  The design and implementation of a multiplexed spiral phase mask in an
experimental optical tweezer setup are presented. This diffractive optical
element allows the generation of multiple concentric vortex beams with
independent topological charges. The generalization of the phase mask for
multiple concentric vortices is also shown. The design for a phase mask of two
multiplexed vortices with different topological charges is developed. We
experimentally show the transfer of angular momentum to the optically trapped
microparticles by enabling orbiting dynamics around the optical axis
independently within each vortex. The angular velocity of the confined
particles versus the optical power in the focal region is also discussed for
different combinations of topological charges.
