Trapping two types of particles by using a tightly focused radially polarized power-exponent-phase vortex beam.

We investigate the intensity of a radially polarized power-exponent-phase vortex (PEPV) beam focused by a high-numerical-aperture objective. A bright focal spot and a focal annulus with a dark core can be generated by changing the phase of the PEPV beam. The possibility of trapping a gold particle with the bright focal spot and trapping an air bubble with the focal annulus is discussed, and the force and trapping stability are calculated. It is shown that a tightly focused radially polarized PEPV beam is applicable to trapping two types of particles.