Optical Trapping Based On Surface Plasmon Effect Of Triangular Silver Nanoplates

The surface plasmon of metal nanoparticles is a phenomenon in which free electrons on the metal surface resonate with incident photons and absorb photons to generate collective oscillation of electrons.The surface plasmon field excited by metal nanoparticles tends to be locally within a few tens of nanometers of the interface,resulting in a strong local electromagnetic field.This electromagnetic field enhancement effect in the nanoscale range produces a very strong gradient force,and its application to the optical trapping field can significantly improve the trapping accuracy and stability.Compared with traditional isotropic nanoparticles,the anisotropic structure of triangular nanopaltes provides stronger local electromagnetic field effect and adjustable localized surface plasmon effect.Therefore,this paper will construct triangular silver nanoplates with different structures.Based on the optical trapping properties of its surface plasmons.The FDTD Solution software was used to construct the monomer and multimer model of triangular silver nanoplates,and the linear polarization plane light incidence was selected.The three-dimensional electromagnetic field distribution of different structures of triangular silver nanoplates,the optical force distribution of the microspheres at different positions of the electromagnetic field and the light potential trap were studied.distributed.For the triangular plate monomer,the polarization of the plasmon electromagnetic field on the surface of the triangular silver nanoplates is controlled by changing the polarization direction of the incident light.At the same time,by changing the curvature of the apex angle of the triangular plate,it is proved that the triangular plate structure has a stronger local field than the disk structure.And the stable trapping of the microspheres in the surface plasmon field generated by the triangular silver nanoplates monomer is realized.For the triangular silver nanoplates polymer,the local electromagnetic field is further enhanced by the coupling effect of the surface plasmon.At the same time,by changing the spacing between the apex angles of the triangle,the smaller the apex spacing of the polymer is,the coupling effect is proved.The stronger the sex,the stronger the local electromagnetic field generated and the better the stability of the trapping microspheres.A special micro-nano array structure was constructed by using a triangular plate.The electric field and phase distribution of the plasmon on the surface of the triangular plate tetramer and the circular array structure were studied by selecting the circularly polarized plane light and the circularly polarized vortex light incident.The distribution of the center vortex field is realized by the incident of circularly polarized plane light.At the same time,the center electric field focusing of the array is realized when the circularly polarized vortex light is incident.This study can provide ideas for further enhancing the surface plasmon optical trapping.