The Flat Lens Violated The Laws Of Optics And Compressed Light To Nanoscales
Physicists have created a metamaterial lens that can compress light rays into structures several nanometers wide that "violate" the classical laws of optics, according to the results published in the scientific journal Optics Letters.
Nanoparticles made of dielectrics and thin strips made of certain metals, such as gold or silver, can absorb visible light, transmit it further, and re-emit it as other forms of electromagnetic waves. That is possible due to the so-called surface plasmons-collective vibrations of electrons that can absorb and emit energy in the form of light waves.
Over the past ten years, scientists have discovered dozens of examples that such structures actually exist, for example, in many paints and masterpieces of art created during the ancient and middle ages. In addition, physicists have figured out how to apply knowledge about these structures in practice. For example, six years ago, scientists at the Massachusetts Institute of Technology created a transparent color display based on plasmons, and their colleagues adapted these structures to create devices that can hide objects from the microwave or infrared radars.
Scientists from Russia and Denmark have adapted plasmons to solve one of the most important problems that prevent the use of light as a carrier of information inside the microprocessors of computers and other computing devices.
The fact is that because of light diffraction – a phenomenon in which light waves bend around obstacles less than half the length of the light wave, the light analogs of transistors can not be less than 200 nanometers for visible light and about 500 nanometers for infrared radiation.
Five years ago, scientists at MIPT showed that this can be achieved by compressing light using sources of plasmon vibrations and so-called polaritons-quasiparticles that simultaneously behave as both a wave and a particle. Now physicists from Russia and Denmark have solved this problem in practice, creating a kind of lens that can "compress" the light beam to nanoscale using plasmons and polaritons.
This device, the so-called "metalens," is a square block of material that does not conduct electric current, measuring 5 by 5 microns and 250 nm thick. It is attached to a film of gold, on the back surface of which a diffraction grating is also applied. Scientists have chosen their sizes in such a way that they compress the light beam falling on them to 60% of its wavelength.
Such a structure, as scientists explain, allows a lens made of metamaterials not only to compress light but also to focus it and manipulate its movement due to the formation of a so-called plasmon nanostructure, the existence of which Russian researchers were able to confirm experimentally for the first time.
The creation of metalens, according to the authors of the article, opens the way for the development of full-fledged photonic chips and the appearance of the first light computers in the near future. This, in particular, can be helped by the fact that such nanostructures can be "printed" using existing lithographic technologies that have been used in the microprocessor industry for many decades.