Fiber-wireless transmission system of 108 Gb/Ms data over 80 km fiber and 2 × 2 multiple-input multiple-output wireless links at 100 GHz W-band frequency

We experimentally demonstrate a seamlessly integrated fiber-wireless system that delivers a 108 Gb/Ms signal through 80 km fiber and 1 m wireless transport over free space at 100 GHz adopting polarization-divisionmultiplexing quadrature-phase-shift-keying (PDM-QPSK) modulation and heterodyning coherent detection. The X- and Y-polarization components of the optical PDM-QPSK baseband signal are simultaneously upconverted to 100 GHz wireless carrier by optical polarization-diversity heterodyne beating, and then independently transmitted and received by two pairs of transmitter and receiver antennas, which form a 2 × 2 multiple-input multipleoutput wireless link. At the wireless receiver, two-stage downconversion is performed firstly in the analog domain based on balanced mixer and sinusoidal radio frequency signal, and then in the digital domain based on digital signal processing (DSP). Polarization demultiplexing is realized by the constant modulus algorithm in the DSP part at the receiver. The bit-error ratio for the 108 Gb/Ms PDM-QPSK signal is less than the pre-forward-error-correction threshold of 3.8 × 10.3 after both 1 m wireless delivery at 100 GHz and 80 km single-mode fiber-28 transmission. To our knowledge, this is the first demonstration to realize 100 Gb/Ms signal delivery through both fiber and wireless links at 100 GHz.