Photonics-aided 2 × 2 MIMO wireless terahertz-wave signal transmission system with optical polarization multiplexing

We experimentally demonstrate a photonics-aided 2 × 2 multiple-input multiple-output (MIMO) wireless transmission system at a terahertz-band (THz-band). In our demonstrated system, the generated 4-Gbaud polarization-division-multiplexing quadrature-phase-shift-keying (PDM-QPSK) signal at 450GHz by photonic remote heterodyning can be delivered over a 142-cm 2 × 2 MIMO wireless transmission link, with a bit-error ratio (BER) less than the hard-decision forward-error-correction (HD-FEC) threshold of 3.8 × 10⁻³. The further introduction of up to a 50-km single-mode fiber-28 (SMF-28) transmission causes a negligible power penalty. To the best of our knowledge, this is the first time a 2 × 2 MIMO wireless transmission of a polarization-multiplexing terahertz-wave (THz-wave) signal has been realized.