Fig. 1. Diagram of optical frequency comb frequency domain

Fig. 2. Diagram of optical frequency comb time domain

Fig. 3. Dual-comb system repetition rate difference asynchronous locking device

Fig. 4. PZT tuning the repetition rate range

Fig. 5. Diagram of normalized dual-comb output spectra

Fig. 6. Variation of repetition rate difference and Allan deviation during free-running. (a) Variation of repetition rate difference; (b) Allan deviaition

Fig. 7. Dual-comb repetition rate difference independent locking scheme with common Rb clock reference

Fig. 8. Variation of repetition rate difference and Allan deviation after independent locking. (a) Variation of repetition rate difference; (b) Allan deviation

Fig. 9. Variation of repetition rate difference and Allan deviation after asynchronous locking. (a) Variation of repetition rate difference; (b) Allan deviation

Fig. 10. Comparison of Allan deviation of repetition rate of LO laser locked by two methods