Ghenuche Petru, Rigneault Hervé, Wenger Jérôme
CNRS, Aix Marseille Université, Ecole Centrale Marseille, Institut Fresnel, 13013 Marseille, France.
Opt Express. 2012 Dec 17;20(27):28379-87. doi: 10.1364/OE.20.028379.
Current optical fiber probes for fluorescence spectroscopy struggle with large luminescence background and low detection sensitivities that challenge the detection of fluorescent molecules at sub-micromolar concentration. Here we report the demonstration of a hollow-core photonic crystal fiber (HC-PCF) probe for remote fluorescence sensing with single molecule sensitivity down to nanomolar concentrations, where both the excitation and fluorescence beams are counter-propagating through the same fiber. A 20 μm polystyrene microsphere is used to efficiently excite and collect the fluorescence from the sample solution thanks to a photonic nanojet effect. Compared to earlier work with silica fibers, the new HC-PCF-microsphere probe achieves a 200x improvement of the signal-to-noise ratio for a single molecule detection event, and a 1000x reduction of the minimum detectable concentration. The device is implemented with fluorescence correlation spectroscopy to distinguish between molecules of similar fluorescence spectra based on the analysis of their translational diffusion properties, and provides similar performance as conventional confocal microscopes.
当前用于荧光光谱分析的光纤探头存在较大的发光背景和较低的检测灵敏度问题，这对检测亚微摩尔浓度的荧光分子构成了挑战。在此，我们报告了一种中空芯光子晶体光纤（HC-PCF）探头的演示，该探头用于远程荧光传感，具有低至纳摩尔浓度的单分子灵敏度，其中激发光束和荧光光束都通过同一根光纤反向传播。由于光子纳米射流效应，一个20μm的聚苯乙烯微球被用于有效地激发和收集样品溶液中的荧光。与早期使用石英光纤的工作相比，新型HC-PCF-微球探头在单分子检测事件中实现了200倍的信噪比提升，以及最低可检测浓度降低1000倍。该装置通过荧光相关光谱法实现，基于对分子平移扩散特性的分析来区分具有相似荧光光谱的分子，并提供与传统共聚焦显微镜相似的性能。
