Scientists developed a nanolaser: Silver nanocubes enable light generation
December 13, 2024

Scientists developed a nanolaser: Silver nanocubes enable light generation

Researchers at Lithuania’s Kaunas University of Technology (KTU) and Japanese scientists have developed a unique nanolaser. Although the size of this laser is so small that its structure can only be seen through a high-powered microscope, its potential is huge. With applications in early medical diagnosis, data communications and security technology, this invention may also become a key tool in studying the interaction of light and matter.

Depending on the application, the way a laser amplifies and produces light varies, which determines the color of the radiation and the quality of the laser beam.

“Nanolasers are lasers that use structures a million times smaller than a millimeter to generate and amplify light, and the laser radiation is produced in an extremely small volume of material,” said Mindaugas, one of the authors of the invention. Dr. Juodėnas said.

Lasers work like a hall of mirrors

This type of nanolaser has been under research and development for some time. However, the KTU scientists’ version is unique in its manufacturing process. It uses silver nanocubes, neatly arranged on a surface and filled with optically active materials. This creates the mechanism needed to amplify light and produce the laser effect.

“Silver nanocubes are very small single-crystal silver particles with excellent optical properties. They are an important component of the nanolaser we developed,” says Juodėnas, a researcher at KTU’s Institute of Materials Science.

Nanocubes are synthesized using a unique process invented by Japan’s KTU partners to ensure their precise shape and quality. These nanocubes are then arranged into two-dimensional structures using a nanoparticle self-assembly process. During this process, particles naturally arrange from the liquid medium into the pre-patterned template.

When the template parameters match the optical properties of the nanocubes, a unique phenomenon called surface lattice resonance occurs, allowing for efficient light generation in optically active media.

While conventional lasers use mirrors to create this phenomenon, the nanolaser invented by KTU researchers uses a surface with nanoparticles. “When silver nanocubes are arranged in a periodic pattern, light is trapped between them. In a way, this process is reminiscent of an amusement park hall of mirrors, but in our case, the mirrors are nanoscale The meter cube and the visitors to the park are the light,” explains Juodėnas.

This “trapped” light accumulates until it eventually exceeds the energy threshold of stimulated emission, producing an intense beam of light with a specific color and direction. Juodėnas reminds us that the word laser is Light amplification by stimulated emission of radiationthat is, the above process.

International funding helped develop the idea

By using high-quality, easy-to-produce nanomaterials such as silver nanocubes, the energy required to operate the laser reaches record low levels, allowing mass production of the laser.

“Chemically synthesized silver nanocubes can be produced in hundreds of milliliters, and their high quality allows us to use nanoparticle self-assembly technology. Even if their arrangement is not perfect, their properties make up for this,” says Juodėnas .

However, the simplicity of the method, which should have sparked interest in the initial stages, turned off Lithuanian research funding agencies. “Sceptics questioned whether the simple method we used could create sufficiently high-quality structures for nanolasers,” recalls Professor Sigitas Tamulevičius.

The KTU Institute of Materials Science team was so convinced of the quality of the nanolaser they were developing that they received funding from an international organization, which, as Juodėnas says, evaluated the idea’s prospects: “After a lot of work and a lot of experiments, We have shown that even imperfect arrays can be effective if high-quality nanoparticles are used.

Another invention by KTU researchers also uses neat arrangements of nanoparticles to create anti-counterfeiting marks, a technology that has gained international recognition and has been approved by the US and Japanese patent offices.

In the future, the nanolasers created by KTU researchers could be used as light sources for ultra-sensitive biosensors for early detection of diseases or instant monitoring of biological processes. It could also have applications in microphotonic chips, identification technology and authentication devices, where the unique structure of the beam is crucial. Additionally, it could support fundamental research into how light interacts with matter at the nanometer scale.

2024-12-10 16:49:46

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