Nowadays, vortex beams (VBs), carrying orbital angular momentum (OAM), have been known as the hot spots and shown great potential in various fields such as optical micro-manipulation, optical sensors, optical transmission, optical lasers, and amplifiers. In 1992, Allen et al. indicated that for beams with helical phase fronts of the OAM in the propagation direction has the discrete values of per photon, where is the reduced Planck constant, and is usually an integer that represents the topological charge (TC), whose sign indicates the direction of the phase spiral. In theory, the VBs with different OAM modes are mutually orthogonal, and their intensity distribution presents unique “doughnut” shapes due to phase uncertainty at the beam cross section. The discovery of optical vortices carrying OAM has accelerated progress in many research areas. Especially in optical communications, VBs are of great potential in increasing capacity and modulation ability by providing additional physical dimension. By multiplexing VBs, the transmission rate of Tbit/s is realized in free-space optical (FSO) communication[6,7]. Also, further studies have shown that hybrid multiplexing of OAM and other dimensions can achieve communication capacity close to Pbit/s. However, the OAM shift keying communication, which encodes digital signals to OAM modes, is severely hampered because the locking effective detection methods can hardly adapt to the fast switching modes. Moreover, the VBs are susceptible to atmospheric turbulence (AT), which may cause wavefront distortion and lead to mode diffusion. Hence, fast and high-accuracy OAM mode recognition is a challenge in the practical application of VBs.