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 Enhanced Far-Field Fluorescence Emission

针对荧光检测中荧光发射强度低且全方向发散的问题,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和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聚甲基丙烯酸甲酯层,实现了荧光远场定向发射增强。研究结果表明,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。

This study proposes a hybrid structure consisting of a double-layer dislocated metal grating and an inclined dielectric grating to address the issues of low fluorescence intensity and omnidirectional divergence in fluorescence detection.Using the finite-difference time-domain method,we investigated the effects of polarization state and position,quantum dot positioning,and metal grating period on enhancing directed fluorescence emission.Additionally,we analyzed the enhancement effect during fluorescence excitation.By embedding the up-conversion quantum dots as fluorescent materials within the polymethyl methacrylate layer,the proposed structure achieved significant fluorescence far-field directional enhancement.The results demonstrated that,compared to free space,when quantum dots were placed in dislocated metal gratings,fluorescence excitation was enhanced by 40-fold,directional fluorescence emission was increased by 26-fold,and the far-field radiation angle was reduced,thereby improving the sensitivity of fluorescence-based biological detection.