Fig. 1. Schematic diagram of the principle of mode filtering for optical frequency comb

Fig. 2. Schematic diagram of the influence of cavity mirror reflectivity on cavity transmission，cavity linewidth，and side mode suppression

Fig. 3. Optical frequency comb mode filtering scheme obtained by numerical simulation

Fig. 4. Schematic diagram of the experimental setup

Fig. 5. Transmission signal and PDH error signal of the F-P cavity before and after filtering

Fig. 6. The RF spectrum and time-domain pulse spectrum of the optical frequency comb before and after filtering

Fig. 7. The RF spectrum of the filtered comb for Expt. Ⅰ and Ⅱ

Fig. 8. The RF spectrum of the filtered comb for Expt. Ⅱ and Ⅲ，and the FSR of the mode filter cavity was 1.75 GHz

Fig. 9. The RF spectrum of the filtered comb for Expt. Ⅳ