Abstract We present a sub-terahertz (THz) wireless link using photonics-based ultra-low phase noise transmitter and receiver. The maximum data rate achieved below hard-decision forward error correction (HD-FEC) threshold by using on-line signal processing was 240 Gbit/s with 64 quadrature amplitude modulation (64QAM) at a single carrier frequency of 275 GHz. We also demonstrate successful 20-m transmission at a data rate of over-200 Gbit/s data rate. This is the highest single-channel performanc...