120 Gbit/s PDM-16QAM terahertz signal over 850 m using 2 × 2 MIMO links and advanced DSPs

The wireless range and data capacity of photonics terahertz (THz) communication systems above 300 GHz are limited by outdoor environmental challenges, including high atmospheric attenuation, water absorption, and efficiency limitations of optical-to-electrical conversion. In this Letter, we have showcased a dual-channel 2 × 2 multiple-input multiple-output (MIMO) system achieving a record 120 Gbit/s polarization-division multiplexing 16-ary quadrature amplitude modulation (PDM-16QAM) signal delivery over a wireless distance of 850 m at 300 GHz based on polarization multiplexing and advanced digital signal processing (DSP) technology. This demonstrates the largest rate-distance (R-D) product of 88,655 Gbit/s*m globally. Our work marks a significant step toward achieving high-capacity (over 100 Gbit/s) long-distance (kilometer-level) THz-wave communication. These research results are expected to serve as a low-cost and basic communication system technology for promising backhaul wireless communications in the 6G era.