title: Ultrasensitive size-selection of plasmonic nanoparticles by Fano interference optical force.
abstract: In this paper, we propose a solution for the ultrasensitive optical selection of plasmonic nanoparticles using Fano interference-induced scattering forces. Under a Gaussian beam excitation, the scattering of a plasmonic nanoparticle at its Fano resonance becomes strongly asymmetric in the lateral direction and consequently results in a net transverse scattering force, that is, Fano interference-induced force. The magnitude of this transverse scattering force is comparable with the gradient force in conventional optical manipulation experiments. More interestingly, the Fano scattering force is ultrasensitive to the particle size and excitation frequency due to the phase sensitivity of the interference between adjacent plasmon modes in the particle. Utilizing this distinct feature, we show the possibility of size-selective sorting of silver and gold nanoparticles with an accuracy of about ±10 nm and silica-gold core-shell nanoparticles with shell thickness down to several nanometers. These results would add to the toolbox of optical manipulation and fabrication.
authors.affiliation: Beijing Key Laboratory of Nano-Photonics and Nano-Structure (NPNS), Department of Physics, Capital Normal University , Beijing 100048, PR China.
authors.forename: Zhipeng
authors.initials: Z
authors.lastname: Li
authors.forename: Shunping
authors.initials: S
authors.lastname: Zhang
authors.forename: Lianming
authors.initials: L
authors.lastname: Tong
authors.forename: Peijie
authors.initials: P
authors.lastname: Wang
authors.forename: Bin
authors.initials: B
authors.lastname: Dong
authors.forename: Hongxing
authors.initials: H
authors.lastname: Xu