Maria I. Fokina

Microelements with High Aspect Ratio Prepared by Self-Focusing of Light at UV-Curing

The results of deep lithography based on the long-wavelength UV photopolymerization with a light self-focusing effect are presented. The effect of the formation of “bridges” between the nearest photopolymerization areas is revealed. Its sources such as the inhibition of photopolymerization by oxygen due to its diffusion to the exposed area are discussed. The conditions for a high aspect ratio of microelements (up to 100) are determined.

Forming lattices of microlenses by the method of dosed photopolymerization of UV-hardened optical composites

This paper discusses two processes for forming microstructures, based on selective photopolymerization of a composite and the volume-reduction effect of a composite when it undergoes photopolymerization. Both processes belong to the group of grey-scale lithography methods and make it possible to accurately form the surface of microlenses when the optical density distribution of a photomask over the radius of the microlens is given.

Organic noncentrosymmetric complexes of 4-nitrophenol for second harmonic generation

The paper reports synthesis and co-crystallization of 5 co-crystal of 4-nitrophenol (4N) with five different monoand diaminopyridines (4-aminopyridine (4AP); 3,4-diaminopyridine (34DAP); 2-amino-6-methylpyridine (26MAP); 2,6- diaminopyridine (26DAP); 2-aminopyridine (2AP)) resulted in five adducts with the molar ratio of components 2:1 in final compounds. X-ray analysis confirms the non-centrosymmetric packing of obtained compounds. Two compounds crystallize in the polar acentric P21 and three compounds crystallize in acentric orthorhombic Pna21 space groups. The comparative studies on the laser induced multiple and single shot damage thresholds of named crystals were carried out using radiation of 1064 nm from Nd:YAG laser with pulse width 10 ns. Obtained results show good laser-induced singleshot and multiple-shot damage threshold values for all studied co-crystals and are found up to 3.64 GW/cm2 and 1.77 GW/cm2 respectively.

An electro-optic polymer modulator for radio photonics

A method for developing an electro-optic polymer Mach‒Zehnder modulator based on polymethylmethacrylate- disperse red copolymer has been investigated. The inverse scheme is chosen as the basis for preparing a microstrip structure. This scheme entails the formation of microgrooves in the lower cladding layer by combining photolithography and reactive-ion etching (RIE), with subsequent deposition of an active electro-optic layer by centrifugation. The processes of forming layers and electrodes, the interaction between layers, the light transmission through the microstrip structure, and the modulator characteristics are considered.

N,N-Diethyl-4-[(E)-(pyridin-3-yl)diazen­yl]aniline

The molecule of the title compound, C15H18N4, adopts a trans conformation with respect to the diazo N=N bond. The dihedral angle between the benzene and pyridine rings in the molecule is 8.03 (5)°. In the crystal, a weak C—H⋯π interaction arranges the molecules into a corrugated ribbon, with an antiparallel orientation of neighboring molecules propagating in the [100] direction.

Refractometric Parameters of Nonlinear Optical Molecular Cocrystals Based on the Aminopyridine Series

Refractive indices of new nonlinear optical materials based on 4-nitrophenol cocrystals with the aminopyridines 2-aminopyridine, 2,6-aminopyridine, and 4-aminopyridine have been studied. The refractive indices of the compounds under study are presented: n = 1.694 (optical microscopy) and 1.605 (Abbe method) for 2-aminopyridine-4-nitrophenol (2AP4N), n = 1.541 (optical microscopy) and 1.589 (Abbe method) for 2,6-diaminopyridine-4-nitrophenol (2,6DAP4N), and n = 1.561 (optical microscopy) and 1.591 (Abbe method) for 4-aminopyridine-4-nitrophenol (4AP4N).

Antifungal activity of ZnO, SiO2, Au and Ag acrylic nanocomposites

The paper describes our results on antifungal effect of nanocomposite material. The nanocomposite is based on acrylates and functional nanoparticles composition. The study of material activity was carried out by the agar diffusion method. Candida albicans (C. albicans) strain of fungi was used as a test object. The antifungal effect of polymer matrix is shown. Zinc oxide nanoparticles increase the antifungal effect.

Optical radio-photonic channel for transmission of a coherent narrowband analog signal

The channel of an optical transmission line of coherent narrowband analog signal consisting of a continuous-wave laser, an electro-optic modulator, and a vector phase rotator based on electrically controlled fiber-optical 1 × 2 splitter and fixed delay lines is analyzed. The scheme is constructed from commercially available components used in digital optical communication systems. The applicability of components for analog and small-signal circuits is determined. Variation of radio signal phase in the range from 0° to 170° for radio signal frequencies between 1 and 2 GHz is demonstrated experimentally. It is shown that phase variation is a linear function of frequency in this range.