基于光生相敏的光纤双波长共光路高灵敏气体传感方法研究

Fiber optical technology can detect physical parameters more sensitive by detecting the phase change of the laser. In this project, the energy change of the laser caused by gas absorption is converted into the phase change of the laser, and then the phase interference demodulation is used to realize the highly sensitive gas sensing. Firstly, the physical process of phase changing generation with gas absorption (light generate phase sensitive) is researched. Secondly, the symbiotic relationship between the absorption and the phase of the laser is established, so that the gas absorption intensity can be converted into laser phase change. Third, the design of dual-wavelength common optical path sensor structure scheme is designed. Separation of the phase detection and spectral absorption is used to eliminate cross-interference from spectral absorption and phase change. Fourth, phase detection signal is locked with modulation signal of excitation light by a lock-in mathod to further improve the signal-to-noise ratio. Through the above, a new type of optical fiber gas sensor based dual-wavelength common optical path is researched, and it can achieve a new method of high sensitive gas sensing.

光纤技术中通过检测激光的相位变化可以实现更高灵敏的物理参量检测。本课题通过将气体对激光的能量吸收转换为激光的相位变化，再利用相位干涉解调实现高灵敏气体传感方法的研究。首先，针对光谱吸收产生相位敏感（光生相敏）的物理过程开展研究，探索激光传播通道内的光晕效应；其次，建立激光光谱吸收与传播相位变化的共生关系，将气体吸收强度转化为激光相位变化量；第三，设计双波长共光路的光纤传感结构方案，将相位探测与光谱吸收从波长上分开，消除光谱吸收与相位变化的交叉干扰；第四，研究通过同频锁相的方法，将用于气体吸收的激励光源进行强度调制，并与相位检出信号同频锁相，进一步提高检出信号的信噪比，最终实现一种新型基于光生相敏的光纤双波长共光路高灵敏气体传感新方法。

气体检测技术在人类生活的各个方面都发挥着极为重要的作用，特别是环境监测、工矿生产安全、管道泄漏、化工生产及安全等领域，是必不可少的技术。为了消除传统电子传感器带来的安全隐患，激光光谱吸收式光学气体传感器已成为现代科技研发的热点。本项目采用光纤技术，利用气体吸收激光并造成激光参数的改变作为传感技术原理，实现了高灵敏气体检测。首先，课题重点研究了传感原理，构建了传感理论模型，搭建了测试实验并形成样机系统。其次，为进一步提高该方法的实用性，还对外界温度、压力等因素会对检测技术造成的影响进行了深入研究，消除了谱线加宽的影响，实现了补偿修正。最后，针对不同气体间的交叉干扰问题，开展了多组分气体间交叉干扰修正算法-独立成分分析算法的研究工作，提高了传感探测精确度和稳定性。