Fig. 1. Schematic diagram of multiheterodyne detection in frequency domain of EODCS

Fig. 2. Diagram of EODCS experimental setup

Fig. 3. Time and frequency domain characteristics of dual-comb system. (a) Heterodyne interferograms in the time domain; (b) Fourier-transformed radio frequency spectrum

Fig. 4. Signal-to-noise ratio as a function of acquisition duration

Fig. 5. Comparision between normalized dual-comb spectra and the HITRAN simulation data of different gases. (a) CO₂ during 6361.91~6365.35 cm^-1; (b) CO at 6338.59 cm^-1

Fig. 6. Concentration measurement of CO₂ different absorption peaks

Fig. 7. Evolution of CO concentration