Probabilistic Shaping for PAM-8 Optical Ethernet Systems

A performance comparison of probabilistically shaped (PS) pulse amplitude modulation (PAM)-8 and uniform PAM-8 is performed in the context of 168 Gb/s intensity modulation and direct detect (IMDD) optical Ethernet system. PS-PAM-8 provides gain in terms of the optical signal-to-noise ratio of about 1.2 dB in the back-to-back system, and an increase of more than 15% in transmission reach at the 20% low-density parity-check (LDPC) soft decision forward error correction (FEC) threshold.