Fig. 1. The influences of thermal effects on soliton formation and auxiliary laser assisted tuning method. (a) For strong thermal effects of ζ = −1 × 10⁴ (Ws)⁻¹, intracavity energy evolution reflects soliton annihilation or in chaotic regime. Different color represents distinct microcomb routes and determined by intracavity energy instability. (b) For weak thermal effect of ζ = −5 × 10³ (Ws)⁻¹ solitons can always survive in all 20 scans. Calculated temporal profile (c-i) and spectral profile (c-ii) of chaotic state with only one pump. (c-iii) Schematic diagram of chaotic state with only one pump. Calculated temporal profile (d-i) and spectral profile (d-ii) of two solitons state with heat balance scheme. (d-iii) Schematic diagram of two solitons state with heat balance scheme.

Fig. 2. Experimental setup and single perfect soliton. (a) Physical drawing of a microresonator. (b) Scanning electron microscope image of the microresonator. (c) Experimental setup for perfect soliton generation. ECDL, external cavity diode laser; EDFA, erbium-doped fiber amplifier; FPC, fiber polarization controller; Cir, circulator; TEC, thermoelectric controller; OSA, optical spectrum analyzer. The zoom in of the chip shows a scanning-electron micrograph of the waveguide cross-section. (d) Low-noise single soliton state (blue curve) with a sech² fitting spectral profile (red dashed curve). (e) Microwave beat note of the photo-detected soliton.

Fig. 3. (a–c) Experimentally measured spectra for 1-, 2- and 4-solion states, respectively. (d–f) Calculated different soliton states. Insets shows the corresponding temporal profile where oscillation is avoided.

Fig. 4. (a–d) Experimentally measured spectra of different two solions states.

Fig. 5. (a–d) Calculated spectra of different two-solion states. Insets show corresponding temporal profile.