Methods for the preparation of DAST (4-N, N – dimethylamino–4'-N'-methyl stilbazolium tosylate) thin monocrystals with a thickness of a few micrometers, intended for electro-optics modulation were investigated. Thin-film single crystals are obtained, the shape and absorption spectrum of which confirms their crystalline structure of the “red” form DAST. Uniform color in the polarization contrast mode shows their monocrystallinity and uniform orientation. The materials are intended for intracavity modulation of laser radiation.

Methods of preparation of single-crystal 4-N,N-dimethylamino-4′-N′-methyl stilbazolium tosylate (DAST) films with a thickness of several micrometers, designed for electro-optic modulation, have been analyzed. Thin-film single crystals have been obtained, the shape and absorption spectrum of which confirm their crystal structure of the “red” DAST crystal form. Homogeneous luminescence in the polarization-contrast regime indicates their single crystallinity and uniform orientation. These materials are designed for intracavity modulation of laser radiation.

Layers of carbon nanotubes (CNT) with different geometric parameters were applied on narrow bandpass terahertz filter based on cross cavities. Narrow terahertz filter optical parameters were changing during infrared optical pumping of applied CNT layer.

Terahertz wire-grid polarizers are notable for broad bandwidth, high polarization extinction ratio and low transmission loss. This research is dedicated to investigation of anisotropic properties of these polarizers and shows that refractive index can be simply changed by rotating polarization angle of the incident radiation.

Subject of Research. The paper presents the study of optically tunable terahertz filter based on cross resonators coated with a layer of carbon nanotubes (CNT). We show experimentally control capability of the optical spectral characteristics of terahertz devices coated with a layer of single-wall carbon nanotubes. Method. The empirical formulas were used for calculation of the geometrical parameters of a cross-shaped resonator for a given resonant frequency and filter Q-factor. Experimental samples of the notch filter were made by laser engraving. A layer of carbon nanotubes, which were synthesized by aerosol chemical deposition, was deposited on an experimental filter sample. Experimental transmission spectra of an “empty” filter, a filter with a carbon nanotubes layer without pumping, and an optically pumped carbon nanotubes layer filter at a wavelength of 980 nm were measured by terahertz time-domain spectroscopy. Main Results. We have shown by experiments that optical pumping of a filter with carbon nanotubes layer leads to a decrease in the transmittance of the main resonance peak and a shift towards

The work is dedicated to design of epsilon-near-zero metamaterials (ENZ) in terahertz frequency range. Two materials were investigated: the first material is the one-layered single-wire medium (SWM) and the second material consists of the planar parallel metal stripes on the layer of polyethylene terephthalate (PET). The wired medium was designed using analytical approximation of thin wire structures and verified by numerical simulations. The striped metamaterial was designed using numerical simulations software and its performance was experimentally verified by terahertz time-domain spectroscopy.

The paper considers the stability and degradation of holograms recorded in the photopolymerized nanocomposite both during storage and under external influences –heating up to the glass transition temperature of the polymer matrix and exposure to ultraviolet radiation. The compositions with different nanoparticles are compared; the difference in the thermal stability of the recorded holograms is shown; the optimum component ratios ensuring the lowest degradation are found. Holograms are recorded on a nanocomposite material that is a liquid photocurable monomer composition containing ZnO or SiO2 nanoparticles and photosensitizers.

Demonstrations of specific class of materials with extremely small (near zero) values of permittivity have attracted attention of scientific community. These unique materials have the refractive index equal to zero what causes almost constant spatial distribution of the electric field of the propagating wave inside these media. Considering its extreme properties, ENZ-material can also be used as delay line that brings no phase delay in propagating wave, as ideal coupler between waveguides of the same diameter and can find effective application in cloaking. It should be mentioned that ENZ-, MNZ(“mu near zero”) and LH(‘left-handed”) materials can be designed using transformation optics approximation. ENZ or MNZ coating may be used to radically enhance transmission through subwavelength aperture in planar ideally opaque screen which allow to overcome the diffraction limit. In general, isolated subwavelength aperture can’t provide enough transfer of energy, but with ENZ coating the transfer increases by several orders of magnitude. This work is dedicated to zero-index (ZI) terahertz metamaterial designed with one-layer aligned planar aluminum wires on dielectric PET substrate and acting like epsilon-near-zero (ENZ) medium. Metal stripes on dielectric substrate can be easily manufactured. The idea is that metal stripes may have permittivity described by Drude model in terahertz frequency range, what gives the opportunity to design ENZmaterial.

Protective elements formed in a 3D hologram recorded in a polymer nanocomposite, such as a lens hologram, a cryptographic information lens hologram, a hologram with a hidden cryptographic image invisible to the naked eye, and a transmissive element based on the volume hologram of the flat body, are studied. Holograms are recorded on a nanocomposite material that is a photopolymerization monomer composite containing various photosensitizers and nanoparticles.

Highly selective volume-diffraction gratings are recorded on a holographic acrylate nanocomposite. The holographic characteristics of the gratings are studied. It is shown that the diffraction efficiency of gratings can reach 50% and a 3D hologram is formed. The refractive index modulation is 0.048–0.065.