Optical forces and optical force categorizations on small magnetodielectric particles in the framework of generalized Lorenz-Mie theory

A previous study has been devoted to the case of optical forces exerted on Rayleigh particles in the framework of generalized Lorenz-Mie theory (GLMT). This study is here extended to the case of small magnetodielectric particles which are characterized by their electric and magnetic Mie coefficients a(1) and b(1) respectively. A partition of optical forces between incident-scattered mixed terms and recoil terms has been established in GLMT since more than three decades. This partition is here complemented by another partition between gradient, scattering and non-standard forces. The relationship between these non-standard forces and curl forces exhibited in the framework of a dipole theory is emphasized. The case of Rayleigh particles (more generally of electric dipolar particles) previously published in the GLMT-framework is recovered as a special case of the case of small magnetodielectric particles discussed in the present paper. The case of illumination by plane waves furthermore provides complementary insights on the behavior of non-standard forces. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study extends the previous research on optical forces exerted on Rayleigh particles to the case of small magnetodielectric particles. It introduces a partition between gradient, scattering, and non-standard forces and emphasizes the relationship between these non-standard forces and curl forces in the framework of a dipole theory.