荧光分子自发辐射的发散性以及低辐射效率制约了单分子荧光传感光信号的捕获, 电介质纳米圆柱能够有效提高荧光分子的定向发光强度。利用时域有限差分(FDTD)法, 理论研究了荧光分子的振荡方向、荧光分子与纳米圆柱的距离、纳米圆柱的折射率和直径对定向发光增强的影响。结果表明: 当纳米圆柱的折射率为1.7、荧光分子的振荡方向沿圆柱的轴向、纳米圆柱具有更大的直径且荧光分子离纳米圆柱的距离更小时, 荧光的定向增强效果更好。当纳米圆柱直径为1 μm、荧光分子距离纳米圆柱10 nm时, 荧光定向增强约为10倍, 定向发射角约为16.1°。

The divergence of spontaneous radiation of fluorescent molecules and low radiation efficiency limit the capture of optical signals in single-molecule fluorescence sensing, and dielectric nanocylinders can effectively improve the directional luminescence intensity of fluorescent molecules. By the finite difference time domain (FDTD) method, it is theoretically studied that the oscillation direction of fluorescent molecules, the distance between the fluorescent molecules and nanocylinders, the refractive index of nanocylinders and the diameter of nanocylinders influence the directional luminescence enhancement. The results show that when the refractive index of the nanocylinder is 1.7, the oscillation direction of the fluorescent molecule is along axial direction of the cylinder, the nanocylinder has a larger diameter and the distance of the fluorescent molecule from the nanocylinder is smaller, the fluorescence directional enhancement effect is better. When the diameter of the nanocylinder is 1 μm and the fluorescent molecule is 10 nm from the nanocylinder, the fluorescence directional enhancement is about 10 times and the directional emission angle is about 16.1°.