Transversely polarized ultra-long optical needles generated by cylindrical polarized circular airy gaussian vortex beams

Abstract

We theoretically demonstrate a transversely polarized ultra-long optical needle with lateral width beyond diffraction limit generated by tight focusing of a cylindrical polarized circular Airy Gaussian vortex beam (CAiGVB). According to the calculation expression derived through the Richard–Wolf​ diffraction theory, the properties of optical needles are investigated in simulation in detail. The analysis reveals that the interaction between the vortex phase and the state of polarization of the CAiGVB through tight focusing results in the generation of the transversely polarized optical needles. The depth of the optical needle is strongly affected by the maximum position of the brightest ring, the optical distribution factor and the truncation factor of the CAiGVB. However, the lateral width of optical needle is only influenced by the maximum position of the brightest ring. The simulation results indicate that an optical needle of longitudinal length 38λ with lateral width of only 0.46λ can be achieved. To improve the intensity uniformity of longitudinal direction, a method of the combination of tight focusing with a binary phase element is used Such a transversely polarized optical needle has significant potential in atomic trapping and ultrahigh density magnetic storage.