基于碳纳米材料的倾斜光纤光栅倏逝场调控及其传感应用

Tilted fiber Bragg grating (TFBG) exhibits unique advantages in multi-parameters sensing due to its special grating structure and various spectral characteristics, which provides a new effective approach for remote monitoring of environmental parameters, and becomes one of the new hotspots in optical fiber sensing technique. This project aims to combine the TFBG, D-shaped/tapered fiber and carbon nanomaterials (graphene and carbon-nanotubes), then explore the generation mechanism of new resonances and the enhancement effect of the evanescent field，and develop several sensing methods with broad response range and high sensitivity in environmental parameters measurements. The main contents of this project are included: ① the interaction mechanism between the fiber evanescent field and the carbon nanomaterial coating; ② the TFBG spectral modification caused by the carbon nanomaterials and its coupling sensing mechanism; ③ the design and optimization of the sensing system based on carbon nanomaterial-coated TFBG. The key scientific problems to be solved are: the modulation of the mode coupling behavior and evanescent field distribution of special TFBG, the parameter control and characterization of the carbon nanomaterial coating of fiber surface. The results obtained from above studies can not only help to reveal new coupling sensing mechanism of fiber-optic evanescent field, but also solve the key scientific problems of the TFBG in temperature, relative humidity, refractive index, the composition and content of contaminants and other environmental parameters monitoring. The proposed method and system is expected to be applied extensively in the fields of environmental monitoring and pollution treatment.

倾斜光纤光栅（TFBG）因其特殊的光栅结构和丰富的光谱特征，在多参量传感测量中具有独特的优势，为环境参数远程监测提供了新的有效途径，成为光纤传感技术中新的研究热点之一。本项目旨在结合TFBG、D型/锥形光纤与碳纳米功能材料（石墨烯和碳纳米管），探索其特殊谐振模式的产生机理和倏逝场的增强效应，发展具有宽响应范围、高灵敏度的环境参量传感方法。具体包括：①光纤倏逝场与碳纳米材料涂覆层的相互作用机理；②碳纳米材料对TFBG光谱的修饰规律及其耦合传感机制；③碳纳米材料涂覆特殊TFBG的传感系统设计与结构优化。拟解决的关键科学问题：碳纳米材料对特殊TFBG模式耦合行为和倏逝场分布的调控规律，光纤表面碳纳米材料涂覆参数控制及特性表征。研究成果不仅有助于揭示新型光纤倏逝场的耦合传感机制，还可以解决TFBG在温湿度、折射率及污染物成分和含量等参量传感中的关键问题，使其在环境监测以及污染治理中得到广泛应用。

采用具有丰富光谱特征和独特倏逝场分布的倾斜光纤光栅，为以折射率传感为基础的多种参数测量提供了一种新的有效途径，并展现了诸多独特的优势。本项目完成的研究内容包括：① 研制了小角度倾斜光纤布拉格光栅（TFBG）、大角度倾斜光纤光栅（Ex-TFG）、微光纤光栅、D型光纤光栅等多种光纤光栅结构，并分析了其模场分布和光谱特征；② 研究了碳纳米材料对多种光纤光栅光谱的修饰规律、偏振调制特性及其耦合传感机制，功能化倾斜光纤光栅表面在生物传感中的应用；③ 通过结合D型光纤光栅和干涉仪结构，研究了其光谱特征、以及在传感和光调制方面的应用等。取得的研究成果主要有：① 建立了碳纳米材料与倾斜光纤光栅（包括TFBG和Ex-TFG）的复合波导模型，分析了涂覆介质对光谱和模场的修饰规律；② 利用碳纳米材料修饰多种倾斜光纤光栅实现了折射率、弯曲、葡萄糖等物理与生化参量的传感；③ 利用石墨烯对包层模的调制，揭示了Ex-TFG包层模的独特偏振调制特性。因而，通过结合多种倾斜光纤光栅与碳纳米材料，揭示了新型光纤倏逝场和包层模式的调制机理，发展了多种具有宽响应范围、高灵敏度的多参量传感方法，在环境监测、生化传感等领域具有广泛的应用价值。