Trapping of resonant metallic nanoparticles with engineered vectorial optical field

Abstract

Optical trapping and manipulation using focused laser beams has emerged as a powerful tool in the biological and physical sciences. However, scaling this technique to metallic nanoparticles remains challenging due to the strong scattering force and optical heating effect. In this work, we propose a novel strategy to optically trap metallic nanoparticles even under the resonant condition using engineered optical field. The distribution of the optical forces can be tailored through optimizing the spatial distribution of a vectorial optical illumination to favour the stable trapping of a variety of metallic nanoparticles under various conditions. It is shown that this optical tweezers has the ability of generating negative scattering force and supporting stable three-dimensional trapping for gold nanoparticles at resonance while avoiding trap destabilization due to optical overheating. The technique presented in this work offers a versatile solution for trapping metallic nanoparticles and may open up new avenues for optical manipulation.

Tailoring optical complex field with spiral blade plasmonic vortex lens

“…The OAM arises from the spatial structure of the optical field and has a value of lħ per photon ( l can take any integer value). In the past decade, optical complex fields with unconventional spatial distributions in terms of amplitude, polarization and phase are rapidly becoming a current trend due to the possibility of exploring the fundamental physics with numerous potential applications including optical tweezers, information storage, processing and transportation, microscopic and nanoscopic imaging, remote sensing, materials micromachining and processing, etc 2 3 4 5 6 . Among those optical complex fields, vortex beam is one specific case that is characterized by a helical wavefront along with an optical singularity in the center.…”

Trapping and manipulation of nanoparticles using multifocal optical vortex metalens

“…Different from dielectric ones, trapping plasmonic nanoparticles generally are considered difficult mostly due to the dominating scattering force. In order to increase the trapping efficiency of plasmonic nanoparticle, several methods have been proposed to decrease the magnitude of the scattering force or even reverse the direction of the scattering force to be against the power flow 12 , 13 . However, these methods involve the use of optical manipulation techniques to generate the required optical complex field, which are difficult to apply in practice.…”

“…Thanks to the advanced optical engineering, generation of optical fields with inhomogeneous spatial distribution in terms of phase, amplitude and polarization become possible, which are helpful to improve the performance of optical tweezers and realize novel optical micromanipulation techniques 6 – 9 . For example, negative scattering force has been reported for some Bessel beams 10 , 11 , enabling to trap plasmonic nanoparticle even under the resonant condition by tailoring the spatial distribution of the vectorial optical illumination 12 , 13 .…”

Vectorial optical fields: recent advances and future prospects

“…Interactions between vectorial optical fields with nanostructures have been utilized in semiconductor metrology [97] and nonlinear optical imaging [98]. Applications of vectorial optical fields in nanoparticle confinement and manipulation continue to draw increasing interests due to the fact that the use of vectorial optical fields could eventually enable us to customized the focal field distribution and tailor the optical force distributions to suit for specific needs of different applications [99][100][101]. Combined with the latest development in optical focal field engineering and interactions between vectorial optical fields and nanostructures, the research into spinorbit interactions (SOI) will inevitably lead to applications in advances optical imaging, sensing, photonic integrated circuitry and quantum information processing.…”