基于保偏光子晶体光纤的长尾式光纤环镜角度传感器

Torsion Sensor Based on Polarization-Maintaining Photonic Crystal Fiber Loop Mirror with an Output Port Probe

针对扭转角度的精确测量问题,提出一种基于保偏光子晶体光纤的长尾式光纤环镜角度传感器.采用对温度不敏感的保偏光子晶体光纤作为扭转角度的传感单元,当保偏光子晶体光纤被旋转一定角度时,其双折射值会发生改变,进而影响光在环镜系统内的干涉情况,最终表现为光谱仪上干涉谱的移动.理论推导出系统的传感规律后,实验测得该传感器在扭转角度为0°~101°的范围内,灵敏度为0.061 7 nm/（°）;若光谱仪分辨率为0.01 nm,则系统最小分辨力为0.16°,并具有超低的温度灵敏度-0.6 pm/℃.该角度传感器具有体积小、成本低、对温度不敏感及可用于远距离传输等优点.

Focused on measuring twist angle precisely,a torsion sensor was proposed which was based on a section of polarization-maintaining photonic crystal fiber（ PM-PCF） outside an optical fiber loop. Due to the lowthermal coefficient of PM-PCF,the PM-PCF was used as the sensing element. When the PM-PCF is rotated with a certain angle,the birefringence of the PM-PCF will change either. The interference within the fiber loop mirror was observed via the optical spectrum analyzer（ OSA）. The response of the sensor was deduced theoretically and experimentally demonstrated. Experimental result showed that the sensitivity of the developed torsion sensor could reach 0. 061 7 nm /（ °） in the range from 0° to 101° and a resolution of 0. 16° was achieved since the OSA had a wavelength measurement resolution of 0. 01 nm. In addition,the sensor has an ultra-lowtemperature sensitivity of- 0. 6 pm / ℃. The proposed fiber-optic torsion sensor is attractive due to its compact size,lowcost,insensitivity to temperature and suitability for long-distance transmission beyond what conventional sensors can offer.