Reducing energy loss in metal nanostructures by altering geometrical dimensions

Researchers at City University of Hong Kong (CityUHK) have made a discovery that significantly reduces energy loss in metal nanostructures. By altering the geometrical dimensions of these structures, researchers have unlocked their full potential, paving the way for the development of more powerful and efficient nanoscale optical devices.

The research team is co-led by Professor Tsai Din-ping, Chair Professor in the Department of Electrical Engineering at CityUHK, and Professor Yuri Kivshar, from Australian National University. Professor Kivshar also served as a visiting research fellow at the Hong Kong Institute for Advanced Study at CityUHK in 2023.

“This breakthrough resolves the longstanding issue of energy loss, allowing for high-performance nanoscale optical devices,” said Dr. Liang Yao, from the Department of Electrical Engineering at CityUHK, who is the first author of the research article titled “From Local to Nonlocal High-Q Plasmonic Metasurfaces,” published in the journal Physical Review Letters.

A new universal rule, the inverse square root law, has been discovered, showing how adjusting the dimensions of plasmonic nanostructures can significantly reduce energy loss. This discovery bridges the gap between localized surface plasmon resonances (LSPRs) and surface plasmon polaritons (SPPs), resulting in a two-order-of-magnitude improvement in resonance quality in metal arrays. This breakthrough opens exciting possibilities for stronger light-matter interactions at the nanoscale.

Bridging high-loss localized surface plasmon resonances (LSPR) with low-loss surface plasmon polaritons (SPP) was a formidable challenge, demanding innovative thinking and a departure from conventional approaches.

This discovery has the potential to revolutionize various fields, including sensing, imaging and solar energy. With this new technique, researchers are poised to develop even more powerful and innovative optical devices, ushering in a new era of technological advancement.