掺Er3+光纤激光内腔光声光谱气体传感的研究

项目名称： 掺Er3+光纤激光内腔光声光谱气体传感的研究

项目编号： No.61475085

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 无线电电子学、电信技术

项目作者： 常军

作者单位： 山东大学

项目金额： 82万元

中文摘要： 本研究利用激光谐振腔内具有高光功率密度及光往返传播特点，提出掺Er3+光纤激光内腔光声光谱气体传感方法，将气体传感用的光声池与光纤激光器谐振腔融合，以提升光纤气体传感器的灵敏度。理论上建立描述光纤激光谐振腔中光声池内光声信号产生的模型，研究调制频率及强度调制下占空比与波长调制下调制幅度等参数对光声信号产生的影响，对比波长调制与光强调制两种方式的效果，确定光纤激光器的最佳工作方式及参数，实验上设计、制作反射式倏逝场型光声池与准直器型光声池，并对比它们的效果，采用聚声腔和石英音叉两种方式对光声信号强度进一步提升；在理论模型结论的基础上进一步优化激光器的参数以增强光声信号，构建内腔光声气体传感系统，以乙炔气体验证标定传感性能，评价内腔光声传感相比普通光声传感灵敏度的提升效果，实现ppb量级的传感灵敏度，本研究在学术上将促进光学有源传感领域的发展，而且，光纤气体传感器灵敏度的提升有很好的应用价值。

中文关键词： 光纤传感；气体检测；光声光谱；激光谐振腔；掺铒光纤

英文摘要： Lasers have the characteristics of high power density and round-trip propagation inside resonant cavity. Taking advantage of that, an Er3+ doped fiber laser based photoacoustic gas sensing method is proposed by this research. Sensitivity of fiber gas sensor is improved by merging the photoacoustic cell for gas sensing and resonant cavity of fiber laser. Theoretically a model is built to describe the generation of photoacoustic signal inside fiber laser resonant cavity. Parameters, for example, the duty cycle under frequency modulation or intensity modulation and the modulation amplitude under wavelength modulation are studied to figure out their influence on photoacoustic signal. Effect of wavelength modulation and intensity modulation is compared to confirm the optimal working pattern and parameters. Experimentally reflecting evanescent-field photoacoustic cell and collimator based photoacoustic cell are achieved to compare the effect. Converging acoustics cavity（Acoustic resonator） and quartz tuning fork are used to achieve to the promotion of photoacoustic signal. Based on the conclusions of theoretical model, parameters of fiber laser are further optimized to enhance the photoacoustic signal. Then an intra-cavity photoacoustic gas sensing system is built. Acetylene is used to verify its performance and evaluate the promotion effect of intra-cavity photoacoustic sensing in the aspect of sensitivity compared to ordinary photoacoustic sensing. The magnitude of sensitivity is achieved to be ppb. This research will facilitate academic development in the field of optical active sensing, and the promotion of optical gas sensing sensitivity is of good application value.

英文关键词： fiber optic sensor;gas sensor;photoacoustics spectrum;laser resonator;erbium doped fiber