F-P标准具和参考光栅相结合的高稳定性FBG解调系统

High stability FBG demodulation system combining F-P etalon with reference grating

为了提高光纤布喇格光栅(FBG)解调系统的稳定性和准确性,避免由于压电陶瓷的迟滞性、蠕变性以及温度变化引起的法布里-珀罗(F-P)滤波器驱动电压与透射波长不成线性的问题,采用了可调谐环形腔激光器作为扫描光源,与F-P标准具、温补参考光栅、传感光栅3个单独的通道结构相结合的FBG解调方法。通过理论分析和实验验证,选择中值滤波加滑动平均滤波的方法滤除噪声,采用基于强度阈值的频谱相关寻峰算法更加准确地找到反射谱峰值的位置。结果表明,每个通道单独分开的解调方案的波长长期稳定性可达0.4pm,温度与波长的线性度高于99.90%。该系统能够实现对温度、应变等参量的稳定性的测量。

In order to improve the stability and accuracy of a fiber Bragg grating(FBG)demodulation system and avoid the problem of nonlinearity of driving voltage and transmission wavelength of a Fabry-Perot(F-P)filter caused by hysteresis,vermicular and temperature changes of the piezoelectric ceramic,a FBG demodulation method was introduced combining with F-P etalon,temperature-compensated reference grating and sensing grating in three separate channels with a tunable ring cavity laser as scanning light source.The method of median filtering and moving average filtering was selected to filter the noise.A spectral correlation peak-seeking algorithm based on intensity threshold was used to find the location of peak value of reflection spectrum more accurately.Through theoretical analysis and experimental verification,the results show that wavelength long-term stability of demodulation scheme with each separated channel can reach 0.4pm and the linearity between temperature and wavelength is higher than 99.90%.The system can measure the stability of the parameters such as temperature and strain.