Hybrid coding method of multiple orbital angular momentum states based on the inherent orthogonality

We put forward a hybrid coding method of multiple orbital angular momentum (OAM) states based on the inherent orthogonality. Theoretical analysis shows this new coding method can tremendously improve the coding efficiency compared to the conventional way, and the OAM mode can be extended to all the transverse orthographic modes such as Bessel beams or Laguerre-Gauss modes. We also present a typical scheme to achieve the encoding of hybrid OAM states based on a concentric ring resonator array. We further suggest a digital device and a phase hologram pattern to decode the hybrid OAM states.