Generation and Heterodyne Detection of >100-Gb/s $Q$ -Band PDM-64QAM mm-Wave Signal

We experimentally demonstrate a hardwareand spectral-efficient large-capacity single-carrier radio-overfiber system at Q-band (33-50 GHz), employing high-level polarization-division-multiplexing 64-ary quadrature-amplitudemodulation (PDM-64QAM) modulation and heterodyne coherent detection. In our demonstrated system, up to 10-GBd (120-Gb/s) PDM-64QAM vector millimeter-wave (mm-wave) signal at 37.5 GHz can be generated and delivered over 1-m wireless distance, with a bit-error ratio (BER) less than the hard-decision forward-error-correction (FEC) threshold of 3.8 × 10
^-3
. Our demonstrated system can also generate up to 16-GBd (192-Gb/s) PDM-64QAM vector mm-wave signal at 37.5 GHz, with a BER less than the soft-decision FEC threshold of 1 × 10
^-2
. During the receiver digital signal processing, the employment of largetap decision-directed least-mean-square equalization after carrier recovery significantly improves the system performance. To the best of our knowledge, this is the first time to demonstrate single-carrier PDM-64QAM modulated wireless mm-wave signal delivery.