Tracking ultrafast changes of optical properties in XUV-ray pumped diamond

Electronic excitation in semiconductors, irradiated with intense femtosecond X-ray pulses, changes their optical properties—such as reflection, absorption, transmission, and polarization. Given that these changes occur on femtosecond timescales, they can be harnessed to design ultrafast optical switches. In this study, we computationally investigate the effects of ultrafast extreme UV-ray radiation (XUV) on diamond, specifically examining changes in optical reflection, transmission, and polarization. The predictions were obtained from our XTANT code designed to track transient changes in the material's optical properties by accounting for alterations in both its electronic and atomic structure. We discuss possible mechanisms for the observed polarization angle rotation, as well as the variations in reflectivity and transmissivity.