Demonstration of 200-Gb/s PON With 37-dB/44-dB Power Budget Over 20-km SSMF/AR-HCF Based on a Deep-Learning-Enabled Optimal Direct-Detection Receiver

200-Gb/s passive optical network (PON) is regarded as a natural step for the next generation PON beyond 50-Gb/s line rate. Currently, the existing solutions include O-band intensity modulation-direct detection PON and C-band coherent PON. However, it is challenging to realize 200-Gb/s direct-detection PON in conventional C band at a low cost due to chromatic dispersion. In this paper, we propose a complex-valued double-sideband direct-detection (CV-DSB DD) PON architecture to approach the performance of coherent PON. Based on a single-wavelength and single-polarization deep-learning-enabled optimal direct-detection receiver with 28.125-GHz electrical bandwidth, we experimentally demonstrate a 50-GBaud 16-ary quadrature amplitude modulation (16-QAM) CV-DSB DD PON over 20-km standard single-mode fiber in conventional C band, with 15-dBm launch power and −22-dBm receiver sensitivity at a 15% soft-decision forward error correction (SD-FEC) threshold of 2×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup>. To the best of our knowledge, we achieve the highest optical power budget of 37 dB for 200-Gb/s direct-detection PON. Moreover, by leveraging the merit of ultra-low nonlinearity refractive index of the anti-resonant hollow-core fiber, we successfully demonstrate a 50-GBaud 16-QAM CV-DSB DD PON over 20-km self-developed anti-resonant hollow-core fiber with 23-dBm launch power and −21-dBm receiver sensitivity under the 15% SD-FEC threshold. The results indicate that we report a record optical power budget of 44 dB for 200-Gb/s PON so far according to the best of our knowledge.