State Key Laboratory of Surface Physics and Department of Physics, Human Phenome Institute, Academy for Engineering and Technology, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai 200433, China.
Yiwu Research Institute, Fudan University, Chengbei Road, Yiwu 322000, China.
Biosensors (Basel). 2022 Apr 14;12(4):243. doi: 10.3390/bios12040243.
Stimulated Raman scattering (SRS) is known to gain coherent amplification of molecular vibrations that allow for rapid and label-free chemical imaging in the microscopy setting. However, the tightly focused laser spot has limited the detection sensitivity, partly due to the tiny interaction volume. Here, we report the use of metal-lined hollow-core fiber (MLHCF) to improve the sensitivity of SRS in sensing dilute solutions by extending the light-matter interaction volume through the fiber waveguide. With a focusing lens (100 mm FL) and 320 μm diameter fiber, we demonstrated an optimum enhancement factor of ~20 at a fiber length of 8.3 cm. More importantly, the MLHCF exhibited a significantly suppressed cross-phase modulation (XPM) background, enabling the detection of ~0.7 mM DMSO in water. Furthermore, the relationship between fiber length and SRS signal could be well explained theoretically. The fiber-enhanced SRS (FE-SRS) method may be further optimized and bears potential in the sensitive detection of molecules in the solution and gas phases.
受激拉曼散射（SRS）能够对分子振动进行相干放大，从而实现显微镜环境下的快速、无标记化学成像。然而，由于激光光斑的高度聚焦，其检测灵敏度受到限制，这部分归因于微小的相互作用体积。在这里，我们报告了使用金属衬里空芯光纤（MLHCF）通过光纤波导来扩展光物质相互作用体积，从而提高 SRS 在感测稀溶液中的灵敏度。使用聚焦透镜（100mm FL）和 320μm 直径光纤，我们在光纤长度为 8.3cm 时实现了约 20 的最佳增强因子。更重要的是，MLHCF 表现出显著抑制的交叉相位调制（XPM）背景，能够检测到水中约 0.7mM 的 DMSO。此外，纤维长度与 SRS 信号之间的关系可以从理论上得到很好的解释。纤维增强受激拉曼散射（FE-SRS）方法可以进一步优化，并在溶液相和气相中对分子的灵敏检测中具有潜在应用。
