New method for development of fused silica fibres with freeform nanostructured gradient index core

We present a new type of gradient index fused silica fibre with nanostructured core. A gradient index core is obtained by means of arbitrary distribution of two types of subwavelength glass rods. The proposed method allows to obtain arbitrary gradient distribution not limited to a circular symmetry as in standard gradient index fibers. We have developed a proof of concept fibre and show a very good match between design and the measured properties of the fibre.