In this work wavelength sensitivity in mechanically induced long period fiber gratings (MLPFG) is analyzed. This analysis is first carried out both in standard single-mode fiber SMF-28 and in Er-doped fibers. The mech...In this work wavelength sensitivity in mechanically induced long period fiber gratings (MLPFG) is analyzed. This analysis is first carried out both in standard single-mode fiber SMF-28 and in Er-doped fibers. The mechanical analysis for both types of fibers under different torsion conditions is presented. In order to apply the torsion one of the fiber ends is fixed while torsion is applied on the other end. A MLPFG whose period is 503 μm is used to press the fiber after torsion is applied. This allows for micro curvatures to be formed on the fiber, which in turn generates a periodical index perturbation on it. Here, it was noted that the sensitive wavelength shift of the rejection bands is bigger for Er-doped fibers. For a torsion of 6 turns applied to 10 cm of doped fiber the wavelength peaks can be moved up to 25 nm, which is longer to what was detected on standard fibers. Therefore, by using Er-doped fibers to monitor torsion on structures will give more sensitive and accurate results than using standard fibers. These results can be employed for sensing applications, especially for small to medium size structures, which can be mechanical, civil or aeronautics.展开更多
We propose a high-sensitivity bidirectional torsion sensor using a helical seven-core fiber taper embedded in multimode fiber(MHSTM).Sensors with different taper waists and helical pitches are fabricated,and their tra...We propose a high-sensitivity bidirectional torsion sensor using a helical seven-core fiber taper embedded in multimode fiber(MHSTM).Sensors with different taper waists and helical pitches are fabricated,and their transmission spectra are obtained and analyzed.The waist and length of the sandwiched seven-core fiber are finally determined to be 68 μm and3 mm,respectively.The experimental results show that the clockwise and counterclockwise torsion sensitivities of the proposed sensor are 2.253 nm/(rad/m) and-1.123 nm/(rad/m),respectively.When tapered waist diameter reduces to48 μm,a superior torsion sensitivity of 5.391 nm/(rad/m) in the range of 0-4.24 nm/(rad/m) is obtained,which is 46 times as large as the traditional helical seven-core fiber structure.In addition,the MHSTM structure is also relatively stable to temperature variations.展开更多
We propose and investigate a compact optical fiber sensor that aims to measure the torsion in both amount and direction with high sensitivity.This sensor is configured by a triangular-prism-shaped long-period fiber gr...We propose and investigate a compact optical fiber sensor that aims to measure the torsion in both amount and direction with high sensitivity.This sensor is configured by a triangular-prism-shaped long-period fiber grating,which is fabricated by the high frequency CO_(2) laser polished method.The unique design of the triangular-shaped structure breaks the rotational symmetry of the optical fiber and provides high sensitivity for torsion measurement.In preliminary experiments,the torsion response of the sensor achieves a good stability and linearity.The torsion sensitivity is 0.54 nm/(rad/m),which renders the proposed structure a highly sensitive torsion sensor.展开更多
A torsion sensor based on the near-helical（NH） long period fiber grating（LPFG） is fabricated by using a high frequency pulsed CO2 laser. Each groove of the NH-LPFG is spirally written in the four sides of a single...A torsion sensor based on the near-helical（NH） long period fiber grating（LPFG） is fabricated by using a high frequency pulsed CO2 laser. Each groove of the NH-LPFG is spirally written in the four sides of a single-mode fiber. The NH-LPFG has a helical periodic vertical index modulation. This is different from the screw-type index modulation of the common helical LPFGs（H-LPFGs） fabricated in a twisted fiber. The torsion and temperature characteristics of the NH-LPFG are experimentally investigated. The temperature sensitivity is about0.0668 nm/℃. The torsion sensitivity is 0.103 nm/（rad/m） and independent of the polarization state of incident light.展开更多
文摘In this work wavelength sensitivity in mechanically induced long period fiber gratings (MLPFG) is analyzed. This analysis is first carried out both in standard single-mode fiber SMF-28 and in Er-doped fibers. The mechanical analysis for both types of fibers under different torsion conditions is presented. In order to apply the torsion one of the fiber ends is fixed while torsion is applied on the other end. A MLPFG whose period is 503 μm is used to press the fiber after torsion is applied. This allows for micro curvatures to be formed on the fiber, which in turn generates a periodical index perturbation on it. Here, it was noted that the sensitive wavelength shift of the rejection bands is bigger for Er-doped fibers. For a torsion of 6 turns applied to 10 cm of doped fiber the wavelength peaks can be moved up to 25 nm, which is longer to what was detected on standard fibers. Therefore, by using Er-doped fibers to monitor torsion on structures will give more sensitive and accurate results than using standard fibers. These results can be employed for sensing applications, especially for small to medium size structures, which can be mechanical, civil or aeronautics.
基金supported in part by the Joint Research Fund in Astronomy under Cooperative Agreement between the National Natural Science Foundation of China(NSFC) and the Chinese Academy of Sciences(CAS)(Nos.U2031132 and U2031130)the National Natural Science Foundation of China(No.12103015)the Fundamental Research Funds for the Central Universities to the Harbin Engineering University。
文摘We propose a high-sensitivity bidirectional torsion sensor using a helical seven-core fiber taper embedded in multimode fiber(MHSTM).Sensors with different taper waists and helical pitches are fabricated,and their transmission spectra are obtained and analyzed.The waist and length of the sandwiched seven-core fiber are finally determined to be 68 μm and3 mm,respectively.The experimental results show that the clockwise and counterclockwise torsion sensitivities of the proposed sensor are 2.253 nm/(rad/m) and-1.123 nm/(rad/m),respectively.When tapered waist diameter reduces to48 μm,a superior torsion sensitivity of 5.391 nm/(rad/m) in the range of 0-4.24 nm/(rad/m) is obtained,which is 46 times as large as the traditional helical seven-core fiber structure.In addition,the MHSTM structure is also relatively stable to temperature variations.
基金supported by the Joint Research Fund in Astronomy under cooperative agreement between the National Natural Science Foundation of China(NSFC)and Chinese Academy of Sciences(CAS)(Nos.U1831115,U1631239,and U1931206)the Dean Project of Guangxi Key Laboratory of Wireless Broadband Communication and Signal Processing(No.GXKL06190106)the Key Projects of Natural Science Foundation of Heilongjiang Province(No.ZD2019H003)。
文摘We propose and investigate a compact optical fiber sensor that aims to measure the torsion in both amount and direction with high sensitivity.This sensor is configured by a triangular-prism-shaped long-period fiber grating,which is fabricated by the high frequency CO_(2) laser polished method.The unique design of the triangular-shaped structure breaks the rotational symmetry of the optical fiber and provides high sensitivity for torsion measurement.In preliminary experiments,the torsion response of the sensor achieves a good stability and linearity.The torsion sensitivity is 0.54 nm/(rad/m),which renders the proposed structure a highly sensitive torsion sensor.
基金supported by the National Natural Science Foundation of China(Nos.61377084,41174161,and 61775044)the Joint Research Fund in Astronomy(No.U1631239)under cooperative agreement between the National Natural Science Foundation of China(NSFC)and the Chinese Academy of Sciences(CAS)in part by the Aeronautical Science Foundation of China(No.201608P6003)
文摘A torsion sensor based on the near-helical（NH） long period fiber grating（LPFG） is fabricated by using a high frequency pulsed CO2 laser. Each groove of the NH-LPFG is spirally written in the four sides of a single-mode fiber. The NH-LPFG has a helical periodic vertical index modulation. This is different from the screw-type index modulation of the common helical LPFGs（H-LPFGs） fabricated in a twisted fiber. The torsion and temperature characteristics of the NH-LPFG are experimentally investigated. The temperature sensitivity is about0.0668 nm/℃. The torsion sensitivity is 0.103 nm/（rad/m） and independent of the polarization state of incident light.
