Fig. 1. Schematic diagram of mid-infrared dual-comb system

Fig. 2. The output characteristics of the dual wavelength pulses

Fig. 3. Long term stability of repetition rates of dual wavelength pulses

Fig. 4. Output spectra of the beat signal

Fig. 5. The optical spectra of the dual-wavelength pulses after amplification and PPLN

Fig. 6. The RF spectrum of the mid-infrared beat signal