Investigation of the polarization-dependent optical force in optical tweezers by using generalized Lorenz-Mie theory

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’s 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 in the presence of dielectric spheres of selected diameters ranging from the Rayleigh scattering regime to the Mie scattering regime.