Focusing properties of vector vortex-bearing beams

Focusing properties of the vector vortex-bearing beams are investigated theoretically by vector diffraction theory. Simulation results show that the intensity distribution in focal region can be altered considerably by adjusting topological charge m and the numerical aperture (NA) of the focusing optical system. Focal pattern evolves from one focal spot to two overlapped intensity peaks. The two overlapped intensity peaks separate with increasing topological charge m, which leads to the focal splitting. It was found that evolution principle of focal pattern differs very remarkably with different numerical aperture of the focusing optical system. And focal split appears in focal evolution with different topological charge m in different numerical aperture of the focusing optical system. Results show that the topological charge of the vector vortex-bearing beams influences the focal intensity distribution considerably, and some novel focal patterns appear.

► The focal pattern evolution principle differs for different NA of the focusing optical system. ► Focal split appear with different NA topological charge in different of the focusing optical system. ► Focusing properties is affected not only by the helical phase structure but also the depolarization associated with a high NA objective.