- Scientists have built the world’s first material that can rapidly change how it handles light by altering its properties over time instead of just space.
- The breakthrough works with terahertz light — a high-frequency form of radiation that sits between everyday electronics and regular light waves.
- Researchers used a special gold-and-semiconductor device powered by an ultra-intense terahertz laser source in Germany.
- The material can adjust light reflection and other behaviors in trillionths of a second, something previous devices could not do dynamically.
- Early results show it cuts energy loss of the trapped light roughly in half.
- Future versions could lead to faster optical computers, better wireless communications, improved medical imaging, and a new type of highly adjustable laser.
Conventional Crystals Versus the New Approach
Scientists have experimentally realized the world’s first all-optical photonic time crystal, a material that rapidly and repeatedly changes its optical properties over time, according to research published in the journal Nature and detailed in announcements on July 31.
The breakthrough, achieved by an international team, allows control of terahertz light at speeds far beyond conventional devices.
The work was led by researchers from École Polytechnique in France, the Collège de France, and the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in Germany. It was enabled by HZDR’s TELBE superradiant terahertz source, as reported by ScienceDaily.
Conventional photonic crystals control light through repeating spatial patterns of materials with different refractive indexes, similar to how semiconductors control electrons. Prior efforts by the team used temperature or magnetic fields to alter light-capturing properties, but those changes remained fixed once set.
The new photonic time crystal (PTC) modulates properties such as reflectivity and resonance frequency on picosecond timescales—comparable to the oscillation cycle of light itself—by introducing a repeating pattern in time rather than space.
“By extending photonic crystals from space to time, we open a new dimension for light control—and a novel path toward amplification and lasing. That could be a game-changer for optical technologies at terahertz frequencies and beyond,” said Tingwen Guo, a PhD student at École Polytechnique and lead author of the paper.
How the Device Was Built
The device is a plasmonic metamaterial consisting of micrometer-scale gold crenellated structures above an insulating layer and a semiconductor of indium antimony. These structures form cavities that trap light between the gold and semiconductor. Exciting the semiconductor surface generates surface plasmons—collective electron waves that interact with light.
Researchers directed intense, frequency-tunable terahertz laser pulses from the TELBE source at the device. This produced strong, coherent modulation of the material’s optical properties.
“TELBE’s unique ability to generate high-field, phase-stable terahertz pulses was critical,” said Jan-Christoph Deinert, coordinator of the TELBE facility. “Without this infrastructure, achieving the coherent, ultrafast modulation needed for the PTC regime would have been impossible,” as detailed in the EurekAlert release.
Experimental Results and Theoretical Confirmation
A theoretical model developed by Marco Schiró of the Collège de France and colleagues confirmed the experimental results and showed that the temporal modulation reduced photon dissipation—the portion of photons not reflected but transmitted through the material—by half.
“The theory not only reproduces the experiment but also provides the basis for guiding future discoveries in this system,” Schiró said.
Yannis Laplace, an assistant professor at École Polytechnique leading the team at the Laboratory of Irradiated Solids, noted the potential of the terahertz range: “The THz range represents the frontier between electronic and photonic technologies. It is a range full of opportunities both for science and for the society, yet is still under-developed technologically compared to its electrical and photonic counterparts. Creating photonic crystals could lead the way to the closing of this gap.”
Publication Details and Next Steps
The paper, titled “Plasmonic metamaterial time crystal,” carries the DOI 10.1038/s41586-026-10825-9 and lists authors including Tingwen Guo, Jules Sueiro, Gian Marcello Andolina, and Yannis Laplace, among others.
Researchers aim next to further reduce photon dissipation and increase the number of trapped photons. Sufficient amplification could enable new types of highly tunable terahertz lasers. Potential applications include ultrafast optical computing, advanced telecommunications, medical imaging, and on-demand control of light properties such as intensity or frequency in the terahertz band, which sits between conventional electronics and photonics and operates at frequencies about 1,000 times faster than typical electronic components.
The achievement marks the first experimental demonstration of an all-optical photonic time crystal operating in this regime.
Provided by Dallas Express
