Recently, the International Joint Research Center of Nano-optics and Metamaterials of our university (hereinafter referred to as the "Ultra-nano Center") has achieved important progress in the field of photonic time crystals in cooperation with teams from Aalto University in Finland, the University of Eastern Finland and the Karlsruhe Institute of Technology in Germany. It has been theoretically confirmed that by periodically modulating materials with resonant characteristics, an infinitely wide momentum bandgap can be achieved, which can exponentially amplify all optical wave modes in the momentum spectrum and solve the long-standing theoretical problem of the limited momentum bandgap in photonic time crystals. The research results were published on November 12 in the international top journal "Nature Photonics" under the title "Expanding momentum bandgaps in photonic time crystals through resonances". This important discovery is expected to get rid of 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 kind of optical structure that changes periodically over time and can amplify light energy just like a laser. This kind of structure can create a "momentum bandgap", allowing the light energy within the bandgap to be exponentially amplified over time. Some scholars once believed that a large amount of energy was required to create such a bandgap, which might damage the materials. This work has confirmed that if the materials can generate electromagnetic resonances on their own, then only a small amount of energy is needed to create this kind of bandgap. This provides a brand-new idea for manufacturing more efficient lasers, directional light sources and advanced sensors.
Professor Wang Xuchen from our university is the first author and corresponding author of the paper, and Dr. Puneet Garg from the Karlsruhe Institute of Technology in Germany is the co-first author and corresponding author. Harbin Engineering University is the first unit and the first corresponding unit. This work was supported by the operating expenses of central universities.
The Ultra-nano Center has built an international joint innovation team around the fields of multi-physical field metamaterial theories and device applications, explored new cooperation paradigms with overseas universities in the new era, coordinated and promoted the work on international education, science and technology talents, jointly empowered new quality productive forces, carried out basic and applied basic research in fields such as multi-physical field energy enrichment and transmission, nano-optoelectronic energy devices, and achieved a series of innovative results. With Harbin Engineering University as the first unit or corresponding unit, more than 50 papers have been published in international top 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". It is an academic publication published by the Springer Nature Group. It is the top-ranked journal in the field of optics and enjoys an extremely high reputation in the international optical field, with an impact factor of 39.728.
Paper link: https://www.nature.com/articles/s41566-024-01563-3
