Investigation of Polarization-Dependent Optical Force in Optical Tweezers using Generalized Lorenz-Mie Theory

TL;DR

This paper numerically investigates how the polarization of a focused laser beam affects the electromagnetic field distribution and optical force asymmetry in optical tweezers, considering different sphere sizes from Rayleigh to Mie regimes.

Contribution

It introduces a detailed numerical analysis of polarization-dependent optical forces in optical tweezers using generalized Lorenz-Mie theory, highlighting the effects of electromagnetic field redistribution.

Findings

Polarization influences trap stiffness asymmetry.

Field distribution varies with input polarization.

Force symmetry changes with sphere size.

Abstract

In vectorial diffraction theory, tight focusing of a linearly polarized laser beam produces an anisotropic field distribution around the focal plane. We present a numerical investigation of the electromagnetic field distribution of a focused beam in terms of the input beam polarization state and the associated effects on the trap stiffness asymmetry of optical tweezers. We also explore the symmetry change of a polarization-dependent optical force due to the electromagnetic field redistribution by the presence of dielectric spheres of selected diameters ranging from the Rayleigh scattering regime to the Mie scattering regime.