Warsaw [Poland], April 14 (HBTV): Researchers have developed a nanoscale structure capable of trapping infrared light in a layer just 40 nanometres thick—over 1,000 times thinner than a human hair—marking a significant step forward in photonics research.
The work, carried out by scientists from the Faculty of Physics at the University of Warsaw in collaboration with the Lodz University of Technology, Warsaw University of Technology, and the Polish Academy of Sciences, was published in the journal ACS Nano.
The structure is based on a subwavelength grating made using molybdenum diselenide (MoSe2), a specialised material with a high refractive index that allows light to slow down significantly and become tightly confined within extremely thin layers.
Researchers said the approach enables infrared light to be concentrated far beyond previous limits, allowing it to be intensified and manipulated at the nanoscale.
Light, which behaves both as a particle and a wave, has a wavelength that traditionally limits how small a structure can be while still controlling it effectively. Infrared light in particular has long wavelengths, making confinement in ultra-thin structures technically challenging.
The team demonstrated that by engineering a subwavelength grating—made of closely spaced parallel strips acting like a prism-like system—they could trap infrared light in a layer only 40 nanometres thick while also reflecting and confining it efficiently.
Earlier versions of similar structures made from materials like silicon or gallium compounds required much thicker layers and lost effectiveness when scaled down. Researchers said MoSe2 overcomes this limitation due to its unusually strong optical properties.
Beyond trapping light, the material also enables nonlinear optical effects such as third harmonic generation, where infrared light is converted into visible blue light. The study found this effect was more than 1,500 times stronger compared to flat layers of the same material.
The team also used molecular beam epitaxy (MBE) to grow large, uniform MoSe2 films spanning several square inches, addressing limitations of earlier methods that could only produce very small samples.
Researchers said the advance could help pave the way for smaller and faster photonic technologies, including future photonic integrated circuits, where light replaces electrons to transmit information more efficiently.
(ANI)