Fig. 5: Simulated platicon switching dynamics and measured microwave phase noise spectra.

a LLE simulation of platicon’s optical power (blue curve) and repetition rate \({f}_{{\rm{r}}}\) (red curve) with increasing DFB laser frequency (black arrow). Discrete steps corresponding to different platicon states are numerically marked. b Simulated platicon spectra corresponding to the marked states in a. c Phase noise spectra of our \(10.7\,{\rm{GHz}}\) microwave (solid red line), the second harmonic (\(21.4\,{\rm{GHz}}\), dashed red line), and the third harmonic (\(32.1\,{\rm{GHz}}\), dashdot red line), in comparison with the spectra in ref. ⁵⁴ (green line), ref. ⁵ (orange line), and ref. ³⁶ (blue line), as well as the PNA floor (light dashed blue line) and shot noise floor (dashed black line). While we use an integrated PD chip, refs. ^5,36,54 use commercial, non-integrated PD via fiber connection. Inset is the power spectrum of the \(10.7\,{\rm{GHz}}\) microwave in our work. RBW, resolution bandwidth