超低温环境下光纤布里渊频移特性研究

针对高温差和超低温广泛存在的空间环境，了解航天器材料及结构的热应变稳定性对于保障航天环境模拟地面试验的可靠性具有重要意义。布里渊光时域分析（BOTDA）技术能够同时检测温度和应变，且具有高精度、长传感距离、抗电磁干扰及低成本等优势，但作为传感元件的光纤能否适应空间冷黑环境还未可知。文章首先利用BOTDA解调仪获取了2种典型标准单模光纤在超低温下的布里渊增益谱（BGS），然后通过实验数据分析光纤的超低温性能，最终标定了2种光纤的温度和应变系数。结果表明，受试光纤在超低温下仍能形成洛伦兹形状的BGS，且实际频移量与低温对应的理论频移量一致，满足超低温空间环境下BOTDA传感器的测温范围要求。

Investigation on Brillouin frequency shift characteristics of optical fiber under ultra-low temperature

Aiming at the space environment with widespread high temperature difference and ultra-low temperature, it is important to understand the thermal strain stability of spacecraft materials and structures for ensuring the reliability of simulated ground-based space environmental tests. Brillouin optical time domain analysis (BOTDA) technology can simultaneously detect temperature and strain, and has the advantages of high precision, long sensing distance, anti-electromagnetic interference and low cost. However, it is unknown whether the optical fiber as a sensing element can adapt to the cold and black space environment. In this paper, the Brillouin gain spectra (BGS) of two typical standard single-mode optical fibers at ultra-low temperature were firstly obtained by BOTDA demodulator. Then, the ultra-low temperature performance of the optical fibers was analyzed through experimental data. Finally, the temperature and strain coefficient of the two optical fibers were calibrated. The results show that the tested optical fibers can still form a Lorentz shaped BGS at ultra-low temperature, and the actual frequency shift is consistent with the theoretical frequency shift corresponding to the low temperature, which meets the temperature measurement range requirements of BOTDA sensor in the ultra-low temperature space environment.