One method based on the end-face reflection as a reference was used to measure weak grating reflectivity of 0.01%-1%. For measuring ultra-weak grating reflectivity, the grating group with an identical wavelength was u...One method based on the end-face reflection as a reference was used to measure weak grating reflectivity of 0.01%-1%. For measuring ultra-weak grating reflectivity, the grating group with an identical wavelength was used. By using anhydrous alcohol and deionized water as the reflecting medium, the single- pulse FBG reflectivity of a highly doped-Ge photosensitive fiber was calculated to be about 0.747% and 0.739%, respectively; and the single-pulse FBG reflectivity of ordinary SMF fiber was about 0.016% and 0.015%, respectively. The consistent results by the two different reflecting media showed that the end-face reflection method on the grating group was feasible.展开更多
The influence of the circular birefringence on the measurement performance was analyzed based on the Polarization Properties of FBG in this paper. Due to the circular birefringence, the linear relationship between the...The influence of the circular birefringence on the measurement performance was analyzed based on the Polarization Properties of FBG in this paper. Due to the circular birefringence, the linear relationship between the max of PDL and pressure has been broken down. To estimate the cross sensitivity, a new parameter named relative peak of PDL (RPPDL) is proposed. Under different circular birefringence, the same pressure sensitivity of sensor has been achieved. The theo- retical analysis and experiment results prove that transverse strain sensor of FBG is insensitive to the circular birefrin- gence by applying the RPPDL. This research can be provided to useful and practical application.展开更多
为提高超弱光纤光栅反射信号光电检测电路的测量精度,提出一种新的变步长LMS算法去除光电探测器信号中的高斯噪声。针对基于对数函数的变步长LMS(Least Mean Square)算法其步长因子易受噪声干扰,导致其步长因子取值在最优解附近波动的...为提高超弱光纤光栅反射信号光电检测电路的测量精度,提出一种新的变步长LMS算法去除光电探测器信号中的高斯噪声。针对基于对数函数的变步长LMS(Least Mean Square)算法其步长因子易受噪声干扰,导致其步长因子取值在最优解附近波动的问题。根据高斯白噪声相关性差的特性,使用相关特性改进步长因子的更新公式,降低不相关噪声对稳态误差的影响。通过理论分析和MATLAB软件仿真结果对比分析改进前后收敛速度和稳态误差,本算法在低信噪比条件下稳态误差减小三分之一,收敛速度更快,具有更好的抗噪、滤波性能,有效抑制了超弱光纤光栅反射信号检测的噪声。展开更多
基金Funded by the National Natural Science Foundation of China (Nos.61205070 and 61290311)
文摘One method based on the end-face reflection as a reference was used to measure weak grating reflectivity of 0.01%-1%. For measuring ultra-weak grating reflectivity, the grating group with an identical wavelength was used. By using anhydrous alcohol and deionized water as the reflecting medium, the single- pulse FBG reflectivity of a highly doped-Ge photosensitive fiber was calculated to be about 0.747% and 0.739%, respectively; and the single-pulse FBG reflectivity of ordinary SMF fiber was about 0.016% and 0.015%, respectively. The consistent results by the two different reflecting media showed that the end-face reflection method on the grating group was feasible.
文摘The influence of the circular birefringence on the measurement performance was analyzed based on the Polarization Properties of FBG in this paper. Due to the circular birefringence, the linear relationship between the max of PDL and pressure has been broken down. To estimate the cross sensitivity, a new parameter named relative peak of PDL (RPPDL) is proposed. Under different circular birefringence, the same pressure sensitivity of sensor has been achieved. The theo- retical analysis and experiment results prove that transverse strain sensor of FBG is insensitive to the circular birefrin- gence by applying the RPPDL. This research can be provided to useful and practical application.
文摘为提高超弱光纤光栅反射信号光电检测电路的测量精度,提出一种新的变步长LMS算法去除光电探测器信号中的高斯噪声。针对基于对数函数的变步长LMS(Least Mean Square)算法其步长因子易受噪声干扰,导致其步长因子取值在最优解附近波动的问题。根据高斯白噪声相关性差的特性,使用相关特性改进步长因子的更新公式,降低不相关噪声对稳态误差的影响。通过理论分析和MATLAB软件仿真结果对比分析改进前后收敛速度和稳态误差,本算法在低信噪比条件下稳态误差减小三分之一,收敛速度更快,具有更好的抗噪、滤波性能,有效抑制了超弱光纤光栅反射信号检测的噪声。
基金This work was supported by the Major Program of the National Natural Science Foundation of China, NSFC （Grant No. 61290311） and the Natural Science Foundation of Hubei Province, China （No. 2014CFB269）.
