Wang Fangzhou, Kang Guoguo
Appl Opt. 2018 Jan 10;57(2):237-241. doi: 10.1364/AO.57.000237.
An improved bull's eye nanostructure is proposed as a substrate for surface-enhanced fluorescence. Optimized by finite-difference time-domain, annular corrugation on both upper and lower surfaces is placed around a nanobow tie in the middle. The whole structure is designed for the excitation and emission process of a certain fluorescence simultaneously, which can enhance the fluorescence intensity enormously (35 times for an excitation field and 120 times for radiation, independently). Meanwhile, it is able to confine the far-field emission energy within a divergence angle of ±3.5°. The dual-resonant enhancement and directivity of such a substrate allows higher sensitivity during fluorescence detection. Furthermore, the designed resonance and directional light control at emission may effectively reduce the required energy at excitation, which is ideal for those molecules with low laser damage threshold.
提出了一种改进的靶心纳米结构作为表面增强荧光的基底。通过时域有限差分法进行优化，在中间的纳米蝴蝶结周围的上下表面均设置了环形波纹。整个结构设计用于同时进行特定荧光的激发和发射过程，可极大地增强荧光强度（激发场增强35倍，辐射增强120倍，二者相互独立）。同时，它能够将远场发射能量限制在±3.5°的发散角内。这种基底的双共振增强和方向性使得荧光检测具有更高的灵敏度。此外，在发射时设计的共振和定向光控制可以有效降低激发所需的能量，这对于那些激光损伤阈值较低的分子来说是理想的。
