High-precision clock date recovery for optical wireless communications using orbital-angular-momentum-based mode division multiplexing.

In this Letter, we explore the potential of the application of clock data recovery for the implementation of real-time optical wireless communications (OWCs) employing orbital angular momentum (OAM)-based mode division multiplexing (MDM). We experimentally demonstrate a 3-mode multiplexed optical wireless link with a sum rate of 60 Gbps, in which the time synchronization of different channels is realized by the proposed modified digital feedback clock recovery based on the Gardner algorithm. The experimental results show that high-precision channel synchronization with a low timing error can be achieved, and the bit-error rate of all channels can drop below 7% of the hard-decision forward error correction (HD-FEC) limit of 3.8 × 10, which indicates that clock data recovery can potentially provide the implementation of real-time OWCs using OAM-based MDM.