Recently, our university's International Joint Research Center for Nanophotonics and Metamaterials (referred to as the "MetaNano Center"), in collaboration with teams from Aalto University in Finland, University of Eastern Finland, and Karlsruhe Institute of Technology in Germany, has made significant progress in the field of photonic time crystals. Theoretically, it has been proven that by periodically modulating materials with resonant properties, an infinitely wide momentum bandgap can be achieved, which allows for an exponential amplification of all photonic modes in the momentum spectrum, solving the long-standing theoretical challenge of the momentum bandgap limitation in photonic time crystals. The research findings were published on November 12th in the international top-tier journal Nature Photonics under the title "Expanding momentum bandgaps in photonic time crystals through resonances." This important discovery is expected to break the dependence of photonic time crystals on high-power modulation.

Schematic diagram of photonic time crystals based on 

silicon nanosphere array metasurfaces

Photonic time crystals are a special type of optical structure that varies periodically with time and can amplify light energy like a laser. This structure can create a "momentum bandgap" that allows light energy within the bandgap to be exponentially amplified over time. Some scholars previously believed that creating such a bandgap would require a significant amount of energy, potentially damaging the material. This work confirms that if the material can generate electromagnetic resonance on its own, then only a small amount of energy is needed to create this bandgap. This provides a new approach for manufacturing more efficient lasers, directional light sources, and advanced sensors.

Professor Xuchen Wang from our university is the first author and corresponding author of the paper, and Dr. Puneet Garg from Karlsruhe Institute of Technology in Germany is the co-first author and corresponding author. Harbin Engineering University is the first institution and the first corresponding institution. This work was supported by the central university business fund.

The MetaNano Center has built an international joint innovation team around the field of multi-physics metamaterials theory and device applications, exploring new paradigms for cooperation with overseas universities in the new era, and coordinating the advancement of international education, science, and technology, and talent work. It synergistically empowers new quality productivity and conducts basic and applied basic research in the fields of multi-physics field energy enrichment and transmission, nanophotonic energy devices, and other areas, achieving a series of innovative results. As the first institution or corresponding institution, Harbin Engineering University has published over 50 papers in top international journals such as Nature Electronics, Nature Photonics, Nature Materials, Nature Nanotechnology, Nature Communications, and Physical Review Letters.

"Nature Photonics" is a sub-journal of Nature, an academic publication by Springer Nature, and is the top-ranked journal in the field of optics, enjoying a very high reputation in the international optics community with an impact factor of 39.728.

Source link：https://www.nature.com/articles/s41566-024-01563-3