Fig. 2. Soliton crystal generation.

To generate a soliton crystal, a laser is slowly tuned from the red side of a resonance to a pre-set wavelength. a A primary comb (Turing pattern) is initially generated as the laser is tuned into resonance with the ring. b Spectrum of the soliton crystal oscillation state used for experiments. The state had a characteristic ‘scalloped’ micro-comb spectrum, corresponding to the single temporal defect crystal state illustrated over the ring. At the pre-set wavelength, a soliton crystal forms, with spectral features based around the primary comb lines. The state that we use provides comb lines over most of the optical communications C-band. c Soliton crystal comb line power difference for 10 independent crystal generation instances (different symbols indicate distinct generation instances). Comb line powers remain within ± 0.9 dB of the initial spectrum, indicating reliable generation of the desired soliton crystal state.