodulation algorithm is optimized for the dynamic strain measurement used in composite materials monitoring. The method is implemented to measure the dynamic strain in a reflective sensor configuration. Vibration and mechanical impact measurements as well as Fourier analysis prove the reliability of the proposed method.

Distributed measurement of high electric current by means of polarimetric optical fiber sensor.

A novel distributed optical fiber sensor for spatially resolved monitoring of high direct electric current is proposed and analyzed. The sensor exploits Faraday rotation and is based on the polarization analysis of the Rayleigh backscattered light. Preliminary laboratory tests, performed on a section of electric cable for currents up to 2.5 kA, have confirmed the viability of the method.

FBG and FOPS for local and global structural health monitoring on a single fiber

Fiber Bragg grating (FBG) sensors and fiber optic polarimetric sensors (FOPS) have been widely researched and implemented for structural health monitoring (SHM). FBG essentially provides localized strain information, while FOPS gives a global indication of the structural health of materials. An FBG written on the polarization maintaining (PM) fiber can thus be used for both global structural monitoring and local strain sensing. However each sensor has to be used with its own hardware and processing. For gratings written on PM fibers two Bragg reflections, corresponding to two modes of polarization, are observed. While both Bragg wavelengths shift under longitudinal strain in unison, their relative peak amplitude does not change. In this paper, a novel concept is proposed which makes the peak amplitudes responsive to the longitudinal strain. This relative amplitude of both the peaks is used for the first time to determine the state of polarization (SOP) with no additional optical systems. With this additional information on SOP, PM–FBGs can be used for both, local and global SHM simultaneously. Further, a new design has been proposed which gives improved information on the damaged location in beam structures. This can be further extended to other complex geometries.

Efficient design of Fiber Optic Polarimetric Sensors for crack location and sizing

The Fiber Optic Polarimetric Sensor (FOPS) is an attractive tool for damage monitoring in structures. However the system is not capable of identifying damage location and crack size, which would further assist in the assessment of the severity of damage. Also, the output signal from FOPS is very noisy because of the fact that the whole fiber is sensitive and picks up unwanted signals from its surroundings. In the current work, a new design of FOPS has been put forward for structural health monitoring (SHM). It has been shown that in this new design, only the central part of FOPS is sensitive keeping the “leading-in” and “leading-out” parts insensitive, allowing SHM using FOPS sensitive only to the region of interest. This design is then implemented to locate and estimate the size of a crack in a cantilever. Unlike previous studies, the current approach considers second vibrational mode along with the first vibrational mode to get better understanding of the damage size and location. In this paper, the location and sizing of a crack in a cantilever beam are studied theoretically and verified experimentally. • A new design of Fiber Optic Parametric Sensor (FOPS) is presented for its application in structural health monitoring. • This new design enables FOPS to remote sensing and local health monitoring in the field of structural health monitoring. • A methodology is proposed for crack location and sizing with this design of FOPS in cantilevers.

Signal analysis of a polarimetric fiber optic sensor for dynamic strain monitoring

Polarimetric fiber optic sensors have many advantages over other fiber optic sensors and strain gauges. As opposed to Fiber Bragg Grating sensors, polarimetric fiber sensors can be constructed with very simple, portable and robust experimental setup. In the paper we propose two methods of the polarimetric sensor output signal analyzing. First method is based on depolarization phenomena, and calculates degree of polarization (DOP), second one uses Fast Fourier Transform to analyze dynamic sensor response. Usefulness of both methods has been shown and experimentally proven. Full Text: PDF References K. Schroeder, W. Ecke, J. Apitz, E. Lembke, G. Lenschow, "A fibre Bragg grating sensor system monitors operational load in a wind turbine rotor blade," Meas. Sci. Technol. 17, 1167–1172 (2006). CrossRef G. Hegde, A. Asundi, "Performance analysis of all-fiber polarimetric strain sensor for composites structural health monitoring," NDT&E International 39, 320–327 (2006). CrossRef G. Wehrle, P. Nohama, H. J. Kalinowski, P. I. Torres, L. C. G.Valente, "A fibre optic Bragg grating strain sensor for monitoring ventilatory movements" Meas. Sci. Technol. 12, 805–809 (2001). CrossRef W. J. Bock, A. W. Domanski, T. R. Wolinski, "Influence of High Hydrostatic Pressure on Beat Length in Highly Birefringent Single-Mode Bow-Tie Fibers," Appl. Optics 29, 3484-3488 (1990). CrossRef A. W. Domański, M. Bieda, P. Lesiak, P. Makowski, M. Szeląg, T. Poczęsny, K. Prokopczuk, P. Sobotka, M. Chychłowski, M. Sierakowski, T. R. Woliński, "Polarimetric optical fiber sensors for dynamic strain measurement in composite materials," Acta Physica Polonica A. 124, 399-401 (2013). CrossRef P. Lesiak, G. Rajan, Y. Semenova, G. Farrell, A. Boczkowska, A. W. Domański, T. R. Woliński, "A hybrid highly birefringent fiber optic sensing system for simultaneous strain and temperature measurement," PLP 3, 140-142 (2010). CrossRef R. A. Chipman, "Depolarization in the Mueller Calculus," Proc. SPIE 5158, 184–192 (2003). CrossRef N. Furstenau, M. Schmidt, W. J. Bock, W. Urbanczyk, "Dynamic pressure sensing with a fiber-optic polarimetric pressure transducer with two-wavelength passive quadrature readout," App. Opt. 37, 663-671 (1998). CrossRef

Polarization Mode Coupling Involved in a Capillary Optical Fiber Sensor: Modeling and Experimental Validation

Theoretical and experimental work is reported on a distributed polarimetric fiber optic sensor designed for application in capillary gas chromatography. The emphasis is made on the modeling of the polarization mode coupling mechanism in relation to the vapor zone distribution. Conditions are established to quantify the vapors' amount in the capillary from a Fourier analysis of the time-modulated optical signal. The model predicts an exponential temporal decay of the modulation amplitude for any initial vapor zone distribution at the injection and the quantification is related to the pre-exponential factor.

Influence of lamination process on optical fiber sensors embedded in composite material

In the paper we present the results of our research on optical fiber sensors embedded into composite material samples. We investigate the influence of the lamination process, axial orientation of an optical fiber sensor and coating of a fiber on stress monitoring of a composite material. In the paper we present two approaches to the case of composite condition monitoring, using a polarimetric fiber optic sensor as well as fiber Bragg gratings. We also present experimental evidence that interaction between a composite material and fiber optic sensors is very significant and depends on many factors such as fiber optic axial orientation and the coating layer surrounding an optical fiber.

Influence of Angular Orientation of the Embedded Highly Birefringent Fiber on PMD Changes under Axial Stress

In the paper we present results of the research on polarization mode dispersion changes inside the polarimetric optical fiber sensors based on highly birefringent optical fibers embedded into composite materials with different angular orientations of the optical axes. Based on measurements made for different types of highly birefringent optical fiber sensors we have shown that strain sensitivities after lamination process are different in comparison to the data obtained before lamination. Our results indicate that polarization mode dispersion in side-hole highly birefringent fibers under axial stress strongly depends on fiber orientation in the composite material suggesting that orientation of the polarization axes of the highly birefringent fiber can be responsible for behavior of the fiber inside the composite material.

Comparison of Bragg and Polarimetric Optical Fiber Sensors for Stress Monitoring in Composite Materials

Composite structures are made of two or more components with significantly different physical or chemicalpropertiesandtheyremainseparateanddistinctinamacroscopiclevelwithinthefinishedstructure. Thisfeatureallows for introducing optical fiber sensors into the composite material. These sensors can demonstrate stressdistributioninsidetestedmaterialinfluencedbyexternaltensions. Twotypesoftheopticalfibersensorsareusedas the 3D structure. One of them is based on application of fiber Bragg grating inside the core of the fiber.Longitudinal stress changes parameters of the Bragg grating and simultaneously, spectral characteristics of thelight transmitted through the fiber. The second one is based on application of highly birefringent fibers which,underexternalstress,introducepolarizationchangesoftheoutputlight.PACSnumbers:42.81.Gs,42.81.Pa,62.23.Pq

Single Polarization-Mode-Beating Frequency Fiber Laser

We demonstrate a single-frequency fiber laser cavity that allows for measuring changes in the relative phase of two independent orthogonal polarization modes. Longitudinal-mode selection is carried out by a matched-pair of fiber Bragg gratings in a Fabry-Perot configuration and an intracavity polarizing beam splitter allows for adjustments on each polarization independently. The polarization-mode-beating signals generated with this laser are stable over long periods of time, owing to the noise cancellation effect achieved by the common cavity shared by both polarizations. This heterodyne detection scheme allows for measuring changes in frequency as small as 5 kHz, or equivalently, wavelength changes of 40 am (attometers) which are practically impossible to resolve in the wavelength domain. The proposed configuration has possible significance as an ultrasensitive and stable polarimetric optical fiber sensor.

Design and development of a temperature-compensated fiber optic polarimetric pressure sensor based on photonic crystal fiber at 1550 nm

Use of photonic crystal fibers (PCFs) in the field of sensing is relatively new. We propose the application of a PCF for pressure sensing. The fiber analyzed is a polarization-maintaining PCF that has negligible sensitivity to temperature, making it an ideal candidate for pressure sensing in harsh environments. On the basis of theoretical and experimental analysis, PCF is proposed to be applied as a temperature-compensated pressure sensor. Detailed theoretical analysis and the experiment carried out are described to show the concept of the sensor.

Acoustic emission monitoring using a polarimetric Single Mode optical fibre sensor

Since the hydrocarbon reservoirs in Europe are rapidly depleting, there is a need for new 'intelligent' technology for the efficient commercial exploitation of the remaining hydrocarbon reservoirs: an intelligent and high-temperature, corrosion and fatigue resistant thermoplastic composite coiled tubing. This paper describes the polarimetric Fibre Optic Sensor and accompanying advanced transient signal detection techniques for an early detection of damage in this new type of intelligent composite tubing built for drilling and exploiting hydrocarbon reservoirs. The capabilities of the new optical system for detecting growing damage are demonstrated by carrying out bending tests on short test models of the tube.

Performance analysis of all-fiber polarimetric strain sensor for composites structural health monitoring

An improved design comprising a multifiber configuration for a polarimetric fiber optic sensor in real time structural health monitoring is presented in this paper. The sensor is in the form of a multifiber assembly composed of a high-birefringent (HiBi) sensing fiber and a single mode polarization maintaining (PM) fiber or a HiBi fiber as a lead-in and lead-out fiber, all spliced in sequence. The polarization behavior of the assembly is analyzed theoretically using Stokes matrix method for the monochromatic case. Based on this model a phase shift compensation method for multifiber sensors is proposed. The design also helps reduce the bulky optical component in the sensor. The static and dynamic responses of these multifiber sensors are experimentally evaluated to test the structural integrity of composites.