APL Photon. 1, 081301 (2016)

An ultrafast wireless communications link operating at a total data capacity rate 160 Gbit s−1 in the terahertz (THz) frequency band has been demonstrated by researchers from Denmark and China. The team used a coherent frequency comb and an optical local oscillator to create 8 carrier channels in the 300–500 GHz band, each channel was modulated at 20 Gbit s−1 and separated by 25 GHz. The THz beam was generated by a uni-travelling photodiode (UTC-PD) photomixing emitter and sent over free space for a distance of 50 cm, prior to being down-converted by a THz Schottky mixer receiver and the data channels demodulated. Analysis indicates that all 8 data channels operated with a bit-error-rate performance within the capabilities of forward-error correction, indicating the potential for free-space communication in the THz window at data rates beyond 100 Gbit s−1. According to the team, the reduction of THz phase noise by compensating the optical path difference for different channels was important to the success of the experiment.