Jović, D. Arsenović, D. Strinić, A. Belić, M. Petrović, M. Media 15: Counterpropagating optical vortices in photorefractive crystals Originally published in Optics Express on 13 June 2005 (oe-13-12-4379) Optics Express;13 June 2005;media;oe;vortice;photorefractive crystals;Counterpropagating 2005-06-13
    https://opticapublishing.figshare.com/articles/media/Media_15_Counterpropagating_optical_vortices_in_photorefractive_crystals/4932785
10.1364/OPEX.13.004379.m015