Optical amplifier-free 100 Gbaud PAM-4 transmission over 10 km SSMF based on O-band SiP transceiver

The O-band operation becomes an ideal choice for the high-speed intensity modulation direct detection (IM-DD) transmission, benefitting from both a low CD and low-cost transceiver. Here, we explore the incorporation of both transmitter-side digital pre-emphasis and various receiver-side digital equalizers, in order to effectively deal with the severe inter-symbol interference (ISI) arising in the bandwidth constraint of O-band silicon photonic (SiP) transceiver and various transmission impairments after the fiber optical transmission. We experimentally evaluate the performance of various digital equalizers, including feed-forward equalizer (FFE), decision-feedback equalizer (DFE), Volterra feed-forward equalizer (VFFE), and Volterra decision-feedback equalizer (VDFE), when the pre-emphasis of SiP transceiver with a 10dB bandwidth of 21 GHz is implemented. Finally, we successfully demonstrate the optical amplifier-free 100 Gbaud PAM-4 signals transmission over 10 km SSMF, when the taps of VDFE are optimized, for the purpose of solving the trade-off between the implementation complexity and transmission performance.