旋转折变型长周期光纤光栅实现应变和温度的同时测量

Simultaneous Measurement of Strain and Temperature Using a Long-Period Fiber Grating with Rotary Refractive Index Modulation

提出一种基于旋转折变型长周期光纤光栅(R-LPFG)实现应变和温度同时测量的新方法。旋转折变型长周期光纤光栅是利用高频CO2激光在扭曲的普通单模通信光纤上制作的。这种特殊折变结构实现了纤芯基模与非对称包层模L1k奇模和偶模的同时耦合,从而导致R-LPFG的谐振峰发生分裂。通过对这种光栅的应变和温度特性进行实验研究发现,当对它施加轴向应力时,其传输谱的两个谐振峰会向不同方向漂移;而当外界温度改变时,两个峰则会向同一方向漂移且波长漂移灵敏度几乎相同,大约为0.07 nm/℃。

A new method to realize simultaneous measurement of strain and temperature by using a long-period fiber grating with rotary refractive index modulation （R-LPFG） which fabricated in twisted common communication optical fiber by using high-frequency CO2 laser pulses, is reported. The fundamental core mode of R-LPFG simultaneously couples to the odd and the even modes of the asymmetric cladding modes （L1k） due to especial refractive index distribution, which leads to two separated resonant peaks of R-LPFG. The strain and temperature characteristics of R-LPFG are studied experimentally. The results show that the two split resonant peaks continue separating when the strain was applied to it, but shift to the same direction and almost have the same temperature sensitivity when the environmental temperature changes. The temperature sensitivities are about -0.07 nm/℃.