Fig. 1. Principle of soliton reversible generation. (a) Intracavity power curve at pump forward tuning without auxiliary laser; the soliton range is invisible. (b) Intracavity power curve when the pump is forward tuned in the dual-laser system; the soliton steps are visible. (c) Intracavity backpropagation of the dual-laser system. (d) Schematic diagram of the backward tuning. States 1–3 show the changes in intracavity dynamics when the pump laser is tuned forward. States 3 and 4 show the changes in intracavity dynamics when the pump laser is tuned backward. State 5 shows the deterministic generation of DKSs by adjusting the auxiliary laser detuning. (e) Intracavity power curve when the pump is backward tuned in the dual-laser system, with soliton reversible generation and longer soliton steps.

Fig. 2. Schematic diagram of DKS comb generation experiments based on the auxiliary laser. CW, continuous wave; EDFA, erbium-doped fiber amplifier; FPC, fiber polarization controller; PD, photodiode; OSC, oscilloscope; ESA, electrical spectrum analyzer; OSA, optical spectrum analyzer.

Fig. 3. Backward tuning for DKS combs reversible generation. (a) Electric field traces of pump output when the pump laser is forward tuned and backward tuned. The inset is the 10 overlaid experimental traces of reversible generation of solitons of backward tuning under the same conditions. (b)–(i) Spectra of the pump output at different pump detuning states. (i) is the single DKS generated by backward tuning; the red line is the spectral envelope obtained by fitting the sech² function. Inset: the pulse time of the single DKS measured by the APE autocorrelator. (j) RF signals of multiple solitons and one soliton measured by the ESA.

Fig. 4. Electric field traces of pump output when the initial detuning of the auxiliary laser is inaccurate. The inset shows a magnified view of the forward tuning without soliton steps.

Fig. 5. Deterministic generation of multiple solitons by tuning the auxiliary laser while keeping the wavelength of the pump laser basically unchanged. The upper right corner shows the schematic diagram of the soliton distribution in the microresonator. (a) Five solitons. (b) Four solitons. (c) Three solitons. (d) Two solitons.