Fig. 3: Fourier-transformed DCOS.

a A Fourier-transformed PA spectrum with resolved comb lines. The acquisition time is 2 s. The side lobes of the resolved lines in the right inset are due to the apodized Fourier transformation. As such, these artifacts do not influence the measurements of molecular lines. Also, the spikes around 68–69 kHz are caused by the high-intensity lines at the center of the EO combs (Supplementary Fig. 1). b PA spectra obtained in a single shot measurement of 50 ms (blue) and with 20-fold averaging (orange) in 1 s. c Comparison between the experimental data (orange dots) and the HITRAN model (black line). d Broadband molecular spectra with a spectral range of > 2.1 THz. The point spacing for the experimental data (purple) is 400 MHz (or ~3 pm). The black line shows the HITRAN model for comparison. All the spectra in Fig. 3 are recorded with 10% ¹²C₂H₂ at atmospheric pressure.