利用光纤偏振分束器和保偏光纤的传感解调系统

提出了一种利用光纤偏振分束器(PBS)和保偏光纤(PMF)中偏振模间干涉原理实现光纤布拉格光栅波长解调的方案,以提高光纤光栅传感解调系统的解调精度和稳定性。运用矩阵光学原理建立了数学分析模型,由此给出了系统输出信号与光纤光栅布拉格波长之间的关系。通过仿真分析,研究了保偏光纤长度、输入光相对于保偏光纤主轴的偏振角度和光纤偏振分束器主轴方位对系统输出信号的影响,明确提出了提高系统灵敏度的方法。根据设计方案搭建了实验系统,并进行了实验验证。结果表明:该设计方案可行,系统的波长分辨率1pm,测量精度1pm,温度可测量范围为90℃。该系统测量精度高,其稳定性优于利用M-Z型干涉仪的解调装置。

Sensor demodulation system using PBS and PMF

A demodulation scheme based on Polarizing Beam Splitters (PBS) and inter-modal polarization interference in Polarization-maintaining Fibers(PMFs)was proposed to implement the wavelength demodulation of fiber Bragg grating sensors and to improve their precisions and stabilities. Using the principle of matrix optics, the mathematic model was established theoretically and the relations of system output signals and Bragg wavelengths of fiber gratings were obtained. The influences of the length of the polarization-maintaining fiber,polarized angles of input light to the principal axis of PMF and the orientation of PBS principal axis on output signals were researched and a method to improve the sensitivity of the system was presented. On the scheme above,an experimental system was set up. The results demonstrate that the scheme is feasible, in which the average precision of the wavelength demodulation is lower than 1 pm and the temperature measurement range is 90 ℃. The demodulation system has higher precision and its stability is better than that of the M-Z interference device.