Towards high spectral efficiency UDWDM-PON based on the simplified coherent reception of pulsed shaped PAM-4 signals

Abstract

Enhancing spectral efficiency (SE) of ultra-dense wavelength division multiplexing passive optical network (UDWDM-PON) is vital to providing broadband access for massive users. Here, we experimentally demonstrate a high SE UDWDM-PON in the C-band, based on the simplified coherent reception of 10 Gb/s 4-level pulse-amplitude modulation (PAM-4) signals. We investigate the WDM signal reception by mathematical derivation and propose to enhance the SE by adopting both intradyne detection and pulse shaping techniques. Then, both approaches are numerically evaluated, with an identification that there occurs a trade-off between SE and power budget improvements. Finally, we experimentally achieve a SE of 0.83 (bit/s)/Hz and a power budget of 25 dB for a proof-of-concept 3 × 10 Gb/s PAM-4 downstream transmission over 20 km standard single mode fiber (SSMF).