Ultrafast switching of optical properties in a doped semiconductor by intense femtosecond laser pulses
File(s)
Published version
Author(s)
Type
Journal Article
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. These out-of-equilibrium interactions are difficult to capture with traditional theoretical models. 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. We model this process as a change in plasma frequency due to the excitation of hot electrons in a non-parabolic conduction band, which increases their effective mass. Our calculations show that saturation at high pump intensities arises because the pump heavily depopulates electrons from below the Fermi level. Excellent agreement with values extracted from experimental data confirms our model. For lower pump intensities, a two-temperature model is consistent with our data, but at higher intensities, it is apparent that other processes are at work, which we attribute to Auger transitions from the valence band, which introduce complex structure into the response, due to non-equilibrium rearrangement of energy between electrons and holes.
Date Issued
2026-08-04
Date Acceptance
2026-05-13
Citation
Light: Science & Applications, 2026, 15
ISSN
2095-5545
Publisher
Nature Publishing Group
Journal / Book Title
Light: Science & Applications
Volume
15
Copyright Statement
© The Author(s) 2026. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Identifier
10.1038/s41377-026-02346-x
Publication Status
Published
Article Number
336
Date Publish Online
2026-08-04