Researchers in Poland have developed a new photonic structure capable of trapping infrared light within a layer just 40 nanometers thick, a scale more than 1,000 times thinner than a human hair. The work demonstrates how light can be confined in structures far smaller than its wavelength, addressing a longstanding challenge in optical physics.
The research was led by scientists at the University of Warsaw in collaboration with multiple institutions, including the Polish Academy of Sciences. The team used a subwavelength grating design made from molybdenum diselenide, a material with unique optical properties that enable strong light confinement at extremely small scales, according to ScienceDaily.
Controlling light at the nanoscale is central to the development of photonics, a field that aims to use light instead of electrons for processing and transmitting information. Unlike electrons, photons travel faster and do not generate heat through resistance, making them attractive for next-generation computing and communication technologies. However, the wave nature of light imposes limits on how tightly it can typically be confined.
The research team overcame this limitation by designing a grating structure with features smaller than the wavelength of infrared light. This configuration allows the structure to behave like a highly reflective surface while simultaneously trapping light within a confined space. The result is a stable optical system capable of maintaining strong light interactions in an ultrathin layer.
A key factor in the breakthrough is the use of molybdenum diselenide. Compared with conventional materials such as silicon or glass, it has a higher refractive index, meaning it slows light more effectively. This property enables stronger interaction between light and the material, allowing the structure to function efficiently even at significantly reduced thickness.
The material also exhibits nonlinear optical behavior, enabling the conversion of infrared light into visible blue light through a process known as third harmonic generation. By concentrating light within the structure, the researchers enhanced this effect substantially, achieving efficiency levels more than 1,500 times higher than those observed in flat layers of the same material.
Another important aspect of the study is scalability. Earlier methods for producing thin layers of such materials relied on exfoliation techniques, which are limited in size and consistency. In contrast, the team used molecular beam epitaxy, a controlled fabrication process that allows for the production of large, uniform films. This approach makes it more feasible to integrate the technology into practical devices.
The findings suggest that ultrathin photonic structures could play a key role in future technologies, including compact optical chips and advanced sensing systems. By demonstrating that light can be effectively manipulated in layers far thinner than previously thought possible, the research opens new pathways for miniaturizing optical components.