基于光纤液体微腔的回音壁模式及微流传感研究

To overcome the scientific problems that whispering gallery mode(WGM ) cavity and the coupler are spatially separated, and the boundary of the liquid cavity is unstable, an in-fiber WGM liquid microcavity is proposed and its microfluidic sensing is studied in this project. It is proposed to use an all-fiber structure integrated a liquid core waveguide and a liquid microcavity, and the device can be applied to many research fields such as biodetection, microfluidic laser sensing, microcavity lasers and cell lasers through establishing a microfluidic channel. The problem that liquid microcavity boundary is instability will be solved using a novel method, i.e. an standard spherical "air-bubble microcavity" creating in fiber cladding is used as a "coat" providing a stable boundary condition for the liquid microcavity, thus the liquid microcavity has more stable mechanical properties. That is the liquid microcavity is formed by filled the bubble microcavity with high refractive index liquid. The fiber liquid core waveguide is fabricated by filling the high refractive index liquid into an in-fiber High-Q microfluidic channels, which is created by femtosecond laser wet etching technology. The excitation and collection of the liquid-cavity’s WGM is realized using the liquid core waveguide under a critical coupling gap between the liquid core coupler and the liquid microcavity. Constructing fiber microfluidic channel, the In-fiber whispering-gallery-mode liquid mricrocavity can be used for optofluidic sensing.

针对光学回音壁微腔与耦合波导的分离结构以及液体微腔边界不稳定的科学难题，本项目提出基于光纤液体微腔的回音壁模式及微流传感研究。拟采用液芯波导与液体微腔的全光纤集成结构，利用液芯波导耦合激发和收集液体微腔的回音壁模式，通过构建光纤内部微流通道使得该器件可应用在生物检测、微流传感、微腔激光以及细胞激光器等众多研究领域。项目采用一种全新思路解决液体微腔边界不稳定难题：利用光纤包层内的标准圆球形“气泡微腔”为液体微腔穿上一个稳定的“外衣”，为液体微腔提供了稳定的边界条件，使液体微腔具备更加稳定的机械性能，即气泡微腔内填充高折射率液体形成液体微腔；通过飞秒激光湿法刻蚀技术在光纤内制备高质量的微流通道，填充高折射率液体实现液芯波导功能；控制临界耦合距离，利用液芯波导耦合激发和收集液体微腔的回音壁模式；通过构建微流通道实现基于光纤液体微腔回音壁模式的微流传感。

该项目支持下，成功搭建了基于氢氧焰、CO2激光和飞秒激光的高质量光纤微腔加工系统，明晰了微纳光纤波导及光纤微腔耦合机理；研制出基于光纤气泡微腔和螺旋微结构光纤的一系列传感器样品，将其成功应用于生物微流传感技术，实验获得特异性IgG 检测，实现0.018nm/(g/mL) 的高灵敏度和4.7 g/mL 的检测限(LOD)；此外，优化了传感器结构实现了超高灵敏度的折射率传感器，且传感灵敏度高达为~25546 nm/RIU，并且有效降低了温度、应变引起的波长漂移交叉干扰，该类传感器及系统为光纤生物微流传感技术发展奠定了良好基础。在该项目支持下，申请专利9项且获得9项专利授权；发表SCI期刊论文10篇（中科院JCR二区以上论文8篇）；培养博士生1名、硕士研究生4名、博士后1名。