A pure longitudinal magnetization induced by 4π tightly focusing of two linearly polarized vortex beams

In this paper, according to the inverse Faraday effect, a pure longitudinal magnetization field induced by 4π tightly focusing of two linearly polarized vortex beams (LPVBs) is investigated. We find that the orbital angular momentum (OAM) of these two LPVBs could be transformed into spin angular momentum in the tightly focusing condition, and a longitudinal magnetization with purity of 100% is generated, if the topological charges of the two counterpropagating LPVBs are two identical odd numbers. In addition, the distribution and strength of induced longitudinal magnetization could be regulated by turning the OAM of the two counterpropagating LPVBs and numerical aperture of the two focal lenses, respectively. Besides, the local polarization states of the light field and a three-dimensional magnetization array in the focal region is surveyed. We believe that this 4π setup of generating a pure longitudinal magnetization could potentially be used to the field of storage technology especially for the using of massively parallelized all-optical magnetic recording.