同时测量扭转角度和扭转方向的侧漏光子晶体光纤扭转传感器

基于所研制的侧漏型光子晶体光纤,提出并构建了出一种同时检测扭转角度 和扭转方向的高灵敏度Sagnac干涉仪型光纤扭转传感器.顺时针扭转时, 传感器传输谱向短波长方向偏移;逆时针扭转,向长波长方向偏移. 对传感器扭转特性的实验研究结果表明,构成Sagnac干涉仪的侧漏型光子晶体光纤的长度, 对扭转敏感系数和扭转角度测量范围起着决定性作用.当光纤长度较短时, 扭转传感器具有较大的扭转灵敏度,但扭转角度测量范围较小;光纤长度增加时,扭转灵敏度减小, 扭转角度测量范围增大.当构成Sagnac干涉仪的侧漏型光子晶体光纤长度为14.85 cm时, 传感器的扭转敏感系数可达到0.9354 nm/(°),扭转角度测量范围为-90°—90°; 光纤长度为32 cm时,最大扭转敏感系数降为0.2132 nm/(°), 扭转角度测量范围扩展至-180°—180°. 采用二维测量矩阵法可以有效排除温度对扭转角度的测量的影响. 关键词： 光纤传感器 侧漏型光子晶体光纤 扭转传感器 Sagnac干涉仪

A side-leakage photonic crystal fiber torsion sensor for measuring torsion angle and determining torsion direction simultaneously

A highly sensitive torsion sensor, which can measure the torsion angle and determine the torsion direction simultaneously, is proposed and experimentally demonstrated by using side-leakage photonic crystal fiber (SLPCF) based Sagnac loop. When the SLPCF is turned in the clockwise direction, the transmission spectra of the torsion sensor shift towards the shorter wavelength side; whereas the transmission spectra of the torsion sensor shift towards the longer wavelength side when the SLPCF is turned in anticlockwise direction. Experimental results demonstrate that the length of the SLPCF inserted into Sagnac loop plays an important role for determining the torsion sensitivity and the torsion angle range. For the SLPCF with shorter length, the torsion sensor has the larger torsion sensitivity, but the torsion angle measuring range would be decreased. The opposite situation takes place for the SLPCF with longer length used in the torsion sensor. When the length of SLPCF is 14.85 cm, the torsion sensitivity of the sensor is up to 0.9354 nm/(°) and the torsion angle range from -90° to +90°; When we increase the length of SLPCF to 32 cm, the torsion sensitivity of the sensor gets down to 0.2132 nm/(°), but the torsion angle range can be expanded as from -180° to +180°. To eliminate the perturbation of environmental temperature, we adopt a two-dimensional measuring matrix to achieve simultaneous measurements of the torsion angle and temperature. In other words, using two-dimensional measuring matrix can also eliminate the perturbation of the environmental temperature to the measured result of torsion angle.
Keywords： optical fiber sensor side-leakage photonic crystal fiber torsion sensor Sagnac interferometer