Demonstration of m-ary encoding/decoding using visible-light Bessel beams carrying orbital angular momentum (OAM) for free-space obstruction-free optical communications. - Jing Du 005; Shuihui Li; Yifan Zhao 003; Zhidan Xu; Long Zhu; Peng Zhou; Jun Liu 073; Jian Wang 060 (OFC, 2015)