Lithuanian And Japanese Researchers Develop Silver Nanolaser

Recently, researchers from Kaunas University of Technology (KTU) in Lithuania and the National Institute for Materials Science in Tsukuba, Ibaraki City, Japan have joined hands to successfully develop a new type of nanolaser based on silver nanocubes.
Although its structure is so tiny that it can only be observed through a high-powered microscope, the research team is confident about its potential applications.
The nanolaser has the potential for a wide range of applications in areas such as early medical diagnostics, data communications and security technologies, and it is also expected to be an important tool for the study of light-matter interactions. The way in which light is amplified and generated by the laser varies from application to application, determining the color of the radiation and the quality of the laser beam.
According to the invention's co-author, Dr. Juod?nas of KTU's Mindaugas, "Nano-lasers use structures a million times smaller than a millimeter to generate and amplify light, and their laser radiation is generated in a very small volume of material."
Although research and development of nanolasers has been ongoing for some time, the version by KTU and its Japanese partners is unique in its manufacturing process. They used silver nanocubes, which are neatly arranged on a surface and filled with optically active material, to create the mechanism needed to amplify the light and produce the laser effect.
"Silver nanocubes, as extremely small single-crystal silver particles with excellent optical properties, are the core component of our nanolaser." said researcher Juod?nas of KTU's Institute of Materials Science.
The nanocubes were synthesized through a unique process invented by KTU's partners in Japan to ensure their precise shape and quality. The cubes were then arranged into a two-dimensional structure using a nanoparticle self-assembly process. In this process, the particles are naturally aligned from a liquid medium onto a pre-designed template.
When the template parameters are matched to the optical properties of the nanocubes, a unique phenomenon known as surface lattice resonance occurs, which effectively generates light in an optically active medium.
Unlike conventional lasers that use mirrors to generate this phenomenon, the nanolaser invented by the KTU team utilizes a surface with nanoparticles. "When silver nanocubes are arranged in a periodic pattern, light is trapped by them. The process is similar to the hall of mirrors at an amusement park, but here the mirrors are the nanocubes and the 'visitors' are the light." Juod?nas visualizes the analogy.
The captured light builds up until it eventually crosses the energy threshold of the excited radiation, creating an intense beam of light with a specific color and direction. The term laser, which stands for light amplified by excited radiation, describes this process.
By using high-quality, easy-to-produce silver nanocubes, the laser is able to operate at record low energies, making large-scale production possible," notes Juod?nas. "Chemically synthesized silver nanocubes can be produced in large quantities, and their high quality allows us to use nanoparticle self-assembly techniques. Even if the arrangement is not perfect, its properties make up for it."
However, in the early stages of the project, Lithuanian research funding agencies were skeptical, despite the fact that the simplicity of the method should have attracted attention. "Some skeptics questioned whether the simple method we used could create nanolaser structures of sufficiently high quality." Prof. Sigitas Tamulevicius from the Institute of Materials Science at KTU said.
Nonetheless, the KTU team is convinced of the quality of its nanolasers and has managed to secure funding from an international organization, Juod?nas explains, "After a lot of work and experiments, we have demonstrated that if high-quality nanoparticles are used, an effective effect can be achieved, even if the arrays are not perfect."