Free Space Vortex Light by Diffraction of a Bessel Beam From Optical Fiber

A free space vortex light generator is designed based on the diffraction of an optical Bessel beam. The Bessel beam propagating in a single mode fiber is modulated by a helical phase disk designed at the fiber end and gradually evolves to vortex light in free space. The properties of the generator such as operation wavelength range, polarization sensitivity, and fabrication tolerance are analyzed using finite-difference time-domain software. With the inherent advantage of the "nondiffraction" feature of the Bessel beam naturally obtained from an optical fiber, the proposed fiber vortex light generator would have potential applications in high-resolution imaging, particle trapping, manipulation, and so on.