Modeling Realistic Dynamics of Nanoparticle Dimers for Magneto-Optical Matter

Abstract

Traditional approaches to optical matter often involve complex illumination fields with costly and unstable setups, requiring strong gradient forces, high-intensity laser spots that could harm samples, and substrate support. For binding, attractive inter-particle forces may not be sufficient to assemble systems due to unbalanced components such as centrifugal forces or collisions. In previous work, magneto-optical nanoparticles illuminated with two counter-propagating circularly polarized waves were optically bound under quasi-static conditions. However, the dynamics of such nano systems were not thoroughly considered. Here, a general framework to study magneto-optical (MO) matter is introduced, controllable by static magnetic fields. Dynamic binding between two n-doped InSb nanoparticles, which exhibit surface plasmons at THz frequencies, is recreated. Additionally, the reported examples may represent a novel approach of low-energy illumination sources without gradient components. This numerical framework, grounded in Langevin dynamics and realistic collision phenomena, serves as a robust and universal tool for exploring various optomechanical designs. The impact of thermal noise, collision types, initial conditions, and resonance excitation on a dimer system is examined. Dimers tuned initially at magneto-optical resonance can bind in stable, average positions even when particle-particle collisions are present. The current methodology provides essential knowledge for studying optical binding and the dynamics of any small-scale cluster of interacting sub-units.