Alexei Meshalkin

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• Doctor of Philosophy
• Scientific Officer at Moldova State University

In the present study, the photosensitive nanocomposite was fabricated based on azopolymer and Au nanoparticles (Azo-Au NPs). For the first time, the synthesized polymeric poly-N-(2,3-epoxypropyl) carbazole with azo dye SY 3 (PEPC-co-SY 3) was the basis of the nanocomposite. As a medium for polarization holographic recording, thin films of a nanocom...

Photo-induced anisotropy measurements were carried out in thin films of azopolymers PEPC with Solvent Yellow 3, with the concentrations of 10 wt% and 30 wt% of polymers with azo groups in their side-chain. The experimental dependences of the azimuths of the probe beam at the pump beam angles for samples were studied. The photoinduced dependence of...

In poly-N-epoxypropylcarbazole films containing 10 wt % CHI3 as an additive, diffraction gratings with a period of about 1 μm have been recorded by electron-beam irradiation at various radiation doses. The influence of the duration of storage in the dark of diffraction gratings on their diffraction efficiency has been examined. A postradiation incr...

The results on using of carbazole-based azopolymer layers (Polyepoxypropylcarbazole:Methyl Red with magnetic particles of Fe2SO4) for the recording of 1-D and 2-D surface relief gratings are presented in this report. Morphology study using AFM and MFM of obtained structures has shown their good quality. Surface relief gratings with profile height u...

It is well known that azobenzene-containing polymers (azopolymers) are sensitive to the polarization orientation of the illuminating radiation, with the resulting photoisomerization inducing material transfer at both the meso- and macroscale. As a result, azopolymers are efficient and versatile photonic materials, for example, they are used for the...

We discuss methods for synthesis and fabrication of photosensitive thin azopolymer films. Spectroscopy of films presents information as about nonactinic and recording wavelengths as a for refraction index calculations by Swanepoil method. Photoinducing of anisotropy was done by blue laser. The resulting polarimetric light parameters produced by pho...

This paper is devoted to the investigations of the recording of 1-D and 2-D holographic gratings using thin films of polyepoxypropylcarbazole (PEPC) obtained by deposition from solutions and their use as registering media for. For the direct recording azopolymer films based on polyepoxypropylcarbazole: methyl red with magnetic particles of Fe2SO4 w...

It is well known that azobenzene-containing polymers (azopolymers) are sensitive to the polarization orientation of the illuminating radiation, with the resulting photoisomerization inducing material transfer at both the meso-and macroscale. As a result, azopolymers are efficient and versatile photonic materials, for example, they used for the fabr...

The energy and spectral conditions for single-stage holographic recording of a diffraction optical element based on the carbazole-containing azo polymer, that forms singular light beams (optical vortices), have been established. With the atomic-force microscopy (AFM), the surface morphology of the recorded relief holograms was studying, and their d...

We demonstrate an easy two-step maskless method for the fabrication of so-called compound fork-shaped gratings in nanomultilayer structures (NMLSs) based on chalcogenide glasses. Such elements allow one to generate different configurations of optical vortex (OV) beams with given topological charges (TCs). The used NMLS is particularly interesting b...

Direct fabrication of complex diffractive optical elements (DOEs) on photosensitive thin films is of critical importance for the development of advanced optical instruments. In this paper, we design and investigate DOEs capable of generating optical vortices. Analog and digital approaches for one-step polarization holographic recording of vortex DO...

Представлено одно- и двулучевое формирование дифракционных микроструктур в пленках карбазолсодержащего азополимера. Показана возможность записи единичных микронеровностей сфокусированным вихревым лазерным пучком с линейной и круговой поляризацией. Проведен анализ формы рельефа микроструктур от состояния поляризации. Представлен двулучевой метод соз...

The analysis of dependence of diffraction efficiency on number of grooves of phase gratings with square and sine profiles was performed by means of diffraction modeling using angular spectrum method. Phase gratings with different number of grooves from 1 to 100 was modeled and diffraction efficiency was estimated from the obtained diffraction patte...

In this work, the formfactor influence on the diffraction efficiency of 2D and 3D phase holograms was analyzed. Experimental results showed that holograms recorded in a chalcogenide glassy semiconductor and an azopolymer have limitations on maximum achievable diffraction efficiency. The coefficient of optimal exposure increase that is necessary to...

The analysis of dependence of diffraction efficiency on number of grooves of phase gratings with sinusoidal profile was performed by means of specially designed program. An Angular Spectrum method applied for monochromatic light propagation in far field through phase grating was used for calculation of diffraction efficiency of gratings. Diffractio...

In this paper we report on direct holographic recording of surface relief gratings in carbazole-based polymers. Evolution of the transmittance spectrum and diffraction efficiency upon irradiation with 532 nm laser light demonstrated the photo-induced surface patterning of gratings.

This paper describes a direct holographic recording of surface relief gratings in QD doped carbazole-based polymers. The evolution of the transmittance spectrum and diffraction efficiency upon irradiation with 473 nm polarized laser light demonstrated the photo-induced surface patterning of gratings.

Chalcogenide glasses nanomultilayer structures based on As2S3–Se were used for direct surface relief grating (SRG) formation by holographic recording. Grating recording process in As2S3–Se nanomultilayer structure for different grating period and long recording time was performed. Simulated diffraction efficiency kinetics curves showed good agreeme...

Surface relief diffraction structures composed of two or three superimposed unidirectional gratings with unequal grating periods were produced using the electron beam recording and subsequent chemical etching. Diffraction patterns produced by different diffraction structures were studied. In addition to the main diffracted beams the low-intensity "...

In this paper we report on direct holographic recording of surface relief gratings in carbazole-based azopolymers. Azo dye Disperse Orange 3 was chemically bonded to oligomer poly-N-(epoxypropyl carbazole) making surface deformation efficient in the presence of optical field gradient. Optimal concentration of azo dye and the film thickness were det...

The formation of microstructures on the surface of a carbazole azopolymer occurred with a Gaussian beam of a linearly polarized laser with wavelengths of 405, 485, and 532 nm. Power density was changing. Images of the formed microprotrusions and their parameters were obtained depending on the power density and wavelength. The effect of the waveleng...

The analysis of dependence of diffraction efficiency on duty cycle and modulation depth of phase gratings with rectangular and Gaussian profile was performed by means of specially designed program. An Angular Spectrum method applied for monochromatic light propagation in far field through phase grating was used for calculation of diffraction effici...

The analysis of dependence of diffraction efficiency on duty cycle and modulation depth of phase gratings with rectangular and Gaussian profile was performed by means of specially designed program. An Angular Spectrum method applied for monochromatic light propagation in far field through phase grating was used for calculation of diffraction effici...

В данной работе представлены спектральные зависимости пропускания слоев селена (толщины слоев Se: 630 нм, 1030 нм), изготовленных с помощью метода термического напыления в области 500-900 нм. Из спектров пропускания были получены оптические константы слоев Se: показатель поглощения составляет 9·104 см-1 для записывающей длины волны 532 нм. Использу...

Polarization holographic recording of diffraction gratings and their subsequent erasure have been investigated on As2S3–Se multilayer nanostructures. The work investigates how preexposure to actinic laser radiation up to complete photoinduced changes in the optical properties affects the formation of diffraction gratings in the studied structure. I...

Surface relief gratings and refractive index gratings are formed by direct holographic recording in amorphous chalcogenide nanomultilayer structures and thin films . The evolution of the grating parameters, such as the modulation of refractive index and relief depth in dependence of the holographic exposure, is investigated. Off-axis digital hologr...

The topography of surface relief gratings patterned on As2S3–Se nanomultilayers was investigated by digital holographic microscopy. For the high-accuracy phase reconstruction of the topography we used the sparse wavefront modeling. Experimental results are presented.

Direct laser recording of surface relief gratings as phase holograms on successive evaporated As2S3 and Se nanomultilayers was studied in this paper. The surface relief gratings patterned on As2S3-Se nanomultilayers were investigated in dependence on polarization states of recording beams. It was shown that phase gratings are formed on the surface...

Исследован процесс поляризационной голографической записи дифракционных решеток и их последующего стирания в многослойной наноструктуре As2S3-Se. Изучено влияние предварительной засветки актиничным лазерным излучением до полного насыщения фотостимулированных изменений оптических свойств на формирование дифракционных решеток в исследуемой структуре....

Processes of holographic recording of surface relief structures using As2S3:Mn–Se multilayer nanostructures as registering media were studied in this paper. Optical properties of As2S3:Mn, Se layers, and As2S3:Mn–Se multilayer nanostructures were investigated. Values of optical bandgaps were obtained from Tauc dependencies. Surface relief diffracti...

New carbazole-based azopolymer was synthesized, characterized and applied for formation of photoinduced surface relief gratings. The surface modulation of spin-coated azopolymer film depending on the different polarization configurations is considered. It is shown that holographic surface relief gratings with relatively large thickness modulation c...

The focus of this research is on the investigation of structural changes in the As2S3–Se multilayer nanostructure and on the examination of a relative contribution of As2S3 and Se layers to nanostructuring by measuring the Raman spectra. The formation of the As2S3-Se nanostructure by an alternate As2S3 and Se layers deposition was applied. The diff...

Processes of e-beam and holographic recording of surface-relief structures using Ge5As37S58–Se multilayer nanostructures as registering media were studied in this paper. Optical properties of Ge5As37S58, Se layers and Ge5As37S58–Se multilayer nanostructures were investigated. Spectral dependencies of refractive index were analyzed within the frames...

Processes of e-beam and holographic recording of surface relief structures using Ge5As37S58-Se multilayer nanostructures as registering media were studied in this paper. Optical properties of Ge5As37S58, Se layers, and Ge5As37S58-Se multilayer nanostructures were investigated. Spectral dependencies of refractive index were analyzed within the frame...

New carbazole-based azopolymer was synthesized, characterized and applied for formation of photoinduced surface relief gratings. The surface modulation of spincoated azopolymer film depending on the different polarization configurations is considered. It is shown that holographic surface relief gratings with relatively large amplitude could be obta...

Abstract— Properties of nanomultilayer As2S3-Mn systems and peculiarities of holographic gratings recording with their use are considered in this report. Optical constants were obtained from transmission data, spectral dependencies were analyzed within the frames of single oscillator model. Holographic gratings with spatial frequencies 1600 mm-1 w...

For the first time direct one-step relief formation of holographic grating with the use of amorphous chalcogenide nanomultilayers of new composition based on Ge5As37S58–Se was studied. Amorphous Ge5As37S58–Se nanomultilayers were prepared by cyclic thermal vacuum deposition. Optical constants of Ge5As37S58–Se nanomultilayers, Ge5As37S58 and α-Se fi...

Recently polymer materials with azodyes become attractive materials for holographic recording due to possibility of surface relief grating fabrication with high diffraction efficiency and resolution. Large surface modulation (greater than 300 nm) and high diffraction efficiency (greater than 30%) could be obtained under optimal recording conditions...

This paper presents the study of Vickers microhardness performed on a styrene-butyl methacrylate-methylacrylic acid copolymer and the analogous obtained by grafting with ampicilline. The creep properties and the glass transition temperature of the copolymers were investigated. The determination of hardness by micropenetration (Vickers microhardness...

Recently polymer materials with azodyes become attractive materials for holographic recording due to possibility of surface relief grating fabrication with high diffraction efficiency and resolution. Large surface modulation (greater than 300 nm) and high diffraction efficiency (greater than 30%) could be obtained under optimal recording conditions...

This work is devoted to fabrication of the carbazole-containing polymer thin films by spin-coating and their use as recording media for production of holographic diffraction gratings. Polyepoxypropilcarbazole (PEPC) was chosen as polymer material. AFM microscopy-assisted investigations of surface morphology of the obtained films have shown good qua...

The technology of synthesis of bulk samples and deposition of thin films of stoichiometric lead telluride and with antimony impurities in different concentrations are described. The optical properties of the films were studied and value of the band gap on the basis of the received graphical dependencies were calculated by the method of Tauc.

Transparent thin films of polyepoxypropylcarbazole polymer were produced using spin-coating technique. Optical materials constants such as refractive index of thin films and thickness were determined by optical spectroscopy. It was shown the possibility of variation of film thickness by polymer concentration in solution. It was shown that film thic...

The transmission spectra of bulk and thin films of (As2S1.5Se1.5)1-x:Snx in the visible and near infrared (IR) regions were investigated. Doping of As2S1.5Se1.5 chalcogenide glass with tin impurities essentially reduce the absorption bands of SH (Se-H) and H2O located at ν = 5190 cm-1 and ν = 3617 cm-1, respectively. The amorphous As2Se3:Snx and (A...

This paper deals with the interferometric thickness measurements of the spin-coated submicrometer polymer films based on polyepoxypropylcarbazole. The measuring system including the conventional microinterferometer MII-4 with attached webcamera and software for the high precision measurement of the submicrometer thicknesses of films was designed an...

The research of polymer materials with advanced performance for information recording is an active branch in material science and photonics. The series of carbazole-containing compounds: poly-epoxypropylcarbazole (PEPC), poly-epithiopropylcarbazole (PETPC), and copolymers of PETPC:glycidyl butyrate (PETPC:GB) were synthesized and investigated. The...

Исследованы структура и электрохимические свойства полиэтилентерефталатных трековых мембран, на одну из сторон которых методом полива наносили раствор сополимера из стирола и бутилметакрилата. Установлено, что формирование селективного слоя сополимера в порах исходной мембраны приводит к созданию композитных мембран, обладающих в растворах электрол...

The structure and electrochemical properties of polyethylene terephthalate track-etched membranes were studied. The membranes were covered with a solution of a styrene-butylmethacrylate copolymer on one side. The formation of a selective layer of copolymer in the pores of the starting membranes led to composite membranes characterized by asymmetric...

The optical properties of chalcogenide glasses present a great scientific interest for the establishment of the general legitimacy of interaction of the optical irradiation with the amorphous solids, as well as a practical interest. The effect of light-induced photostructural transformations in amorphous chalcogenides films have been initiated many...

The invention relates to a process for obtaining a heterogenous ring compound of the indole derivatives, namely to a process for obtaining ethyl-5-hydroxy-1,2-dimethyl-1H-3-indolcarboxy-late, used for treatment of cardiovascular diseases, particularly hypertension. The process includes the separate preparation of equimolar solutions of 1,4-benzo-qu...

Thin layers of composite and nanocomposite material based on the amorphous arsenic sulfide and polymer polyvinylpyrrolidone (PVP), received by chemical dissolution As2S3 and composite separately, mixing and deposition on various substrates (silica glass, polyethylene terephthalate and monocrystalline silicon, etc.) have been investigated. Research...

Thin films prepared from chalcogenide glasses and polymers were used in the fabrication of diffractive structures by holographic and electron recording technology.

New composite and nanocomposite materials consisting from amorphous chalcogenide (As2S3, As2Se3) and polymers such as polyvinylalcool (PVA) and polyvinylpyrrolidone (PVP) were prepared by inexpensive and easy coating technique from chemical solution and were investigated. Composite retains many properties of the initial components from which they a...

Sensitometric and holographic properties of photoresist layers made from carbazolylalkyl methacrylate copolymers and polyepoxypropylcarbazole sensitized with triiodomethane and, additionally, spiropyran photochromic compounds were studied. It was found that the introduction of photochromic 6′-bromo-8′-nitro-1,3,3-trimethylindolylspirobenzopyran (8–...

With the purpose of extension of the class of polymer materials and nano-composites polymer-chalcogenide non-crystalline semiconductors (ChNS) for photo-and electron-beam lithography thin films from carbazolyl containing copolymers and nano-composites have been prepared, tested and investigated. Electron-beam and holography recording was processed...

Recently special attention has been given to the problem of the holographic registration of images and information with the purpose of a solution of various scientific and technical problems. It is well known that carbazol containing polymers, for example, poli-N-carbazolylalcoxymethacrylate (poli-CAM), co-polymers CAM, polyepoxypropilcarbazol (PEP...