Dynamical characteristics of tightly focused circularly polarized modulated autofocusing vortex beams and their optimized trapping performance for chiral nanoparticles.

Abstract

By combining the improved properties of the Bessel modulated autofocusing beam [Phys. Rev. A104, 043524 (2021)PLRAAN1050-294710.1103/PhysRevA.104.043524] with the influence of the canonical optical vortex, we study the dynamical characteristics of tightly focused circularly polarized modulated autofocusing vortex beams (CPMAVBs) and their performance in trapping chiral nanoparticles. We find that the distributions of the beam's intensity and dynamical characteristics depend on the value of the topological charge carried by the beam. Moreover, CPMAVBs exhibit higher peak intensity and superior dynamical characteristics compared to the circularly polarized circular Airy vortex beam (CPCAVB), despite the attenuation of the optimized modulation of the Bessel function due to the presence of vortex. Building on these excellent properties, CPMAVB demonstrates greater radial optical force (transverse trapping potential) and azimuthal optical force (orbital rotation frequency) for trapping chiral nanoparticles compared to CPCAVB. We also discuss the effects of input power and particle radius on the manipulation capabilities of CPMAVB and CPCAVB. Our results provide insights into the dynamical characteristics of the CPMAVB and may open new possibilities for the optical manipulation of chiral particles using this structured beam.