该文提出了一种基于飞秒激光直写的高灵敏度光纤光栅折射率传感器, 同时测量了传感器的温度及轴向应变特性。采用波长为800 nm的飞秒激光刻写了周期为150 μm, 周期数为50, 栅区长度为7.5 mm的长周期光栅。该传感器在折射率测量实验中的灵敏度最高可达1 605 nm/RIU, 在30~330 ℃, 温度灵敏度达到76.52 nm/℃, 传感器的稳定性良好且对应变不敏感, 鲁棒性优良。这种基于飞秒激光直写的长周期光纤光栅, 其折射率灵敏度较高, 耐高温, 具有广泛的应用前景。

In this paper, a high-sensitivity fiber grating refractive index sensor based on direct femtosecond laser writing is proposed, and the temperature and axial strain characteristics of the sensor are also measured. A long-period grating with a period of 150 μm, a period number of 50, and a gate length of 7.5 mm was inscribed with a femtosecond laser at a wavelength of 800 nm. The sensitivity of the sensor in refractive index measurement experiment is up to 1 605 nm/RIU and a temperature sensitivity of 76.52 nm/℃ in the temperature range of 30 ℃ to 330 ℃. The sensor is stable and insensitive to strain with excellent robustness. This long-period fiber grating based on femtosecond laser direct writing with high refractive index sensitivity and high temperature resistance has a wide application prospect.