Radiation Forces and Torque on Dielectric Janus Particles

Radiation forces and torques arising from light scattering on asymmetric particles enable precise optical manipulation in microfluidic and nanophotonic systems. In this study, we compute the radiation-induced drag, lift, and torque on dielectric Janus particles illuminated by a plane electromagnetic wave. We analyse how the orientation of the Janus interface and the dielectric contrast between the two hemispheres influence the particle's optomechanical response. Using the Lattice Boltzmann Method to solve Maxwell's equations, we quantify the spatial distribution of forces and torques resulting from light scattering. These optical effects are coupled with Stokes drag to compute and visualise the resulting trajectories of Janus particles under the combined influence of radiation pressure and viscous forces. This framework offers a systematic approach for tailoring optical forces on asymmetric dielectric particles, with potential applications in optical trapping, sorting, and the design of advanced photonic devices.