一种增强荧光远场定向发射的错位光栅结构

A Double-layer Dislocated Grating Structure for Enhancing Far-Field Fluorescence Emission

摘要:

针对荧光检测中荧光发射强度低且全方向发散等问题，本文提出了一种由双层错位金属光栅和倾斜电介质光栅组成的复合结构。采用时域有限差分法研究了量子点的偏振态、金属光栅参数对荧光定向发射增强的影响,并分析了荧光激发过程中的电场增强效果。通过将上转换量子点置于复合结构中的PMMA层，实现了荧光远场定向发射增强。研究表明，与自由空间中相比，当量子点处于错位金属光栅中时，荧光激发增强40倍，荧光定向发射增强26倍，且远场辐射角小，进而可以提高荧光生物检测的灵敏度。

Abstract:

In this paper, to solve the problems of low fluorescence intensity and omnidirectional divergence in fluorescence detection, a hybrid structure composed of a double-layer dislocation metal grating and an inclined dielectric grating was proposed. The effects of polarization state and position, metal grating period and parameters of quantum dots on the enhancement of fluorescence directed emission were studied by finite difference time-domain method, and the enhancement effect during fluorescence excitation was analyzed. By placing the up-conversion quantum dots as fluorescent materials in the polymethyl methacrylate layer, the structure achieves a significant effect of fluorescence far-field directional enhancement. The results show that compared with in free space, when the quantum dots are in the dislocated metal gratings, the fluorescence excitation is enhanced by 40 folds, the fluorescence directed emission is enhanced by 26 folds, and the far-field radiation angle is small, which can improve the sensitivity of fluorescence biological detection.