Radiation force of a self-focused vortex beam on Rayleigh particles

The radiation force of a partially coherent self-focusing vortex beam on Rayleigh particles is studied in this paper. According to the generalized Huygens-Fresnel principle and Rayleigh scattering theory, the effects of two main parameters of the beam, namely relative coherence length and non-trivial phase factor, on the self-focusing characteristics and radiation force are respectively researched. We have also conducted a brief analysis of the stability of particle capture using this self-focusing vortex beam. It has been found that changing the values of such parameters can flexibly regulate the self-focusing effect of the beam on propagation so as to effectively adjust the magnitude of the radiation force and trapping range. The results show that such beams can be used to trap and manipulate particles without using a focusing lens. In addition, this beam is able to capture two different refractive index particles, that is, high refractive index particles are captured near the focus, and low refractive index particles are captured on the z-axis. The research results establish a theoretical basis for the application of this novel partially coherent self-focusing vortex beams in optical tweezers technology. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement