An international group of scientists has demonstrated for the first time the possibility of a simple implementation of the so-called negative refraction of light, when light, when passing through the boundary of the separation of media, contrary to all the laws of optics, is refracted in the other direction. This is not a miracle. The phenomenon was theoretically substantiated about 60 years ago. But metamaterials were used to implement it, which is difficult and does not work completely. Scientists have proven that everything can be much simpler.
Image source: Lancaster University
As is known, light – photons – interact with matter mainly through the electrical component, not the magnetic one. Photons of a certain wavelength are absorbed by electrons in atoms, the electrons move to a new energy level and then, already excited, emit photons, returning to their previous state, and the photons fly further in the direction prescribed to them by nature.
A team of scientists from the British University of Lancaster and the Japanese NTT Basic Research Laboratories created, atom by atom, a state of the crystalline structure in which a group of atoms, rather than each individual one as in nature, was responsible for interaction with photons. The interaction with light was actually a pure crystalline lattice – a certain material, rather than a metamaterial – a construct subject to defects and effects of radiation absorption with its conversion into heat and associated losses. Obviously, the new method is advantageous from all sides, although its implementation is not as simple as it seems at first glance.
Essentially, it is about creating atomic matrices. They are created under strict control and management, always providing the same result. In the experiment, the researchers lined up atoms in a conventional periodic crystal lattice, trapping them in a standing wave of light radiation. Scientists described it as an “egg box” made of light.
Professor Janne Ruostekoski, from Lancaster University, said: “In such cases, the atoms interact with each other via the light field, reacting collectively rather than independently. This means that the response of an individual atom is no longer a simple guide to the behaviour of the whole ensemble. Instead, collective interactions give rise to new optical properties, such as negative refraction, that cannot be predicted by studying individual atoms individually.”
The appeal of negative refraction lies in its potentially revolutionary applications, such as creating perfect lenses or superlenses capable of focusing and imaging beyond the diffraction limit, enabling sub-nanometer resolution semiconductor lithography, or developing cloaking devices that make objects invisible.