High-speed spatial light modulation enabling 25-Gbit/s twisted light encoding/decoding and 260-m security free-space data transmission.

Spatial domain of light beam is an important degree of freedom to be extensively explored. As a set of spatial domains, twisted lights have some natural properties such as orthogonality and security, providing great potentials in optical communications especially for data encoding/decoding. However, the speed of traditional spatial light modulators has always been criticized. Here we present a hundred-meter security free-space data transmission based on high-speed spatial light modulation by exploiting temporal-to-spatial domain mapping. We demonstrate 25-Gbit/s twisted light encoding/decoding and 260-m security free-space data transmission in the experiment. The encoding/decoding link will lead to 3-dB improvement in bit error rate (BER) performance compared with a single channel in theory and ∼1-dB optical signal-to-noise ratio (OSNR) penalty at the forward error correction (FEC) threshold of 3.8e-3 in practice. The experiment results also show favorable security performance of the proposed encoding/decoding link system.