光纤光栅法布里-珀罗传感器频分复用技术

理论分析了光纤光栅法布里-珀罗(F-P)传感器频分复用技术的原理,并给出了信号处理对腔长选取的要求。数值模拟结果表明,不同腔长的传感器具有不同的谐振条纹频率,为保证频域中的信号不发生重叠,要求不同光纤光栅法布里-珀罗传感器间的腔长之差必须大于光纤光栅的长度。进一步的实验及模拟分析结果发现,温度等待测量的变化仅仅使光纤光栅法布里-珀罗传感器的反射光谱整体平移,相应的频域信号只产生相移而形状不发生变化,因而不能采用普通光纤法布里-珀罗(FFP)传感器的腔长傅里叶变换解调法解调频分复用光纤光栅法布里-珀罗传感器的信号。根据这一特点,提出了利用自相关分析实现频分复用传感器系统信号解调的方案。

Frequency-Division Multiplexing Technique of Fiber Grating Fabry-Pérot Sensors

The principles of frequency-division multiplexing technique of fiber grating Fabry-Pérot (F-P) sensors were theoretically analysed and the restrictions on the length of F-P cavity for signal processing were given. The numerical simulation results shown that sensors with different cavity lengths are represented by different spectral fringe frequencies. To ensure that signals in the frequency domain will not overlap, the difference in the cavity length of any two fiber grating F-P sensors must exceed the length of fiber Bragg grating. The further experiment and simulation analysis also show that the change of measurands (i.e. temperature) will only cause the whole spectra shift without shape change, and the corresponding signal in the frequency domain produces only phase shift, so that the demodulation method based on Fourier transform for common fiber Fabry-Perot (FFP) sensor would be inapplicable here. According to this specialties of the frequency-division multiplexing signal, an autocorrelation analysis method has been suggested for the signal demodulation of this sensor system.