基于硅基光子晶体微流通道的荧光定向发射增强特性研究

Directional Fluorescence Emission Enhancement Using Silicon-based Photonic Crystal Microfluidic Channels

为提高荧光检测的灵敏度,提出一种基于硅基光子晶体的微流通道结构。该结构可以有效增强通道内激发光场,实现量子点的荧光定向发射。利用平面波展开法计算光子晶体的能带结构,同时借助时域有限差分法详细研究了量子点偏振、通道结构参数,以及通道内量子点位置对荧光发射的影响。此外,还分析了该结构在量子点激发过程中的增强效应。仿真结果表明,与传统硅微流通道相比,光子晶体微流通道具有更高的远场发射功率以及更窄的辐射角;与玻璃基底相比,光子晶体微流通道中的量子点远场功率达到了16.9倍的增强以及9°以内的窄角发射;光子晶体微流通道对945 nm的激发光场实现了平均7.9倍的增强。

To improve the sensitivity of fluorescence detection,a microfluidic channel structure using silicon-based photonic crystals is proposed.The microfluidic channel can effectively enhance the excitation light field and realize fluorescence-directed emission of quantum dots.The band structure of the photonic crystal was determined by the plane wave expansion method.The effects of quantum dot polarization,channel structure parameters,and the position of quantum dots in the channel on fluorescence emission were examined using the finite-difference time-domain method.In addition,the enhancement effect of the structure during the excitation of quantum dots was analyzed.The simulation results show that,compared with the traditional silicon microfluidic channel,the photonic crystal microfluidic channel has a higher far-field emission power and a narrower radiation angle.Compared with the glass substrate,the far-field power of quantum dots in the microfluidic channel of the photonic crystal achieves a 16.9-fold enhancement and a narrow-angle emission within 9°.The photonic crystal microfluidic channel achieves an average 7.9-fold enhancement of the excitation field at 945 nm.