Fig. 3: Soliton microcombs driven by optical pulses.
From: Advances in resonator-based Kerr frequency combs with high conversion efficiencies
a Principle of continuous-wave-driven soliton frequency combs. A DKS propagates with a roundtrip time defined by the resonator’s inverse FSR while being supported by the resonant enhanced CW background. b Principle of pulse-driven soliton frequency combs. Stable solitons form atop the optical pulse with a repetition rate that coincides with the resonator’s FSR. c Resonator transmission trace obtained when the central driving mode scans across a resonance for an optimized pulse repetition rate. d Contour plot of the transmission showing soliton step existing over a wide (100 kHz) interval of repetition rate. e Optical spectrum of a single soliton driven by a pulse with a duration of 2.1 ps (which corresponds to the yellow spectrum in the frequency ___domain). The sech2-envelope fit (red) corresponds to a soliton pulse duration of 137 fs (the inset on the left). The inset on the right shows a magnified view of the spectrum in a 1 nm range. The green spectra show the transmission spectra of the bandpass filters (BPF 1 and 2) used for beatnote detection. Images are adapted with permission from ref. 50. Copyright 2017 Springer Nature Limited.
