Fig. 1. Structure diagram of TDLAS measurement system

Fig. 2. O₂ absorption line based on the HITRAN2020 database

Fig. 3. Relationship between laser output power and the injected current

Fig. 4. S-G filtering results for different orders

Fig. 5. S-G filtering results for different window lengths

Fig. 6. The baseline of the reference light fitted by a polynomial

Fig. 7. Absorption spectra of oxygen in air at 291 K

Fig. 8. The variation of the TDLAS signal amplitude with modulation depth

Fig. 9. 2f signal and noise for the TDLAS system