基于旋转折变型长周期光纤光栅对的高分辨率扭曲传感器

A torsion sensor with high resolution based on a pair of long-period fiber gratings with rotary refractive index modulation

报道了一种基于光纤环形激光器和旋转折变型长周期光纤光栅(R-LPFG)对的高分辨率扭曲传感器。激光器的环形腔中包含由一对相同R-LPFG)形成的Mach-Zehnder干涉仪(MZI)。R-LPFG是利用CO2激光器在扭曲单模光纤(SMF)上写入的,通过激光器输出波长的漂移量及漂移方向可以实现对施加在MZI上的扭曲量和扭曲方向的同时测量。由于激光器的输出具有线宽窄和对比度高的优点,因此本文的扭曲传感器比普通的无源扭曲传感器测量更加精确。该扭曲传感器在±100rad/m范围内的灵敏度为0.084nm/(rad/m);当光谱仪(OSA)的分辨率为10pm时,传感器的扭曲分辨率可达0.12rad/m。

We experimentally demonstrate a fiber ring laser for high-resolution torsion measurement, where the laser cavity has a Mach-Zehnder interferometer formed by a pair of longperiod fiber gratings written in a twisted single-mode fiber by a CO2 laser. The emitting wavelength of the laser provides a measure of the torsion rate applied to the grating pair, while the direction of the wavelength shift indicates the direction of the applied torsion. The narrow linewidth and the large side-mode suppression ratio of the laser can provide a much more precise measurement of torsion compared with the passive fiber-optic torsion sensors. The achieved torsion sensitivity is 0, 084 nm/（rad/m） in the torsion range of -± 100 rad/m, which corresponds to a torsion resolution of 0. 12 rad/m, for the wavelength resolution of the optical spectrum analyzer used in our experiments is -10 pm.