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An optical response (reflection, transmission, and absorption spectra) of a photonic crystal layer with a square lattice of chiral holes with rotation axis C2 to circularly polarized light is theoretically investigated. The geometrical parameters of the structure are selected to achieve the maximum possible circular dichroism response under the condition of complete absence of optical losses in the system. It is shown that the account of losses in thin near-surface layers of the structure, for example, due to scattering on surface roughness or absorption due to metallization of near-surface layers, leads to rapid degradation of the degree of chirality of the optical response, increasing the absorption value. Calculations are carried out for a chiral photonic crystal layer made of diamond for a wavelength range of λ=10–12 um (wave number, 830 – 1000 cm–1).

Background and Objectives: Metasurfaces are coatings consisting of elementary resonators that reemit incident UHF electromagnetic waves. By varying the parameters and arrangement of these resonators, it is possible to tune the electrical properties of the metasurface as a whole. This produces a number of practically important characteristics that are difficult to achieve with conventional attenuation coatings, and therefore prospective in the tasks of shielding of electronic devices and attenuation of the reflected signal. As there are many possible configurations of resonators, numerical experiments are needed for an effective comparative analysis. We investigate metasurfaces consisting of rectangular stripline resonators arranged on a dielectric substrate in a checkerboard pattern in two configurations. The aim of the study is to obtain scattering diagrams in numerical experiments and compare them with real structures. Materials and Methods: In this paper a computer simulation of the interaction of metasurfaces with the microwave radiation in open space is carried out using the CST Studio package with a time domain solver. Calculations were performed for several frequencies in the range of 16 to 25 GHz. Experiments were then carried out with real structures at the same frequencies, using a bistatic method of measurements. The structures, with single resonators measuring 2×4.2 mm matching the frequency range, consisted of etched copper-plated FR4 sheets overlaid on a metal plate. Results: The results show that the value of the normal component of the reflected electromagnetic wave decreases as the incident frequency approaches the resonance frequency. Also, side lobes, with a frequency-dependent magnitude, are observed. The scattering diagrams obtained with real samples show the same characteristic features with differences caused by physical particularities of the receiving antenna as well as the presence of diffraction effects. Both structures examined have shown high incident wave scattering, which is clearly indicated by the redistribution of the central lobe in diagrams. Comparison has shown that the simulated metasurfaces have similar patterns to the experimental diagrams. Conclusion: The comparative analysis has demonstrated a satisfactory fit of the simulation to the experiment. Further studies with structures of this type are planned in the future. It may be noted that the CST Studio package has worked well and will be used in future studies.