Researchers Create World’s First All-Optical Photonic Time Crystal

International Team Produces World’s First All-Optical Photonic Time Crystal

The successful creation of the photonic time crystal relies heavily on HZDR’s powerful TELBE superradiant terahertz source. According to Jan-Christoph Deinert, the coordinator of the TELBE facility, TELBE’s unique ability to generate high-field, phase-stable terahertz pulses was critical to the experiment. This system enabled scientists to explore a previously inaccessible form of light-matter interaction within the terahertz range.

Exploring the Terahertz Frequency Frontier

At École Polytechnique, assistant professor Yannis Laplace and his team at the Laboratory of Irradiated Solids (LSI) focus on developing photonic devices capable of controlling light in the terahertz frequency spectrum. This specific part of the electromagnetic spectrum is largely underused and sits positioned between conventional electronics and photonics.

Research in this domain is advancing rapidly because terahertz frequencies operate 1,000 times faster than those used for standard electronic components, potentially offering powerful new methods for examining and manipulating matter.

The THz range represents the frontier between electronic and photonic technologies, Laplace explains. 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.

Modulating Light Across Time Rather Than Space

Conventional photonic crystals are nanostructured materials featuring a repeating optical pattern, such as a lattice, that dictates how photons move through them. By carefully arranging materials with differing shapes and refractive indexes, scientists can block, guide, or strengthen selected wavelengths of light, controlling photons in a manner similar to how semiconductors control electrons.

While earlier experiments by the team demonstrated that external factors like temperature and magnetic fields could alter the ability of photonic crystals to capture light, the resulting optical behavior remained fixed over time once those conditions were established.

The newly developed device introduces a repeating pattern in time rather than relying solely on spatial arrangements. Its optical properties, including reflectivity and resonance frequency, can be altered dynamically on picosecond timescales, which is close to the timescale of light’s own oscillations.

By extending photonic crystals from space to time, we open a new dimension for light control — and a novel path toward amplification and lasing, researchers noted.

Plasmonic Metamaterial Construction

To construct this novel device, the researchers collaborated with Thales’ Laboratoire Albert Fert and Polytechnique’s Physics of Interfaces (PICM) laboratory to build a specific form of photonic crystal known as a plasmonic metamaterial.

The constructed material incorporates micrometer-scale gold crenelated structures positioned directly above an insulating layer alongside a semiconductor composed of a mixture of indium and antimony. Within this design, the gold structures form tiny cavities that effectively confine light between the gold and semiconductor layers.