Fig. 4: A supercontinuum enables quantitative absorption spectroscopy in single-shot measurements.

A A schematic of the experimental setup and purge box used for gas absorption measurements. B Experimental data plots with fits for delay line, chirped pulse, and supercontinuum signals, showing unreliable fits for supercontinuum and chirped pulses due to a short measurement window of 2 ps. C Expanding the measurement window (i.e., the chirped pulse width, T_c) improves the accuracy of the fits for extracting the line-averaged number density in single-shot measurements (i.e., concentration) of gaseous molecules (\(\widetilde{{\mbox{n}}}=\frac{1}{{\mbox{L}}}{\int }_{0}^{{\mbox{L}}} {\mbox{ndL}}\), where n is the number density and L is the path length). However, (D) the uncertainty in estimating \(\widetilde{{\mbox{n}}}\) increases as T₀ increases (i.e., as the probe bandwidth decreases). The uncertainty (\({\delta}\widetilde{{\mbox{n}}}\)) was quantified by calculating the standard deviation of the \(\widetilde{{\mbox{n}}}\) vs measurement window curve for a given T₀, after subtracting its moving average to remove the baseline variation. E Accurate fits of H₂O rotational lines are achieved in the limit of long T_c and short T₀ for single-shot schemes. A bootstrap statistical analysis³⁶ gave the confidence intervals of these fits.