All-fiber nanostructured gradient optics vortex beam converter

•Compact all-fiber converter generates a high quality focused vortex beam without support of any external optical elements•Generated vortex beam has low divergence and long working distance•A nanostructured microlens allows controlling size and position of the focused vortex beam while its beam quality is maintained•Performance of sequential use of nanostructured gradient index micro-components and fiber optics is verified experimentally