We are reporting on laser microstructuring of thin nanocrystalline diamond membranes, for the first time. To demonstrate the possibility of microstructuring, we fabricated a diamond membrane, of 9 $\mathsf{\mu }$m thickness, with a two-dimensional periodic array of closely located chiral elements. We describe the fabrication technique and present the results of the measurements of the infrared transmission spectra of the fabricated membrane. We theoretically studied the reflection, transmission, and absorption spectra of a model structure that approximates the fabricated chiral metamembrane. We show that the metamembrane supports quasiguided modes, which appear in the optical spectra due to grating-assisted diffraction of the guided modes to the far field. Due to the C${}_4$ symmetry, the structure demonstrates circular dichroism in transmission. The developed technique can find applications in infrared photonics since diamond is transparent at wavelengths >6 $\mathsf{\mu }$m and has record values of hardness. It paves the way for creation of new-generation infrared filters for circular polarization.

Plasmons in patterned graphene have attracted much interest because of possible applications in sensing, nanophotonics, and optoelectronics. We perform mid and far-infrared optical studies of electrically doped graphene nanoribbon arrays as a function of the filling factor and compare results with the unpatterned graphene. We demonstrate that an increase in both the filling factor of nanoribbon arrays and the free carrier concentration intensifies the plasmon-plasmon and plasmon-radiation interactions. As a result, the free-carrier dynamics manifested itself in the strong plasmon redshift and increased radiative damping compared to non-interacting models for the transverse magnetic polarization. Similarly, signatures of interactions are identified for plasmons in transverse electric polarization. The obtained experimental and theoretical results provide the basis for better understanding and controlling graphene-based structures’ spectral properties, thus facilitating applications’ development.

Selectors are non-linear elements used in memristor circuits. We explore a Ti/TiO2/Ti selector as part of a one-selector–one-resistor memristor for high-density crossbar arrays. The Ti/TiO2/Ti stack is fabricated using magnetron sputtering and e-gun thermal evaporation. Selectors fabricated via magnetron sputtering consistently exhibit non-linear behavior, with a non-linearity coefficient reaching 6.2 at a low operating voltage (0.5 V), stable performance at high current, and a fabrication compatible with the standard silicon technology. The observed non-linearity can be explained by the combination of electron trapping/detrapping with an excitation energy of ∼0.3 eV. In contrast, selectors fabricated using e-gun thermal evaporation have history-dependent voltage-controlled negative differential resistance. Later, their behavior evolves into a non-linear rectifying I–V curve. This phenomenon can be attributed to the evolution of the oxygen vacancies in TiO2.

Current-voltage (I–V) characteristics of resonant-tunneling diode In_0.53Ga_0.47As/AlAs/InP structures are studied at 300 and 77 K. The peak-to-valley current ratios were determined as 22:1 and 44:1 at temperatures of 300 and 77 K, respectively, which correspond to the maximum values for InGaAs/AlAs/InP heterostructures without an additional InAs layer of a quantum subwell in their configuration.

The macro- and microstructures of LiNbO₃:Tb³⁺(2.25 wt%) and LiNbO₃:Tb³⁺(2.9 wt%) crystals were studied. It was shown that a slight increase in terbium content dramatically alters the growth domain structure and enhances fractal self-organization. The defect structure features of LiNbO₃:Tb³⁺(2.25 wt%) and LiNbO₃:Tb³⁺(2.9 wt%) single-crystal plates with an after-threshold terbium concentration were studied using optical absorption spectra, Raman scattering spectra in the frequency range of 65–4000 cm⁻¹, and IR absorption spectra in the frequency range of 1000–8000 cm⁻¹. It was shown that the LiNbO₃:Tb³⁺(2.25 wt%) plate has a lower concentration of Nb_Li point defects and a higher stoichiometry compared to the LiNbO₃:Tb³⁺(2.9 wt%) plate. A good match was found between the Raman spectra of the LiNbO₃:Tb³⁺(2.25 wt%) and LiNbO₃:Tb³⁺(2.9 wt%) plates throughout the entire studied range. A significant difference was found in the frequencies of the lines corresponding to stretching vibrations of OH⁻-groups in the vibrational spectra of the studied plates. This observation is explained by the fact that OH⁻-groups in the LiNbO₃ crystal structure are defects, and, therefore, the stretching vibrations of OH⁻-groups are not fundamental lattice vibrations. The existing selection rules for fundamental lattice vibrations, developed on the basis of group theory, do not apply to the defect sublattice.