Fig. 2
From: High-order coherent communications using mode-locked dark-pulse Kerr combs from microresonators

Transmitter description. a Schematic of the transmitter. WSS wavelength-selective switch, AWG arbitrary waveform generator. b Optical spectrum after pump line attenuation and the single-stage amplifier. The 20 lines of interest all have an OSNR of 35 dB or more. c Optical spectrum of the WDM signal before being sent to the link with all channels having above 33 dB of OSNR