Generation of Multi-Mode OAM Waves Through Programable 2-Bit Digital Coding Metasurfaces. - Xudong Bai; Fanwei Kong; Yunzhuo Song; Shengyang Xu; Yanting Lv; Anjie Cao; Chong He; Weiren Zhu; Xianling Liang; Ronghong Jin (ICC Workshops, 2019)