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[en] In this paper, we show the ability of usage intercalated few-layer graphene for the development of an optically tunable absorbing metasurface. The geometrical parameters of the metasurface are optimized using the equivalent circuit model theory. Depending on the geometrical parameters, the metasurface shows frequency or absorption level tunability: the first design allows us to achieve the modulation of absorption up to 35%, while the second one shows absorption maximum frequency modulation of δν = 0.15 THz. The analytical results are proven by numerical simulations and explained by the interference theory. The suggested metasurface enables us to achieve an optically controllable absorption for a wide range of applications in terahertz imaging, selective absorption, and photo-detection. (paper)

[en] Metasurfaces and nanoantennas are redefining what can be achieved in terms of optical beam manipulation, as they provide a versatile design platform towards moulding the flow of light at will. Yet, once a conventional metasurface is designed and realised, its effect on optical beams is repeatable and stationary, thus its performance is ‘locked-in’ at the fabrication stage. A much wider range of applications, such as dynamic beam steering, reconfigurable and dynamic lensing, optical modulation and reconfigurable spectral filtering, could be achieved if real-time tuning of metasurface optical properties were possible. Chalcogenide phase-change materials, because of their rather unique ability to undergo abrupt, repeatable and non-volatile changes in optical properties when switched between their amorphous and crystalline phases, have in recent years been combined with metasurface architectures to provide a promising platform for the achievement of dynamic tunability. In this paper, the concept of dynamically tunable phase-change metasurfaces is introduced, and recent results spanning the electromagnetic spectrum from the visible right through to the THz regime are presented and discussed. The progress, potential applications, and possible future perspectives of phase-change metasurface technology are highlighted, and requirements for the successful implementation of real-world applications are discussed. (paper)

[en] The investigation and development of new functional two-dimensional materials is one of the most important challenges for terahertz (THz) photonics and optoelectronics. These materials allow to dynamically manipulate the properties of the THz radiation. Graphene and graphene-based materials are the promising candidates for this task as they are efficient and fast-acting in the THz frequency range. In this work we have experimentally studied the properties of novel material based on few-layered graphene intercalated with ferric chloride (FeCl₃-FLG) in the THz frequency range. In particular, the influence of infrared optical pumping intensity (using 980 nm continuous-wave (CW) laser) on the spectral properties of FeCl₃-FLG was investigated. The experimental results have shown the efficiency of the suggested method of radiation characteristics control. (paper)

[en] Design and fabrication technology of a microcavity structure based on a double heterojunction in macroporous silicon is suggested. The fabrication process of a strip of a 2D photonic crystal constituted by a finite number of lattice periods and the technique for defect formation by local opening of macropores on the substrate side, followed by filling of these macropores with a nematic liquid crystal, are considered.