基于氧化石墨烯增强倾斜光纤光栅泄漏模谐振的生物传感研究

Tilted fiber Bragg grating (TFBG) shows sensitive comb-like spectrum, which has been widely used for modern biosensors. The sensing schemes of the TFBG sensors in previous reports are mainly based on the resonances corresponding to cladding mode, cut-off mode, and surface Plasmon resonance. However, the leaky mode resonance has been generally ignored due to its extremely weak resonance strength. In fact, the leaky mode resonance can be greatly enhanced by integrating the graphene layer on the TFBG and shows ultra-sensitive sensing characteristics. In this project, we propose and study a novel graphene oxide (GO) enhanced leaky mode resonance of the TFBG for biosensing. The main research contents are as follows. (1) We firstly establish an efficient and accurate adaptive finite-difference based coupling mode theory for the GO integrated TFBG; (2) Then the influence of the GO on the generation and evolution of the leaky mode is explored, the internal relationship between the reflections of different order leaky modes and its polarized spectra is established, and the enhancement mechanism and optimization method of the leak mode resonance are obtained; (3) Finally the GO enhanced leak mode resonance sensing system is fabricated based on the microfluidic chip technology for the specific detection of immunoglobulin G (IgG). The GO enhanced leaky mode resonance of the TFBG that is investigated in this project will greatly improve the sensitivity, effectively reduce the limit of detection (LOD), and promise to be a novel sensing platform with the characteristics of high sensitivity, low LOD, label-free and on-line in-situ detection for fiber optic trace biosensing.

倾斜光纤光栅（TFBG）因具有灵敏的梳状光谱而被广泛应用于现代生物传感。现有方案主要基于包层模、截止模及表面等离子体共振等，泄漏模谐振因非常微弱而常被忽略。但事实上，泄漏模谐振可通过石墨烯极大增强且具有诱人的高灵敏传感特性。鉴此，本项目提出新型氧化石墨烯（GO）增强TFBG泄漏模谐振并用于生物传感。主要研究内容包括：（1）构建高效精确的GO集成TFBG自适应有限差分及模式耦合分析模型；（2）探究GO对泄漏模产生及演化的影响规律，建立不同阶泄漏模反射与偏振光谱间的内在联系，得到泄漏模谐振增强机理及传感优化方法；（3）结合微流控芯片技术研制GO增强TFBG泄漏模谐振生物传感系统，开展免疫球蛋白G（IgG）特异性检测研究。本项目研究的GO增强TFBG泄漏模谐振将有效提高生物传感灵敏度并进一步降低检出限，有望发展为一种新的具有高灵敏、低检出限、免标记、在线原位检测等优异特性的光纤痕量生物传感技术。

泄漏模是不满足波导传播条件的高阶模式，因其高损耗特性而长期被忽视。本项目从石墨烯集成光纤泄漏模谐振出发，研究纳米薄膜材料对光纤器件的光波传输、模式耦合、偏振特性以及光谱分布等特性的作用机制与调控规律。本项目完成的主要研究内容包括：①石墨烯激发倾斜光纤光栅（TFBG）泄漏模谐振的产生机理与传感特性；②纳米材料集成光纤泄漏模谐振及其多元参量传感特性；③TFBG表面波导模谐振传感器件。取得的主要研究成果包括：①基于改进的自适应有限差分算法建立了石墨烯集成TFBG器件的全矢量理论分析模型，大幅减小了光纤器件的仿真计算时间；②揭示了石墨烯集成TFBG泄漏模谐振的产生机理、演化规律、模场与光谱调控特性，得到了泄漏模界面反射与偏振光谱的内在联系；③利用石墨烯独特的偏振调控特性，实现了石墨烯增强TFBG泄漏模谐振的高灵敏折射率传感，得到了其传感优化方法；④发展了多种类型纳米材料集成TFBG泄漏模谐振传感与滤波器件，揭示了纳米材料与光纤泄漏模的相互作用机制；⑤提出并实现了光纤探针泄漏模谐振体/面多元参量传感，得到了光纤探针泄漏模的模式方程、激发原理与多元传感特性；⑥提出并研究了金包层介质薄膜波导集成TFBG表面波导模谐振传感器件，阐明了薄膜诱导光纤模式转换的本质原因、偏振调控规律以及高灵敏传感特性。因此，本项目的研究工作不仅揭示了系列纳米薄膜材料对光纤模式和光谱的作用机制与调控规律，而且扩展了纳米薄膜集成光纤器件的在高灵敏多元参量传感、光纤偏振调制器件等领域的应用。相关研究成果共发表学术论文16篇，其中SCI收录论文14篇，EI收录论文1篇（《光学学报》特邀论文），EI收录国际会议论文1篇；申请国家发明专利7项（已获授权4项），申请美国发明专利1项。此外，参加国内/国外学术会议报告4次，学术交流汇报1次等。