基于PCF-CNTs-AgNPs的全光纤表面增强拉曼散射气体检测关键技术研究

There is an urgent need to monitor air pollution with new air sensing systems. Firstly, a new gas sensor based on a hollow core photonic crystal fiber (HCPCF), carbon nanotubes (CNTs) and Ag nanoparticles (AgNPs) is proposed. The HCPCF can be used as a natural gas room, and also as a Raman spectrum collector with higher collection efficiency. The CNTs-AgNPs composite can be used as a surface-enhanced Raman scattering (SERS) substrate with a high enhancement factor, meanwhile the CNTs material can be used as a natural internal standard for gas concentration detection on different SERS substrates. Secondly, the physical model of the novel gas sensor is established. The structural design, the key process and the performance detection and optimization is carried on deeply. Furthermore, based on the characteristics of gas Raman spectra from the gas sensor, a tunable filter is adopted using a dual-mode photonic crystal fiber tunable acoustic optical band-stop filter and a fiber mode filter, with advantages of a wide wavelength range and high spectral resolution. Its design and manufacture is analyzed in details. Finally, an all-fiber Raman spectral readout and gas analysis system is designed and finished theoretically and experimentally. .. It is potential to make breakthroughs in enhanced Raman scattering signals and SERS quantitative detection. It is also potential to form a new miniature, low power, environment friendly, real time and online gas detection technology for applications of atmospheric monitoring nodes. And it can be promoted to the applications of the battlefield, fire rescue and other needs of portable trace gas detection.

为满足小型大气污染监测节点对新型气体检测系统迫切需求，本项目提出“空芯光子晶体光纤和碳纳米管-银纳米粒子复合结构作为气体传感器”的新思路，实现拉曼光收集效率提高、拉曼散射强度增强和不同增强基底的气体浓度自标定。建立此气体传感器的物理模型；研究其结构设计、关键工艺和性能测试优化。针对来自气体传感器的典型污染气体的拉曼光信号特征，采用“双模光子晶体光纤可调谐声光带阻滤波器和光纤模式滤波器级联”来实现光谱调谐范围宽、分辨率高的可调谐带通滤波，读取拉曼光谱信号。设计制作全光纤SERS气体检测系统，开展系统的实验研究。项目的研究成果，极有可能在气体拉曼散射信号增强和SERS检测的定量方面取得突破，形成适合大气监测节点的小/微型化、低功耗、环境适应性强、实时在线的气体检测新技术，满足国家大气污染监测体系中网格化监测节点的要求；并可推广战场、火灾救援等需要便携痕量气体检测的应用场合。

尽管激光拉曼散射光谱气体检测方法是大气污染监测的重要备选方案，但是它的研究现状还远没有达到现场小型监测节点对气体检测设备的要求；还有很多科学和技术问题亟待解决。针对现有激光拉曼散射光谱气体检测系统的不足，本项目开展“基于PCF-CNTs-AgNPs 的全光纤表面增强拉曼散射气体检测关键技术研究”。主要包括三方面的工作：①结构化光纤SERS机理和实验研究，②波导/光纤-SERS传感理论模型和实验研究，③拉曼光谱解调系统机理和实验研究。（1）围绕结构化光纤SERS机理和实验，我们主要开展了：自组装单层银纳米颗粒SERS基底的机理及性能，三维金属纳米颗粒-石墨烯-金属纳米颗粒结构化SERS，微球辅助银纳米粒子结构化SERS基底，银纳米岛/氧化铝/银纳米粒子的SERS基底及其拉曼增强特性，类火山-银纳米粒子复合结构拉曼增强特性，自清洁的结构化SERS基底及其性能，低成本柔性结构化SERS基底及其性能。SERS基底的增强性能（增强因子10^12）、均匀性（标准相对偏差RSD小于10%）、稳定性等得到极大提高。（2）围绕波导/光纤-SERS传感理论模型和实验开展了：波导-SERS传感理论研究，自标定SERS传感机理和实验研究，FP-SERS双增强光纤拉曼传感器耦合机理及性能，锥形光纤SERS探针优化及其性能。揭示了光纤/波导-SERS传感机理和自标定机制，实现了分子的自标定检测。（3）围绕拉曼光谱解调系统机理和实验，主要开展了：背向和垂向拉曼增强的自组装AgNPs修饰的高灵敏度D型光纤探针，动态马赫贞德干涉仪-傅里叶变换全波导拉曼光谱检测系统，基于cvx凸优化算法的微环谐振器阵列光谱检测系统。在光纤/波导拉曼光谱解调方面有了突破，光谱解调系统可以在片上实现，系统工作带宽为12 nm, 分辨率优于0.17 nm。.项目的研究成果可以推广到现场手持检测、无人机机载监测和流动检测车载检测；工业、战场、火灾救援等需要对多种类痕量分子进行快速定性、定量测量的场合，极大地拓展激光拉曼散射技术的范围。