Multi-beam vortex generation induced by the non-linear optical anisotropy of graphene Luis Plaja, Ana García-Cabrera, Roberto Boyero-García, Óscar Zurrón, Julio San Román and Carlos Hernández-García EPJ Web Conf., 266 (2022) 08012 Published online: 13 October 2022 DOI: 10.1051/epjconf/202226608012