A single-shot pump-probe technique for measuring ultrafast absorption dynamics in a single-beam basis

We demonstrate a single-shot pump-probe technique in a single-beam basis. A transmissive annular echelon is used to spatially encode a single pulse, and generates a pump pulse and a probe pulse train with approximately 8 ps delay time and 40 fs time interval. Using this technique, we studied the ultrafast absorption dynamics of ZnSe at a wavelength of 515 nm. And our results indicate the ZnSe has an ultrafast two-photon absorption process and a slow carrier absorption process at 515 nm. In addition, with the help of a neutral density filter (ND), we also investigated the effect of probe intensity on the experimental results.