Fig. 1. Seeder frequency stabilization，frequency shifting system experimental device diagram

Fig. 2. Absorption spectra of CO₂ and H₂O at 1.5 μm

Fig. 3. Laser frequency stabilizer section

Fig. 4. CO₂ absorption spectra measured at atmospheric pressure

Fig. 5. CO₂ absorption spectrum at 1 572.334 0 nm under different pressures

Fig. 6. Laser frequency shifter section

Fig. 7. Absorption peak and trough positions at 1 572.334 0 nm

Fig. 8. Comparison of low pressure sweep spectrum data with HITRAN database data

Fig. 9. Wavelength variation of lasers without frequency stabilisation algorithms

Fig. 10. Photodetector 1 and 2 voltage value and OD value variation curve

Fig. 11. Laser peak-seeking and frequency-stabilised wavelength variation plot

Fig. 12. Wavelength meter to monitor laser wavelength shift process