chapter
2 Pages

Conclusion

ByVictor V. Kotlyar, Sergey S. Stafeev, Anton G. Nalimov

As a conclusion, we present a brief review of modern works on optical components with a metasurface. In recent years, flat optical components of microoptics with a thickness less than the wavelength, consisting of a set of subwavelength elements (columns, slots, segments, gratings) of metal or semiconductor, which can simultaneously change the polarization, amplitude, and phase of the incident laser radiation, are studied in optics. Such photonic components are called components with a metasurface (CMPs). An overview of them can be found in References [320, 321, 403]. Below are references that will allow the reader to evaluate the progress and direction of current research in the field of metasurfaces. In particular, in a number of works [404–410], metasurfaces based on graphene are considered. In References [404, 405], metasurfaces that allow control of the phase and amplitude of the light reflected from it are implemented to control infrared radiation. Moreover, it was shown in Reference [405] that the interaction of light with a thin layer of graphene can be amplified using a subwavelength optical resonator. In Reference [407], a hyperbolic metasurface based on graphene strips for terahertz radiation and near infrared (IR) range was implemented. In Reference [408], plasmon excitation in an array of graphene microlens was studied. Plasmon excitation in a graphene taper was observed in Reference [411] by scanning near-field optical microscopy. In Reference [412], the propagation of plasmons in a graphene layer, over which an atomic force microscope (AFM) probe is located, is investigated by light with a wavelength of 11.2 μm. Filters based on graphene and dielectric layers were considered in Reference [413]. There are interesting studies of metasurfaces reacting differently to different polarizations of the light incident on them. For example, in References [414, 415], the metasurface is used to excite surface plasmons that propagate in different directions, depending on the direction of the circular polarization of the light exciting them. And in Reference [416], again, depending on the direction of rotation of the circular polarization, the layer of the metasurface acts as a collecting or diverging lens. The gradient metasurface considered in Reference [417] is capable of transforming propagating waves into surface waves with an efficiency close to 100%. And in Reference [418] the gradient metasurface is used as a lens operating in the wavelength range from 750 nm to 950 nm. In Reference [419], a one-dimensional metal lattice (the simplest metasurface) is used to control surface plasmons. It is shown numerically that the same grating with a period of 120 nm, a step width of 60 nm and a height of 80 nm, illuminated by light from different wavelengths, forms plasmons that propagate in different ways: one can observe the phenomenon of negative refraction, ordinary diffraction, and non-diverging waves. Metasurfaces based on V-shaped antennae are described in References [420, 421] In Reference [420], a two-layer metasurface operating on transmission in the visible wavelength range was considered. The metasurface under investigation consisted of a layer of V-shaped antennae of gold and a gold film with V-shaped holes that complemented the antennae in accordance with Babinet’s principle. The characteristic antenna size was 150 280nm, and the two gold layers were separated with a layer of 100-nm thick hydrogen-silsesquioxane. An ultrathin hologram (30 nm) based on the use of a metasurface is considered in Reference [422]. Holograms based on the metasurface, considered in Reference [423], created an image of 330 × 232 μm in size. A separate hologram pixel was a metal nano-column oriented in space. The spin Hall effect for photons, observed in the layer of the metasurface, was considered in Reference [424]. A metasurface that changes its optical properties under the influence of an electrical voltage applied to it is described in Reference [425] – depending on the voltage, it is possible to change the absorption in the layer of the metasurface by 30%. Metasurfaces are a special case of metamaterials. The evolution from metamaterial to metasurface and further to individual meta-devices is described in Reference [426].