Real-time reception of 106 Gbps PAM-4 transmission over an 80 km SSMF link enabled by CD pre-compensation

In this study, we report, to the best of our knowledge, the first experimental demonstration of the real-time reception of a 106 Gbps PAM-4 transmission over an 80 km dispersion uncompensated standard single-mode fiber (SSMF) link. In the transmitter, a chromatic dispersion (CD) pre-compensation, aided by an optical IQ modulator, is implemented. The optimization guideline of driver signal amplitudes and bias voltages is proposed to enable optimal CD pre-compensation. In the receiver, a real-time PAM-4 module including simple feed-forward equalization (FFE) is used. After the transmission, the required optical signal-to-noise ratio (OSNR) at a bit error rate (BER) below 3.8 × 10^-3 is determined to be 35 dB for 106 Gbps PAM-4 signals. The better BER of 6.9 × 10^-4 is achieved successfully compared to the previously reported off-line reception. The demonstration confirms the feasibility of 80 km DCI based on CD pre-compensation under real-time reception.