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Klaus Bohnert - One of the best experts on this subject based on the ideXlab platform.
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temperature compensation of interferometric and polarimetric Fiber optic current sensors with spun highly Birefringent Fiber
Journal of Lightwave Technology, 2019Co-Authors: Georg M Muller, Andreas Frank, Lin Yang, Klaus BohnertAbstract:We theoretically and experimentally investigate intrinsic temperature compensation of interferometric and polarimetric Fiber-optic current sensors with a coil of spun highly Birefringent Fiber operated in reflection mode. The interferometric sensor recovers the differential magneto-optic phase shift of the left- and right-handed circular (or slightly elliptical) polarization states in the Fiber by means of non-reciprocal phase modulation, whereas the polarimetric sensor employs a simple passive polarization analyzer. We show that the two sensor types exhibit substantial differences in their response to temperature changes. The main parameters that determine the sensors’ sensitivity to temperature are, besides the Fiber's Verdet constant, the intrinsic birefringence of the spun Fiber, the retardation of the Fiber retarder at the coil entrance that generates the elliptical polarization states, and the angle α between the principal axes of the retarder and spun Fiber. In particular, fringe contrast changes at varying Fiber birefringence make the polarimetric sensor version significantly more sensitive to temperature. Furthermore, whereas in the interferometric sensor, the contribution of the Fiber birefringence to the temperature dependence disappears for special Fiber orientations ( α = 0°, 90°), such an arrangement is not possible for the polarimetric sensor. Also, the response to changes in the retardation of the retarder shows different patterns for the two sensor types. In spite of the differences, we achieve intrinsic temperature compensation well within ±0.2% between –40 °C and 85 °C for both sensors by using the retarder contribution to balance the contributions from the Verdet constant, the Fiber birefringence, and potential further effects of temperature.
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inherent temperature compensation of Fiber optic current sensors employing spun highly Birefringent Fiber
Optics Express, 2016Co-Authors: Georg M Muller, Andreas Frank, Lin Yang, Klaus BohnertAbstract:We investigate the various contributions to the temperature dependence of an interferometric Fiber-optic current sensor employing spun highly-Birefringent sensing Fiber, in particular, the contributions from the Fiber retarder at the Fiber coil entrance, the spun Fiber's birefringence, and the Faraday effect. We theoretically and experimentally demonstrate that an appropriately designed retarder inherently compensates the temperature dependence of the Fiber birefringence and the Faraday effect. We demonstrate insensitivity to temperature to within ± 0.2% between -40 and + 85 °C. Furthermore, we analyze the influence of the retarder parameters on the linearity of the recovered magneto-optic phase shift vs. current and determine a set of parameters that results in a perfectly linear relationship.
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temperature and vibration insensitive Fiber optic current sensor
Journal of Lightwave Technology, 2002Co-Authors: Klaus Bohnert, Philippe Gabus, J Nehring, H BrandleAbstract:A robust interferometric Fiber-optic current sensor with inherent temperature compensation of the Faraday effect is presented. Sensor configurations based on Sagnac and polarization-rotated reflection interferometers are considered. The sensing Fiber is residing and thermally annealed in a coiled capillary of fused silica. The capillary is embedded in silicone within a ring-shaped housing. It is theoretically and experimentally shown that the temperature dependence of the Birefringent Fiber-optic phase retarders of the interferometers can be employed to balance the temperature dependence of the Faraday effect (0.7/spl times/10/sup -4///spl deg/C). Insensitivity of the sensor to temperature within 0.2% is demonstrated between -35/spl deg/C and 85/spl deg/C. The influence of the phase retarders on the linearity of the sensor is also addressed. Furthermore, the sensitivity to vibration of the two configurations at frequencies up to 500 Hz and accelerations up to 10 g is compared. High immunity of the reflective sensor to mechanical perturbations is verified.
J L Santos - One of the best experts on this subject based on the ideXlab platform.
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a novel highly Birefringent Fiber loop mirror sensor based on a 3 3 coupler
Proceedings of SPIE, 2012Co-Authors: Ricardo M Silva, J L Santos, A Lobo B Ribeiro, O FrazaoAbstract:In this work, a novel high Birefringent (HiBi) Fiber loop mirror sensor based on a "figure-of-eight" constructed with a 3×3 Fiber coupler, is presented. The "figure-of-eight" is formed by two Fiber loop mirrors (FLM's) made by four of the six Fiber arms of the 3×3 Fiber coupler. The other two remaining Fiber ports of the 3×3 coupler are used as input and output Fibers of the compound sensor. The sensing head is located in the one of the FLM and it is formed by a spliced section of HiBi elliptical core Fiber. The spectral response of this "figure-of-eight" configuration presents two interference optical signals that can be easily tuned by a polarization controller that is located in the other FLM, and which is made only of standard singlemode Fiber from two arms of the 3×3 coupler. The sensor head was optically characterized both in temperature and strain, showing wavelength dependence sensitivities of -0.23 nm/°C and - 2.6 pm/μe, for temperature and strain, respectively. It is noticed that these sensitivities are practically the same for the two interference signals. Future work will explore the possibility to use the singlemode FLM to interrogate the sensor head made by HiBi Fiber section, and providing elimination of phase fluctuations that can occur, increasing its potential for remote sensing applications.
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high Birefringent Fiber loop mirror sensors with an output port probe
IEEE Photonics Technology Letters, 2011Co-Authors: O Frazao, Ricardo M Silva, J L SantosAbstract:Two new configurations of high-Birefringent Fiber loop mirror with an output port probe are proposed. The two configurations used two couplers spliced between them with unbalanced arms and one output port is used as the probe sensor. The difference between them is that the section length of high-Birefringent Fiber is located between the two couplers (first new configuration) or spliced in the output port probe (second new configuration). The second new configuration presents great advantage, especially for remote sensing using only one Fiber to the sensing head. The two new configurations were compared with the conventional high-Birefringent Fiber loop mirror when strain is applied and showed similar sensitivities. The first new configuration is studied as an optical refractometer.
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sensing characteristics of long period gratings and rocking filters based on highly Birefringent boron doped photonic crystal Fiber and fabricated by a co 2 laser
Proceedings of SPIE, 2010Co-Authors: J P Carvalho, Gabriela Statkiewiczbarabach, Alicja Anuszkiewicz, Jan Wojcik, O Frazao, J M Baptista, J L Santos, Waclaw UrbanczykAbstract:ABSTRACT In this work, we demonstrate the possibility of fabricating sh ort LPGs and rocking filters in highly Birefringent Photonic Crystal Fiber using CO 2 laser. In our experiments both kinds of gratings were made in the same Boron doped highly Birefringent PCF using similar exposure parameters. We also present the sensing capabilities of both fabricated gratings to temperature, strain and hydrostatic pressure by interroga tion of the wavelength shifts at the different resonances. Keywords: Hi-Bi PCF, CO 2 laser, long period grating, rocking filter. 1. INTRODUCTION Long-period gratings (LPG) [1-4] are structures which consist of a large-scale (typically 100 µm to 10 mm) periodic axial perturbation in the refractive index of the core or in geom etry of the Fiber. The effect of this modulation is coupling of light from the fundamental core mode to the co-propagating cladding modes at discrete wavelengths defined by the phase matching condition. As the excited cladding modes are ty pically highly attenuated, it results in the appearance of a selective resonance loss in the transmi ssion spectrum of the fundamental mode. Th e shape of the opti cal spectrum, with several wavelength attenuation bands, is sensitive to the fibre design, LPG period and length, and to the local environment: temperature, strain, bend radius and also to the refractive index of the surrounding medium [5]. Changes in such parameters can modify the LPG period and/or the differential refractive index of the core and cladding modes. As consequence the phase matching condition is modified for coup ling to the cladding modes, which results in a change in the wavelength peak of the attenuation bands. For the LPGs written in the photonic crystal fibres (PCFs), due to its particular design, different behaviours could be observed. For example it was noticed that this kind of structures presents very low sensitivity to temperature [6]. An optical Fiber rocking filter is a special type of the long period grating, which resonantly couples the fundamental polarization modes launched in the principal axes of a Birefringent Fiber [7]. Typically, the coupling effect is achieved by periodic mechanical twist of the Birefringent Fiber. If the distance between successive twist points equals the Fiber beat length, resonant coupling between orthogonally polarized modes occurs. In the sensing field, similarly to what happens with LPGs, rocking filters have prov ed to be effective sensing elements of different measurands [8,9].
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Fiber optic interferometric torsion sensor based on a two lp mode operation in Birefringent Fiber
IEEE Photonics Technology Letters, 2009Co-Authors: O Frazao, C Jesus, J M Baptista, J L Santos, P RoyAbstract:A Fiber-optic sensor for torsion measurement, based on a two-linearly polarized (LP)-mode operation in ultrahigh Birefringent photonic crystal Fiber is described. The structure of the photonic crystal Fiber presents two large asymmetric holes adjacent to the core Fiber. When linearly polarized light is injected in x - and y -directions, respectively, two separate interferometers can be obtained. In one of these cases, as torsion is applied to the sensing head a beat between the two interferometers is formed due to the simultaneous excitation of the two polarization states. The detection technique to read the torsion sensor is based on the analysis of the fast Fourier transform, which proved to be an effective and simple solution. The sensor exhibited reduced sensitivity to temperature.
O Frazao - One of the best experts on this subject based on the ideXlab platform.
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a novel highly Birefringent Fiber loop mirror sensor based on a 3 3 coupler
Proceedings of SPIE, 2012Co-Authors: Ricardo M Silva, J L Santos, A Lobo B Ribeiro, O FrazaoAbstract:In this work, a novel high Birefringent (HiBi) Fiber loop mirror sensor based on a "figure-of-eight" constructed with a 3×3 Fiber coupler, is presented. The "figure-of-eight" is formed by two Fiber loop mirrors (FLM's) made by four of the six Fiber arms of the 3×3 Fiber coupler. The other two remaining Fiber ports of the 3×3 coupler are used as input and output Fibers of the compound sensor. The sensing head is located in the one of the FLM and it is formed by a spliced section of HiBi elliptical core Fiber. The spectral response of this "figure-of-eight" configuration presents two interference optical signals that can be easily tuned by a polarization controller that is located in the other FLM, and which is made only of standard singlemode Fiber from two arms of the 3×3 coupler. The sensor head was optically characterized both in temperature and strain, showing wavelength dependence sensitivities of -0.23 nm/°C and - 2.6 pm/μe, for temperature and strain, respectively. It is noticed that these sensitivities are practically the same for the two interference signals. Future work will explore the possibility to use the singlemode FLM to interrogate the sensor head made by HiBi Fiber section, and providing elimination of phase fluctuations that can occur, increasing its potential for remote sensing applications.
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high Birefringent Fiber loop mirror sensors with an output port probe
IEEE Photonics Technology Letters, 2011Co-Authors: O Frazao, Ricardo M Silva, J L SantosAbstract:Two new configurations of high-Birefringent Fiber loop mirror with an output port probe are proposed. The two configurations used two couplers spliced between them with unbalanced arms and one output port is used as the probe sensor. The difference between them is that the section length of high-Birefringent Fiber is located between the two couplers (first new configuration) or spliced in the output port probe (second new configuration). The second new configuration presents great advantage, especially for remote sensing using only one Fiber to the sensing head. The two new configurations were compared with the conventional high-Birefringent Fiber loop mirror when strain is applied and showed similar sensitivities. The first new configuration is studied as an optical refractometer.
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sensing characteristics of long period gratings and rocking filters based on highly Birefringent boron doped photonic crystal Fiber and fabricated by a co 2 laser
Proceedings of SPIE, 2010Co-Authors: J P Carvalho, Gabriela Statkiewiczbarabach, Alicja Anuszkiewicz, Jan Wojcik, O Frazao, J M Baptista, J L Santos, Waclaw UrbanczykAbstract:ABSTRACT In this work, we demonstrate the possibility of fabricating sh ort LPGs and rocking filters in highly Birefringent Photonic Crystal Fiber using CO 2 laser. In our experiments both kinds of gratings were made in the same Boron doped highly Birefringent PCF using similar exposure parameters. We also present the sensing capabilities of both fabricated gratings to temperature, strain and hydrostatic pressure by interroga tion of the wavelength shifts at the different resonances. Keywords: Hi-Bi PCF, CO 2 laser, long period grating, rocking filter. 1. INTRODUCTION Long-period gratings (LPG) [1-4] are structures which consist of a large-scale (typically 100 µm to 10 mm) periodic axial perturbation in the refractive index of the core or in geom etry of the Fiber. The effect of this modulation is coupling of light from the fundamental core mode to the co-propagating cladding modes at discrete wavelengths defined by the phase matching condition. As the excited cladding modes are ty pically highly attenuated, it results in the appearance of a selective resonance loss in the transmi ssion spectrum of the fundamental mode. Th e shape of the opti cal spectrum, with several wavelength attenuation bands, is sensitive to the fibre design, LPG period and length, and to the local environment: temperature, strain, bend radius and also to the refractive index of the surrounding medium [5]. Changes in such parameters can modify the LPG period and/or the differential refractive index of the core and cladding modes. As consequence the phase matching condition is modified for coup ling to the cladding modes, which results in a change in the wavelength peak of the attenuation bands. For the LPGs written in the photonic crystal fibres (PCFs), due to its particular design, different behaviours could be observed. For example it was noticed that this kind of structures presents very low sensitivity to temperature [6]. An optical Fiber rocking filter is a special type of the long period grating, which resonantly couples the fundamental polarization modes launched in the principal axes of a Birefringent Fiber [7]. Typically, the coupling effect is achieved by periodic mechanical twist of the Birefringent Fiber. If the distance between successive twist points equals the Fiber beat length, resonant coupling between orthogonally polarized modes occurs. In the sensing field, similarly to what happens with LPGs, rocking filters have prov ed to be effective sensing elements of different measurands [8,9].
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Fiber optic interferometric torsion sensor based on a two lp mode operation in Birefringent Fiber
IEEE Photonics Technology Letters, 2009Co-Authors: O Frazao, C Jesus, J M Baptista, J L Santos, P RoyAbstract:A Fiber-optic sensor for torsion measurement, based on a two-linearly polarized (LP)-mode operation in ultrahigh Birefringent photonic crystal Fiber is described. The structure of the photonic crystal Fiber presents two large asymmetric holes adjacent to the core Fiber. When linearly polarized light is injected in x - and y -directions, respectively, two separate interferometers can be obtained. In one of these cases, as torsion is applied to the sensing head a beat between the two interferometers is formed due to the simultaneous excitation of the two polarization states. The detection technique to read the torsion sensor is based on the analysis of the fast Fourier transform, which proved to be an effective and simple solution. The sensor exhibited reduced sensitivity to temperature.
P A S Jorge - One of the best experts on this subject based on the ideXlab platform.
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simultaneous measurement of refractive index and temperature using multimode interference inside a high birefringence Fiber loop mirror
Sensors and Actuators B-chemical, 2013Co-Authors: Carlos Gouveia, J M Baptista, Giancarlo Chesini, Cristiano M B Cordeiro, P A S JorgeAbstract:Abstract A Fiber optic sensor for simultaneous measurement of refractive index and temperature is presented. The sensing probe is realized by introducing a multimode interference device inside a high birefringence Fiber loop mirror resulting in a configuration capable of refractive index and temperature discrimination. The multimode interference peak is sensitive to the surrounding refractive index (90 nm/RIU) and slightly responsive to the temperature (0.01 nm/°C). On the other hand, the Birefringent Fiber loop mirror is highly sensitive to temperature (2.36 nm/°C) and it has almost no response to refractive index. Using a power ratiometric peak detection scheme, a temperature independent refractive index measurement can be achieved with a resolution of ±2.25 × 10−5 RIU.
Waclaw Urbanczyk - One of the best experts on this subject based on the ideXlab platform.
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sensitivity of Birefringent microstructured polymer optical Fiber to hydrostatic pressure
IEEE Photonics Technology Letters, 2013Co-Authors: Tadeusz Martynkien, Pawel Mergo, Waclaw UrbanczykAbstract:We present a PMMA Birefringent Fiber with enhanced polarimetric sensitivity to hydrostatic pressure, obtained by enlarging selected holes in the microstructured cladding. The Fiber shows a linear response to pressure with small hysteresis in the pressure range up to 8.5 MPa and the sensitivity of 48 ${\rm rad}/{\rm MPa}\cdot{\rm m}$ at 600 nm. The average temperature sensitivity measured in the range 22–40 $^{\circ}{\rm C}$ is 1 ${\rm rad}/{\rm K}\cdot{\rm m}$ at 600 nm. The Fiber, however, shows significant hysteresis increasing with the temperature range. We also present the results of numerical simulations of the birefringence and the sensitivity to pressure. The contribution of stress and deformation effects to the overall pressure sensitivity in the investigated PMMA Fiber and the silica Fiber of the same geometry is compared. This allows us to explain different signs of pressure sensitivity observed in silica and the PMMA Fibers.
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sensing characteristics of long period gratings and rocking filters based on highly Birefringent boron doped photonic crystal Fiber and fabricated by a co 2 laser
Proceedings of SPIE, 2010Co-Authors: J P Carvalho, Gabriela Statkiewiczbarabach, Alicja Anuszkiewicz, Jan Wojcik, O Frazao, J M Baptista, J L Santos, Waclaw UrbanczykAbstract:ABSTRACT In this work, we demonstrate the possibility of fabricating sh ort LPGs and rocking filters in highly Birefringent Photonic Crystal Fiber using CO 2 laser. In our experiments both kinds of gratings were made in the same Boron doped highly Birefringent PCF using similar exposure parameters. We also present the sensing capabilities of both fabricated gratings to temperature, strain and hydrostatic pressure by interroga tion of the wavelength shifts at the different resonances. Keywords: Hi-Bi PCF, CO 2 laser, long period grating, rocking filter. 1. INTRODUCTION Long-period gratings (LPG) [1-4] are structures which consist of a large-scale (typically 100 µm to 10 mm) periodic axial perturbation in the refractive index of the core or in geom etry of the Fiber. The effect of this modulation is coupling of light from the fundamental core mode to the co-propagating cladding modes at discrete wavelengths defined by the phase matching condition. As the excited cladding modes are ty pically highly attenuated, it results in the appearance of a selective resonance loss in the transmi ssion spectrum of the fundamental mode. Th e shape of the opti cal spectrum, with several wavelength attenuation bands, is sensitive to the fibre design, LPG period and length, and to the local environment: temperature, strain, bend radius and also to the refractive index of the surrounding medium [5]. Changes in such parameters can modify the LPG period and/or the differential refractive index of the core and cladding modes. As consequence the phase matching condition is modified for coup ling to the cladding modes, which results in a change in the wavelength peak of the attenuation bands. For the LPGs written in the photonic crystal fibres (PCFs), due to its particular design, different behaviours could be observed. For example it was noticed that this kind of structures presents very low sensitivity to temperature [6]. An optical Fiber rocking filter is a special type of the long period grating, which resonantly couples the fundamental polarization modes launched in the principal axes of a Birefringent Fiber [7]. Typically, the coupling effect is achieved by periodic mechanical twist of the Birefringent Fiber. If the distance between successive twist points equals the Fiber beat length, resonant coupling between orthogonally polarized modes occurs. In the sensing field, similarly to what happens with LPGs, rocking filters have prov ed to be effective sensing elements of different measurands [8,9].
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sensing characteristics of rocking filters fabricated in microstructured Birefringent Fibers
European Quantum Electronics Conference, 2009Co-Authors: Gabriela Statkiewiczbarabach, Alicja Anuszkiewicz, Waclaw Urbanczyk, Kamil Durakiewicz, Jan WojcikAbstract:A rocking filter is a type of long period grating that rotates azimuth of a linearly polarized light launched into one polarization mode of a Birefringent Fiber. If the grating period equals a beat length of the Birefringent Fiber (l=L B ), a resonant coupling between the modes of orthogonal polarization arises [1]. In this paper, we demonstrate that in microstructured Fibers (MSFs) the phase matching condition between polarization modes can be obtained simultaneously at several wavelengths, because the phase birefringence in MSFs is very dispersive and increases against wavelength [2]. In Fig. 1b, we show the transmission characteristic for the excited polarization mode registered for the rocking filter fabricated in highly Birefringent MSF consisting of 13 coupling points with a period of Λ=8 mm. The measured positions of respective resonances arising at 855, 1271 and 1623 nm are in good agreement with the calculated values obtained using Jones matrix formalism.
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rocking filters fabricated in Birefringent photonic crystal Fiber
16th Polish-Slovak-Czech Optical Conference on Wave and Quantum Aspects of Contemporary Optics, 2008Co-Authors: Gabriela Statkiewiczbarabach, Alicja Anuszkiewicz, Waclaw Urbanczyk, Jan WojcikAbstract:We demonstrate an efficient higher order rocking filter, which resonantly couples polarization modes guided in Birefringent photonic crystal Fibers. The grating was inscribed in the Birefringent Fiber with two large holes adjacent to the core by periodic mechanical twisting and heating with an arc fusion splicer. Because in photonic crystal Fibers the phase birefringence is very dispersive and increases against wavelength, the phase matching between coupled modes can be obtained simultaneously at several wavelengths. In particular, we demonstrate that for the grating period / =8 mm, resonant coupling can be obtained at three different wavelengths. The first order coupling (–13dB) is obtained for �� = LB . This condition is fulfilled at O= 856 nm. The second order coupling (–20dB) is obtained for �� = 2LB at O=1270 nm and the third
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sensing characteristics of rocking filter fabricated in microstructured Birefringent Fiber using fusion arc splicer
Optics Express, 2008Co-Authors: Gabriela Statkiewiczbarabach, Alicja Anuszkiewicz, Waclaw Urbanczyk, Jan WojcikAbstract:We demonstrate that higher order rocking filters coupling energy between polarization modes at several wavelengths can be fabricated in a Birefringent photonic crystal Fiber using a fusion arc splicer. Three resonant couplings were identified, respectively at 855, 1271, and 1623 nm for the filter with a pitch distance of 8 mm characterized in this work. We also measured the filter response to temperature, elongation and hydrostatic pressure at the first and the second resonance. Our results show that the fabricated filter has very low sensitivity to temperature 1.77 and 1.38 pm/K, moderate sensitivity to elongation 1.35 and 1.12 nm/mstrain, and extremely high sensitivity to hydrostatic pressure 6.14 and 3.30 nm/MPa, respectively at the first and the second resonance.