Efficient sorting for an orbital angular momentum multiplexing communication link based on a digital micromirror device and a diffuser

Efficient sorting multiple orbital angular momentum (OAM) spatial modes is a significant step in OAM multiplexing communications. Recently, wavefront shaping (WS) techniques have been implemented to manipulate light scattering through a diffuser. We reported a novel scheme for sorting multiplexed OAM modes faster and more accurately, using the complex amplitude WS based on a digital micromirror device (DMD) through a diffuser to shape the full field (phase and amplitude) of the OAM modes. In this study, we simulate this complex sorter for demultiplexing multiple modes and make a performance comparison with the previous sorter using the phase-only WS. Our results showed that for arbitrary two multiplexed modes, the sorter could achieve a high detection probability of more than 0.99. As the number of the multiplexed modes increases, the detection probability decreases to ∼0.82 when sorting seven modes, which contrasts the ∼0.71 of the phase-only sorters. We also experimentally verified the feasibility, that for arbitrary two modes, the sorter could reach a high detection probability of more than 0.99, and the complex sorter is capable of higher detection probability than the phase-only sorter under the same conditions. Hence, we anticipate that this sorter may potentially be demultiplexing multiple OAM spatial modes efficiently and quickly.