Researchers from Imperial College London and University of Exeter published a technical paper titled “Ultrafast switching of optical properties in a doped semiconductor by intense femtosecond laser pulses.” Abstract“The rapid switching of materials when excited by ultrashort pulses of light is central for many optical technologies, and in particular to the developing field of time-varying metamaterials. Here we combine experiments and theory to unravel different regimes of interactions and a response saturation for a 44 fs, near-infrared pump pulse exciting a switchable doped semiconductor indium tin oxide thin film target. Our calculations show that saturation at high pump intensities arises because the pump heavily depopulates electrons from below the Fermi level. “Ultrafast Switching of Optical Properties in a Doped Semiconductor by Intense Femtosecond Laser Pulses.”