Radiation Forces and Torques on Janus Cylinders

The interaction of electromagnetic waves with dielectric Janus particles gives rise to radiation forces and torques, governed by the dielectric properties, interface orientation, and the size-to-wavelength ratio. In this study, we employ the Lattice Boltzmann Method to compute the radiation-induced drag, lift, and torque on circular Janus cylinders when illuminated by a transverse magnetic polarized plane wave. We analyze both metallo-dielectric and dielectric Janus cylinders. For metallo-dielectric Janus cylinders, LBM predictions are validated against analytical results, showing excellent agreement in far-field bistatic scattering width, radiation force, and torque across a range of dielectric constants and interface orientations. Extending the study to dielectric Janus cylinders, we explore how the dielectric contrast and interface orientation shape the optomechanical response. Our findings show that radiation-induced forces and torques can be harnessed to drive and control the motion of dielectric Janus particles in optofluidic, active, and self-assembling systems.