An international team, which includes scientists from the Physics Center of the University of Minho (UMinho), confined and guided the light for the first time in a space only one atom thick, creating for this a kind of atomic-scale lego with 2D materials. The innovation opens doors to new applications in lasers, sensors and detectors at the nanoscale.
The study was published in the renowned journal “Science” and, in addition to Nuno Peres and Eduardo Dias, joined the Barcelona Institute of Photonic Sciences (ICFO), the Massachusetts Institute of Technology (MIT) and the support of Graphene Flagship, a consortium with the biggest European funding ever.
This is what is called “putting Rossio into the alleyway”. To understand the impact of this maximum confinement of light, just remember that all electronic devices, from computers to smartphones, have millions of transistors. The first transistor measured a centimeter 70 years ago; with evolution, it is now a thousand times smaller than a hair. Scientists try to reduce as much as possible the size of the devices that control and guide light, as this can be an ultra-fast communication channel, for example, between sections of a chip and in ultra-sensitive sensors.
The present challenge for science is to develop techniques to confine light in spaces millions of times smaller than today.
It is known that metals can compress light on the wavelength scale, but with considerable losses of energy. The team that includes the UMinho physicists – and which was coordinated by Frank Koppens, from ICFO – has now changed the paradigm. He built a nano-optical lego formed by a monolayer of graphene (a type of carbon), a monolayer of hexagonal boron nitride (insulator) and, on top, a series of metal rods, as if they were Roman columns. Graphene was used because it is able to “guide” oscillations of electrons that interact strongly with light.
Infrared light was then sent through that device, reducing the space between the graphene and the metal to the maximum limit. Surprisingly, light continued to propagate freely and efficiently in the space occupied by a single atom, without energy losses, and applying a simple electrical voltage could activate or deactivate this propagation.
The discovery could potentially allow applications in new types of lasers, sensors, detectors and ultra-small optical switches. More: it allows exploring the manipulation of infrared light at the atomic scale and also extreme interactions between light and matter that were not possible before.
Eduardo Dias, 24 years old from Braga, has a degree and a master's degree in Physics from UMinho and the study now published began with his master's thesis. He is responsible for all the theoretical calculations of this investigation, under the scientific supervision of Nuno Peres. He is doing his PhD at ICFO.
Nuno Perez was born 50 years ago in Arganil, Coimbra. Since 2004, the professor and vice president of the School of Sciences at UMinho has been studying the electronic and optical properties of two-dimensional materials such as graphene. It won, among others, the “Gulbenkian Science”, “Merrito à Pesquisa da UMinho” and “Seeds of Science” awards.
It is the Portuguese whose scientific publications are the most cited internationally, according to Clarivate Analytics.
Author: Communication, Information and Image Office – University of Minho
Science in the regional press – Ciência Viva
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