Optical orbital-angular-momentum-multiplexed data transmission under high scattering

Multiplexing multiple orbital angular momentum (OAM) channels enables high-capacity optical communication. However, optical scattering from ambient microparticles in the atmosphere or mode coupling in optical fibers significantly decreases the orthogonality between OAM channels for demultiplexing and eventually increases crosstalk in communication. Here, we propose a novel scattering-matrix-assisted retrieval technique (SMART) to demultiplex OAM channels from highly scattered optical fields and achieve an experimental crosstalk of –13.8 dB in the parallel sorting of 24 OAM channels after passing through a scattering medium. The SMART is implemented in a self-built data transmission system that employs a digital micromirror device to encode OAM channels and realize reference-free calibration simultaneously, thereby enabling a high tolerance to misalignment. We successfully demonstrate high-fidelity transmission of both gray and color images under scattering conditions at an error rate of <0.08%. This technique might open the door to high-performance optical communication in turbulent environments.Recovering scattered data from twisted lightTwisted light beams can be made to transmit higher quality data by decoding the information present in the ‘speckle patterns’ that arise when they pass through scattering media. Lei Gong of the University of Science and Technology of China and colleagues developed the ‘scattering-matrix-assisted retrieval technique’ (SMART) to recover scattered data from multiplexed multiple orbital angular momentum (OAM) channels. These multiple twisting light beams have the potential to carry unlimited data channels, but light scattering, caused by micro-particles in the atmosphere or by energy transfer between channels, reduces data quality. The SMART platform allowed high-fidelity transmission of images, reducing the error rate by 21 times compared to previous reports. Improvements on the technique could facilitate the transfer of high quality optical data in harsh atmospheric or underwater conditions.