Trapping Light with a New Type of Nanoresonators

Controlling matter using light is one of the most advanced approaches in physics and nanophotonics, as it offers extraordinary possibilities for the development of advanced electronics and quantum computing.

Traditionally, when material interacts with light, it does so as a bulk material. To enable interaction between atoms and photons (referred to in scientific terms as 'coupling') at the quantum level, special enclosures known as nanoscale optical resonators (nano-resonators) are utilized. These are devices that allow us to "trap" light. Optical nanoresonators are essential components in various nanotechnological applications, including spectroscopy, due to their capability to effectively confine light at the nanoscale. When light enters these 'boxes', it bounces off the walls and cannot escape.

A resonator can also be thought of as a device that vibrates at a specific frequency, much like a guitar string. When a molecule or biological particle comes into contact with the nanoresonator's surface, the frequency changes, akin to a finger moving along a guitar string. As these bounces or vibrations occur within very specific frequency bands, they can be utilized to develop a variety of useful devices for spectroscopic applications, such as biosensors and photodetectors. By measuring how much the nanoresonator’s frequency changes, it's possible to identify the substance in question.

Our recent research paper, published in npj 2D Materials and Applications (a Nature partner journal), co-authored by XPANCEO co-founder and CTO Valentyn Volkov, along with a group of remarkable scientists from various universities and research centers in Spain, demonstrates the potential to create a new class of mid-IR resonators using MoO3 crystals. These crystals not only display the extraordinary properties previously reported but also introduce a new degree of freedom: twist tuning. This is the ability to control their spectral response by simply rotating the constituent material.

MoO3 is a van der Waals material that is layered and anisotropic, allowing light to couple with the crystal lattice's fluctuations. When we place a crystal like this on a metal lattice and rotate them relative to each other, the trapped light within the crystal 'senses' it, and we can therefore control the light inside the crystal. This capability enables us to adjust the resonator's frequency for specific practical applications. For example, we can create an extremely sensitive biosensor by tuning the resonator to the frequency range of a particular molecule.

For those interested in delving into the specifics of this research project, we invite you to read the full paper in npj 2D Materials and Applications: https://doi.org/10.1038/s41699-023-00387-z

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