Propagation of Azimuthally Polarized Bessel-Gaussian Beam through Helical Axicon

Propagation properties of azimuthally polarized Bessel-Gaussian (APBG) beams with non-zero order through a helical axicon (HA) are theoretically investigated. The formula of APBG beams field in the focal region are derived by the vector diffraction theory. Numerical results illustrate that the beam and axicon parameters affect the intensity distribution in the focal region very considerably. Super-long transversely polarized focal depth with different shapes are obtained by choosing appropriate values of parameters. We also observed that a focal shift occurs which depends on both axicon parameter and numerical aperture. We expect that focusing APBG beams by HA can be used in optical trapping.