Open AccessCircular nanocavity substrate assisted plasmonic tip for its enhancement in nanofocusing and optical trapping
Author(s) -
Fanfan Lu,
Wending Zhang,
Lixun Sun,
Ting Mei,
Xiaocong Yuan
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.441689
Subject(s) - plasmon , materials science , optical tweezers , electric field , optics , optoelectronics , raman spectroscopy , substrate (aquarium) , optical force , surface enhanced raman spectroscopy , tweezers , trapping , dielectric , surface plasmon , nanoparticle , nanotechnology , raman scattering , physics , ecology , oceanography , quantum mechanics , biology , geology
Plasmonic tip nanofocusing has widely been applied in tip-enhanced Raman spectroscopy, optical trapping, nonlinear optics, and super-resolution imaging due to its capability of high local field enhancement. In this work, a substrate with a circular nanocavity is proposed to enhance the nanofocusing and optical trapping characteristics of the plasmonic tip. Under axial illumination of a tightly focused radial polarized beam, the circular nanohole etched on a metallic substrate can form a nanocavity to induce an interference effect and further enhance the electric field intensity. When a plasmonic tip is placed closely above such a substrate, the electric field intensity of the gap-plasmon mode can further be improved, which is 10 folds stronger than that of the conventional gap-plasmon mode. Further analysis reveals that the enhanced gap-plasmon mode can significantly strengthen the optical force exerted on a nanoparticle and stably trap a 4-nm-diameter dielectric nanoparticle. Our proposed method can improve the performance of tip-enhanced spectroscopy, plasmonic tweezers and extend their applications. We anticipate that our methods allow simultaneously manipulating and characterizing single nanoparticles in-situ.