Azimuthal and radial shaping of vortex beams generated in twisted nonlinear photonic crystals Shemer, Keren ; Voloch-Bloch, Noa ; Shapira, Asia ; Libster, Ana ; Juwiler, Irit ; Arie, Ady Abstract Publication: Optics Letters Pub Date: December 2013 DOI: 10.1364/OL.38.005470 Bibcode: 2013OptL...38.5470S