Space-Time Crystal: A Key Piece in the Puzzle of New Optical Materials
Photonics space-time crystals are materials that could make wireless communication and laser technologies more powerful and efficient. These materials are characterized by the periodic arrangement of specific components in three spatial dimensions as well as in time, enabling precise control of light properties. Researchers from the Karlsruhe Institute of Technology (KIT) from Helmholtz Information, in collaboration with partners from Aalto University, the University of Eastern Finland, and Harbin Engineering University in China, have demonstrated how such four-dimensional materials can be utilized for practical applications. Their work has been published in the journal Nature Photonics. (Source: Karlsruhe Institute of Technology – Press Releases)
Photonics time crystals are made of materials that are spatially homogeneous but exhibit periodic changes in their properties over time. These temporal variations allow the spectral composition of light to be specifically altered and amplified, both of which are crucial factors for optical information processing. “This opens up new degrees of freedom but also presents many challenges,” says Professor Carsten Rockstuhl from KIT’s Institute for Theoretical Solid-State Physics and Institute for Nanotechnology. “This study paves the way for utilizing these materials in information-processing systems where all light frequencies can be exploited and amplified.”
A Step Closer to Four-Dimensional Photonic Crystals
The central property of a photonic time crystal is its bandgap in momentum space. To clarify, momentum is a measure of the direction in which light propagates. A bandgap indicates the directions in which light must propagate to be amplified: the wider the bandgap, the greater the amplification. “In photonic time crystals, achieving a wide bandgap requires intensifying the periodic temporal modulation of material properties, such as the refractive index. Only then can light be amplified,” explains Puneet Garg, one of the two lead authors of the study. “However, this is a significant challenge since most materials have limited capacities for such modulation.”
To address this, the research team combined photonic time crystals with an additional spatial structure, thereby constructing “photonics space-time crystals.” They integrated photonic time crystals with silicon spheres that “trap” light, holding it slightly longer than previously possible. This allows the light to interact more effectively with the periodic temporal changes in material properties. “We refer to resonances that enhance the interaction between light and matter,” says Xuchen Wang, also a lead author. “In such optimally tuned systems, the bandgap spans almost the entire momentum space, meaning that light is amplified regardless of its propagation direction. This could be the missing piece to practically utilize these novel optical materials.”
“We are very excited about this breakthrough in photonic materials and eager to see the long-term impact of our research,” says Rockstuhl. “This development unlocks the enormous potential of modern optical material research. The idea is not limited to optics and photonics but can also be applied to various physical systems, potentially inspiring new research across multiple fields.”
The research project was carried out within the Collaborative Research Center “Waves: Analysis and Numerics,” funded by the German Research Foundation (DFG), and is embedded in the Research Field Helmholtz Information of the Helmholtz Association.
KIT/A. Karbe, 12.11.2024
Note: The article has been translated from German to English. It is based on a press release from KIT.
The original press release can be found at:
Raum-Zeit-Kristall: Wichtiges Puzzleteil auf dem Weg zu neuen optischen Materialien (only in german)
The original publication can be found at (Open Access):
X. Wang, P. Garg, M. S. Mirmoosa, A. G. Lamprianidis, C. Rockstuhl and V. S. Asadchy: Expanding momentum bandgaps in photonic time crystals through resonances. Nature Photonics, 2024. DOI: 10.1038/s41566-024-01563-3
Localization in Helmholtz Information:
Helmholtz Information, Program 3: Materials Systems Engineering, Topic 2: Optics & Photonics: Materials, Devices, and Systems
Contact:
Prof. Dr. Carsten Rockstuhl
Institute of Nanotechnology & Institute of Theoretical Solid State Physics
Karlsruhe Institute of Technology
Phone: +49 721 608-46054
E-Mail: carsten.rockstuhl@kit.edu
Dr. Xuchen Wang
Institute of Nanotechnology
Karlsruhe Institute of Technology
Phone: +49 721 608-46949
E-Mail: xuchen.wang@kit.edu
Contact for this press release:
Antje Karbe
Press Officer
Karlsruhe Institute of Technology (KIT)
Phone: +49 721-608-41186
E-Mail: antje.karbe@kit.edu
About Helmholtz Information:
The Research Field “Helmholtz Information” is one of the six research fields of the Helmholtz Association and serves as its digital innovation center. Here, advanced and future computer architectures merge with insights from materials research, data science, and life sciences. Inspired by nature, supported by brain research, and enriched by modern approaches in artificial intelligence, experts from the Forschungszentrum Jülich, Karlsruhe Institute of Technology, Helmholtz-Zentrum Hereon, and the Helmholtz-Zentrum Berlin are shaping the digital future in science, business, and everyday life.
Visit our official website and follow us on our LinkedIn channel of Helmholtz Information to receive up-to-date information, event announcements, and insights into our research activities in Helmholtz Information.
