Broadband optical vortex beam generation using flat-surface nanostructured gradient index vortex phase masks

We developed a new kind of compact flat-surface nanostructured gradient index vortex phase masks, for effective generation of optical vortex beams in broadband infrared wavelength range. A low-cost nanotechnological material method was employed for this work. The binary structure component consists of 17557 nano-sized rods made of two lead-bismuth-gallium silicate glasses which were developed in-house. Those small rods are spatially arranged in such a way that, according to effective medium theory, the refractive index of this internal structure is constant in radial direction and linearly changes following azimuthal angle. Numerical results demonstrated that a broadband nanostructured vortex phase mask with a thickness of 19 μm can convert Gaussian beams into fundamental-charged vortex beams over 290 nm wavelength bandwidth from 1275 nm to 1565 nm. The results are in good agreement with experimental investigations conducted using three diode laser sources operating at 1310, 1550, and 1565 nm. The vortex beams generations are verified through their uniform doughnut-like intensity distributions, clear astigmatic transformation patterns, and spiral as well as fork-like interferograms. This new flat-surface component can be directly mounted to an optical fiber tip for simplifying vortex generator systems as well as easier manipulation of the generated optical vortex beams in three-dimensional space.The presented dataset includes: - image of the optimal structure of the phase element (Vortex.png) and the Vortex.csv file, with information about the arrangement, row by row, of rods made from two glasses in the hexagonal structure.To properly display the attached csv data is included Matlab script: ScriptDrawStructure.m. This script uses the Matlab function: DrawStructure.m- images (*.png) of intensity distributions registered during the experimental work.