Researchers at the Institute of Photonic Sciences (ICFO), in collaboration with an international team including MIT, Duke University, Université Paris-Saclay, and Universidad do Minho have created the smallest optical cavity ever built for infrared light. Their findings could lead to a new generation of optical circuitry, leading to breakthroughs in medicine, biotechnology, and even food inspection.
The breakthrough was made possible using so-called “plasmons” – oscillations of electrons that strongly interact with light. They’ve allowed researchers to confine light to tiny spaces, but only in a single direction. Plasmons’ ability to interact with microscopic particles like atoms depends on how small a volume they can be confined to. Confining plasmons at the microscopic level in this way is referred to as an optical cavity, according to SciTech Daily.
Itai Epstein, first author of the study, told SciTech Daily, “the main obstacle that we encountered in this experiment resided in the fact that the wavelength of light in the infrared range is very large and the cubes are very small, about 200 times smaller, so it is extremely difficult to make them interact with each other.”
To achieve their results, the team used 50-nanometer nanocubes randomly sprinkled on top of the graphene sheet. When they sent infrared light through the device, each nanocube combined with the graphene was able to act as a single optical cavity.