Orbital angular momentum channel monitoring of coaxially multiplexed vortices by diffraction pattern analysis.

We theoretically and experimentally demonstrate a scheme to monitor the weight of a single orbital angular momentum (OAM) channel for coaxial multiplexed optical vortices with large mode spacing. A specially designed holographic grating is illuminated by the incident multiplexed vortices first. Then the weight of each single OAM channel is obtained after analyzing the captured diffraction patterns. This work will find applications in domains where multiplexed optical vortices are of interest, such as the OAM-based data-transmission system, and so on.