405-GBd OOK and 201-GBd PAM-4 IM/DD Optics at Record Faster-Than-Nyquist Ratios of 226.6% and 62.1% Enabled by Advanced Noise Whitening

We experimentally demonstrate 405-GBd OOK and 201-GBd PAM-4 signaling in an intensity modulation and direct detection system with a 62-GHz brick-wall bandwidth. Record faster-than-Nyquist ratios of 226.6% and 62.1% are successfully achieved for OOK and PAM-4 modulations, enabled by the proposed gradient-decent noise whitening technique.