Cavity ring-down transient absorption spectroscopy (CRD-TAS): a proof of concept via detection of coherent artifacts of thin substrates

In this work, we present cavity ring-down transient absorption spectroscopy (CRD-TAS) as a novel technique to temporally resolve transient signals of two-dimensional samples with an increased sensitivity. The successful detection of coherent artifact signals in transparent materials is hereby demonstrated as an initial proof of concept of the singular CRD-TAS method. These experimental results are correlated to mathematical simulations of the nonlinear effects responsible for the coherent artifacts. With regard on the purity grade of each probed material, a weighted superposition of cross-phase modulation and two photon absorption is shown to accurately reproduce the different experimental results obtained with the CRD-TAS setup. These findings provide a good foundation for further development of the CRD-TAS technique for the investigation of the excited state dynamics of optically thin samples.