Galaxy-Shaped Vortex Surface Relief Formation by Illumination of Orthogonal Laguerre-Gaussian Modes

Surface relief formation in azo-polymers has been attracting much interest in a myriad of fields, such as rewritable optical data storages [1]. In recent year, it has been discovered that an optical vortex with orbital angular momentum (OAM) assigned by a topological charge $\ell$ twists the irradiated azopolymer films to fabricate nano/micron-scale single-armed chiral surface reliefs, thereby enabling the development of high capacity optical data storages with a new freedom of chirality [2]–[4]. However, even using higher-order optical vortices with $\vert \ell\vert \geq 2$ , all of the fabricated surface reliefs are always single-armed.