Fig. 1. Evolution process of optical frequency combs based on forward tuning principle. (a) Simulation result of microcavity power transmission spectrum based on the normalized LLE; (b) time domain waveforms of Turing state, chaotic state, and soliton; (c) spectra distributions of Turing state, chaotic state, and soliton

Fig. 2. Experimental transmission spectra and regulatory characteristic parameters during the forward tuning. (a) Microcavity transmission spectrum and periodic PZT sweep voltage; (b) normalized collected voltage values of microcavity power under one forward sweep; (c) existence scopes and switching conditions of normalized mean and normalized peak-to-peak collected voltage values for output power under different optical comb states

Fig. 3. Experimental transmission spectra of reverse tuning and spectra distribution of soliton state optical frequency combs. (a) Experimental microcavity transmission spectrum of reverse tuning; (b) linear relationship between soliton number and detector voltage; spectra distribution under soliton number of (c1) 4, (c2) 3, (c3) 2, (c4) 1 during reverse tuning process; (c5) local experimental spectrum of single soliton state

Fig. 4. Self-starting experimental device for optical frequency comb

Fig. 5. Flowchart of FPGA autonomous control for generating optical frequency combs of arbitrary states

Fig. 6. Self-starting prototype of microcavity optical frequency combs. (a) Interior first layer; (b) interior second layer; (c) complete casing

Fig. 7. Self-starting results of optical frequency combs in different states. Distributions of experimental spectra for (a1) Turing state, (a2) chaotic state, (a3) multisoliton state, (a4) single soliton state; detector collected voltages during the regulation process of optical frequency combs in (b1) Turing state, (b2) chaotic state, (b3) multisoliton state, (b4) single soliton state