Up to 94 GBd THP PAM-4 Transmission with 33 GHz Bandwidth Limitation

We demonstrate 94 GBd PAM-4 intensity-modulation direct-detection (IM/DD) transmission in a system with only 33 GHz bandwidth limited by a brick-wall filter of an 80 GSa/s ADC. A record faster-than-Nyquist rate of 42.4% is achieved based on Tomlinson-Harashima precoding.