基于微流控光学可调谐的渐变折射率特性研究*

摘要

本文基于层流液体的对流扩散效应，提出了一种新型的具有渐变折射率分布特性并且可以实现调节的微腔流体透镜。利用有限元法分析微腔中芯层与包层流体在对流扩散过程达到稳定后的浓度分度，即混合流体的折射率分布，结果表明，分别调节芯层与包层流体的流速，微腔中的流体可以实现不同的渐变折射率分布。同时，本文还分析了即使考虑腔壁与流体之间的黏滞阻力因素，芯层与包层流体的流速组合依然是混合流体折射率分布的决定因素。应用微腔流体透镜的这种调节效果，可以实现不同要求的光束聚焦、分束、偏转等功能，在微流控光学检测系统以及微成像系统中有重要的应用。%A new type of tunable gradient-index (GRIN) microfluidic lens is proposed, which is based on the convection-diffusion process. By using the finite element method, the spatial distribution of the refractive-index (RI) determined by the concentration distribution in the microchannel is analyzed. Results show that the distribution of RI in the microchannel can be tuned by different flow rates of the core and cladding liquid streams. Furthermore, although taking into consideration the existence of the viscous resistance between the channel wall and the flowing stream, the RI distribution is still dependent on the combination of flow rates of the core and cladding streams. This microfluidic lens can be applied to dynamic adjustment of focusing, splitting or bending light beams. It therefore may have extensive applications in the optofluidic optical detecting system and microscale imaging system.