Researchers propose a novel methodology for the characterization of light-matter interaction at atomic size

The light in the tunnel
Credit: IMDEA Nanociencia

Photonic cavities are an essential part of many modern optical devices, from laser pointers to microwave ovens. Just as we can store water in a tank and create standing waves on the surface of the water, we can confine light in a photonic resonator whose walls are strongly reflective. Just as water surface waves depend on the geometry of the tank (shape, depth), specific optical modes can be created in a photonic cavity whose properties (colour and spatial distribution of intensity) can be tuned by changing the dimensions of the cavity. When the size of the cavity is very small—much smaller than the wavelength of the light confining it (nano-cavity in the case of visible light)—an intensification effect of the light is produced that is so strong that it influences the electrons on the walls of the cavity. A mixture between photons and electrons is then produced, giving rise to hybrid modes between light and matter known as plasmons.

Plasmons in optical nano-cavities are extremely important for many applications such as that allow the detection of individual molecules, or the manufacture of nanolasers that could operate with hardly any electrical current consumption. However, the characterisation of these plasmonic modes is generally very complex, because of the tiny size of the cavities that makes extremely difficult to access them by external signals.




Researchers from Universidad Autónoma de Madrid, IMDEA Nanociencia and IFIMAC have developed a method to overcome this problem by simultaneously determining the energy distribution of the tunnelling electrons and the light emitted in a scanning microscope. They have exploited the tunnelling effect to create optical resonators of atomic dimensions and to study their optical properties, unravelling for the first time the contributions due to the of the tunnelling particles from the effects originated by the plasmonic modes in the cavity.

This work proposes a novel methodology for the characterization of -matter interaction at atomic size, and may have important technological implications for the development of chemical sensors of single molecules, new sources of single or interlaced photons or nanolasers that are active at extremely low pumping powers.

The research has been published in the prestigious journal Nature Communications.

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More information: Alberto Martín-Jiménez et al. Unveiling the radiative local density of optical states of a plasmonic nanocavity by STM, Nature Communications (2020). DOI: 10.1038/s41467-020-14827-7
Journal information: Nature Communications

Provided by IMDEA Nanociencia
Citation: Researchers propose a novel methodology for the characterization of light-matter interaction at atomic size (2020, March 25) retrieved 31 March 2020 from https://phys.org/news/2020-03-methodology-characterization-light-matter-interaction-atomic.html

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