Extended Data Fig. 2: Experiment setup for 16-GHz microwave generation and characterization.
From: All-optical frequency division on-chip using a single laser

EDFA, erbium-doped fibre amplifier; WDM, wavelength division multiplexer. Two near-identical spiral resonators are used for OPO and soliton-comb generation, respectively. The output of the OPO chip is combined with the pump for the soliton chip via a fibre-based WDM to facilitate synchronization.