Programmable Multiple-Input–Multiple-Output Silicon-Photonics Processor for Optical Wireless Communications

Optical wireless communication (OWC) is one of the potential candidates to address the bandwidth limitation issue in 6G networks and satellite laser communications. Mode division multiplexing (MDM) can further increase the OWC transmission capacity by utilizing many different orthogonal modes for carrying data streams. However, in MDM transmission, modes may partially scatter to other modes during the transmission of the OWC with atmospheric turbulences, leading to the channel crosstalk. To accommodate this crosstalk issue, multiple-input–multiple-output (MIMO) techniques could be used. Here, we evaluate the performance of the optical MIMO processor in an MDM OWC system. Three aspects of the optical MIMO processor will be considered: (Exp. A) the MIMO performance characterization, (Exp. B) the atmospheric turbulence resiliency evaluation, and (Exp. C) the high-speed data transmission. For the first topic, we characterize three operation regimes wherein different channel extinction ratios (ERs) could be attained. If the initial modified average ERs are higher than 3.5 dB, we can realize >20 dB final ERs. For the second topic, the experimental results indicate that the processor can endure up to the middle turbulence without affecting system performances. Finally, we will show that with our MIMO processor, we can obtain record ∼45 Gbps data transmission per mode from an initially nontransmissible channel.