200 Gbit/s/λ PDM-PAM-4 PON system based on intensity modulation and coherent detection

A low-complexity and cost-efficient coherent detection-based 100 Gb/s or beyond passive optical network (PON) has attracted a lot of attention in recent years, as this technology offers high receiver sensitivity, colorless frequency selectivity, and linear detection enabling channel impairment compensation in the digital domain. We experimentally demonstrate the first single-wavelength 200 Gb/s coherent PON over 20 km downstream transmission with polarization division multiplexed four-level pulsed amplitude modulation (PDM-PAM-4) signals in the C-band. The intensity modulator replaces the costly in-phase/quadrature modulator, and hardware-efficient carrier recovery technologies are used for recovery of PAM-4 symbols. By using optimized Nyquist pulse shaping, the transceiver bandwidth can be reduced to within 50 GHz. A maximum power budget of 32.5 dB can be achieved for 200 Gb/s/λ PDM-PAM-4 at a bit error rate of $ 1 \times 10^{ - 2}$ over 20 km fiber transmission. The possibility of a 200 Gb/s/λ PON is investigated using intensity modulation and coherent detection for the first time to our knowledge.