Multi-image transmission based on a multi-channel OAM-array-coded optical communication system using a designed Dammann grating and an integrated vortex grating.

Vortex beams (VBs) have the potential to support high-capacity optical communications. However, a typical VB carries only a single orbital angular momentum (OAM) in space, limiting its high-capacity communication. We propose controllably simultaneous generation of high-quality VB arrays with multiple OAMs, creating the independent multi-channel space in which the OAM mode can be flexibly manipulated at the corresponding spatial location. We then demonstrate a VB array-based multi-channel optical communication system combining a custom-designed Dammam grating and an integrated vortex grating, with the help of a designed single-input multiple-output deep learning recognition model. Experimental demonstration of the simultaneous transmission of four grayscale images was verified, with an average error rate of less than 0.003 without turbulence and 0.061 with turbulence. The proposed multi-channel method (multi-image transmission) can significantly increase the versatility of the VB array and further broaden its application in high-capacity optical communications.