The physical origins of the transverse optical binding force and torque beyond the Rayleigh approximation have not been clearly expressed to date. Here, we present analytical expressions of the force and torque for a dual dipolar dielectric dimer illuminated by a plane wave propagating perpendicularly to the dimer axis. Using this analytical model, we explore the roles of the hybridized electric dipolar, magnetic dipolar, and electric-magnetic dipolar coupling interactions in the total force and torque on the particles. We find significant departures from the predictions of the Rayleigh approximation, particularly for high-refractive-index particles, where the force is governed by the magnetic interaction. This results in an enhancement of the dimer stability by one to four orders of magnitude compared to the predictions of the Rayleigh approximation. For the case of torque, this is dominated by the coupling interaction and increases by an order of magnitude. Our results will help to guide future experimental work in optical binding of high-refractive-index dielectric particles.
Bibliographical noteFunding Information:
This work was supported by the National Key R&D Program of China (Grant No. 2017YFA0303400) and the Postgraduate Education Reform Project of Tongji University (Grant No. 2018GH103). K.D. acknowledges support of the UK Engineering and Physical Sciences Research Council (Grant No. EP/P030017/1).
© 2021 American Physical Society.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics