建立了一种基于闪耀光纤光栅(BFBG)透射特性的分布式光纤布拉格光栅(FBG)传感器的解调系统。由两个中心波长相近、光栅长度不同的FBG并联组成一个传感探头(FBG1用于参考, FBG2用于传感), 以消除温度对应变测量的影响。将BFBG 两端与加有10 Hz锯齿扫描电压的压电陶瓷(PZT)相固定, 使BFBG的主模和边模发生周期性的同向偏移, 对传感探头的光谱信号进行解调。从BFBG出来的透射光经光电管将光强变化转化为电信号, 用计算机对待测应变量进行实时分析显示。实验表明, 用BFBG进行光谱解调是可行的(微应变测量的分辨率为5 με), 并且成功地解决了温度和应变交叉敏感的问题, 所建立的实验系统稳定可靠, 成本低。

A new system on demodulation of distributed fiber Bragg grating (FBG) sensor is built using blazed fiber Bragg grating (BFBG). In order to eliminate the temperature effect on strain measurement, two adjacent FBGs (one for sensing, the other for reference) with similar central wavelength and different lengths as a probe by parallel connection are utilized. Both ends of the BFBG are connected to a piezoelectric (PZT)．A saw-tooth function voltage with 10 Hz signal is supplied to the PZT. The spectrum signal from the probe can be demodulated by the main mode and the side mode of BFBG periodically offset in the same direction. The transmitted light intensity is converted to electric current by a photodiode which is processed by a computer to display the detected strain in real time. Experimental results show that it is feasible to demodulate action spectrum by BFBG with the resolution of micro-strain detection of 5 με. The cross of FBG for temperature and strain is solved. It is testified that the system is stable, reliable, and less-expensive.