Plasmonic Dipole and Quadrupole Scattering Modes Determine Optical Trapping, Optical Binding, and Swarming of Gold Nanoparticles

Abstract

Laser trapping at an interface provides a unique platform for assembling novel multiparticle-based optical matter that extends well beyond the irradiated area. Optical binding, resulting from the resonantly scattered photons by gold nanoparticles through the dipolar scattering mode, serves as the primary force for supporting the cohesion of the particles in these optically induced assemblies, which is interpreted in view of the formation of an optical binding network. Unfortunately, the dipole scattering mode is restricted to a narrow range of experimental conditions, limiting its use to specific trapping laser wavelengths and particle sizes. To address this limitation, exploring higher multipole scattering modes, such as the quadrupole, could provide a broader range of experimental conditions. In this work, we will describe how the higher quadrupole scattering mode influences the formation of optical binding and the possibility of extending the optical potential outside the irradiated area for constructing large optically induced assemblies.

Photovoltaic Rotation and Transportation of a Fragile Fluorescent Microrod Toward Assembling a Tunable Light-Source System

“…Rotation and transportation of micro/nanorods under external fields are fundamental for many optical, chemical, and biological operations , and thus important to a diversity of applications, such as advanced micro-electro-mechanical System (MEMS) assembly, − targeted drug delivery, , and precise subcellular surgery. , To achieve continuous motion of micro/nanorods, the energy of the capillary interaction, chemical, optical, ,,,,,,− acoustic, , magnetic, , and electric field − has to be converted into the mechanical work and propel the micro/nanorods. , A few strategies have been proposed to generate a stable torque on micro- and nanorods for their persistent rotational motion. Under an alternating current (AC) electrical field, micro/nanorods subjected to an electrical torque can align in the direction of the field, thus enabling the micro/nanorods in any prescribed orientation. − However, applying the AC electrical field relies on the fabrication of ingenious patterned electrodes on a microscale, with little possibility to adapt to different scenarios.…”