Fig. 1. Optical path of stable frequency laser in FY satellite

Fig. 2. Working principal of frequency stabilization

Fig. 3. Schematic of sealing of the DFB laser

Fig. 4. Test result of the frequency stability

Fig. 5. Onboard working result of stable frequency laser in FY satellite

Fig. 6. Working principle of the frequency reference laser

Fig. 7. Schematic of frequency stabilization

Fig. 8. Shape of the multi-pass cell

Fig. 9. Measurement result of frequency stability of the frequency reference laser

Fig. 10. Schematic of the CAPR laser

Fig. 11. Basic and second harmonic output power of the laser

Fig. 12. Power relations between the basic and SHG light

Fig. 13. Test result of the switch response time

Fig. 14. Schematic of the frequency stabilization^[31]

Fig. 15. Measured result of the frequency stability

Fig. 16. Schematic of the Taiji ultra stable laser

Fig. 17. Schematic of the NPRO laser

Fig. 18. Test results of frequency stability and frequency noise of the Taiji-1 laser

Fig. 19. Schematic of frequency stabilization technology based on ultra stable fiber

Fig. 20. Experimental results of the ultra stable laser