NEW SERIES. SERIES: PHYSICS
ISSN 1817-3020 (Print)
ISSN 2542-193X (Online)


Оптика и спектроскопия. Лазерная физика

Fluorescent nanostructures based on folic acid and citrate: synthesis and properties

Fluorescent nanostructures are of great interest due to their unique properties. Fluorescent nanostructures obtained from organic precursors are usually water-soluble, have low cytotoxicity, and high photostability. One of their advantages is the wide choice of starting materials and the relative simplicity of synthesis. The use of folic acid as a precursor for fluorescent nanostructures opens up the possibility of targeted imaging. This article shows a one-step scheme for synthesizing fluorescent nanostructures from folic acid and citrates.

Нанопрофилометрия при фазочастотной модуляции лазерного автодина

В работе анализируется автодинный интерференционный метод измерения рельефа поверхности при треугольной модуляции длины волны лазерного излучения. Рассматривается случай многочастотной интерферометрии с учетом изменения стационарной фазы автодина и его спектрального представления в области равнофазных расстояний. Получена линейная зависимость амплитуд спектральных составляющих от величины профиля поверхности и определены условия достижения наибольшего разрешения.

MATHEMATICAL ASPECTS OF AIRY STRESS FUNCTION OF A CUBOID CRYSTAL IN PHOTOACOUSTIC CELL

Today, crystalline solids have got practical importance due to their wide industrial applications. In application points of view, crystals of large size and better quality are prepared synthetically. Various techniques are used nowadays to study elastic behavior of different types of crystals. Here, photoacoustic effect has been implemented for stress generation in a cuboid crystal.

Transformation of Eigenvalues of the Zakharov–Shabat Problem under the Effect of Soliton Collision

Background and Objectives: The Zakharov–Shabat spectral problem allows to find soliton solutions of the nonlinear Schrodinger equation. Solving the Zakharov–Shabat problem gives both a discrete set of eigenvalues λj and a continuous one. Each discrete eigenvalue corresponds to an individual soliton with the real part Re(λj) providing the soliton velocity and the imaginary part Im(λj) determining the soliton amplitude. Solitons can be used in optical communication lines to compensate both non-linearity and dispersion.

Distance Measurement with Harmonic Modulation of Self-Mixing Laser Wavelength at External Optical Feedback

Background and Objectives: Self-mixing interferometry of absolute distances is currently well represented by the method of frequency modulation of the laser diode supply current (FMCW). In recent years a harmonic modulation of the power current of a self-mixing laser began to be used. The advantage of the harmonic modulation method is due to the absence of the need to adjust the deviation of the radiation wavelength when changing the distance to the reflector.

ПРЕОБРАЗОВАНИЕ СОБСТВЕННЫХ ЗНАЧЕНИЙ ЗАДАЧИ ЗАХАРОВА-ШАБАТА ПРИ СТОЛКНОВЕНИИ СОЛИТОНОВ

Представлены результаты численного анализа преобразования солитонных импульсов, подчиняющихся модифицированному нелинейному уравнению Шредингера с изменяющимися коэффициентами. Основное внимание уделяется процессу трансформации собственных значений задачи Захарова-Шабата. Собственные значения характеризуют групповую скорость солитона и его амплитуду. В работе рассмотрено столкновение двух синфазных солитонов первого порядка.

Numerical Modeling of the Opposite Waves Spatio-Temporal Dynamics in a Ring Fibre Nonlinear Microcavity

Background and Objectives: Optical frequency combs have a significant impact in the terabit communications area. Kerr frequency comb generation in the nonlinear microcavities is especially promising because it allows for creation of the combs with spacings of tens of gigahertz between the frequencies. However, such combs can also spawn strong phase noises, what, in turn, leads to the problems with the high-speed data transmission.

Specificity of the Mathematical Modeling of Light Fields in a Sensing Element for the Fiber-Based Evanescent-Wave Mid-IR Spectroscopy

Background and Objectives: The fiber-based evanescent-wave mid-IR spectroscopy is a prospective tool for the real-time remote chemical analysis of various substances, which have their vibrational spectra in the mid-IR spectral range. Chalcogenide fibers transparent in the mid-IR are considered as the most suitable sensing elements of the fiber-based mid-IR spectroscopic sensors.

Method for Measuring Acceleration by the Spectrum of Self-Mixing Signal of Semiconductor Laser

Background and Objectives: Traditional methods for measuring the acceleration by changing the position of extremums on the time axis, as well as methods based on the use of least squares and wavelet analysis, require significant signal processing efforts: filtering and allocating extremums or significant time for processing an autodyne signal.

Referenceless Low-Coherence Reflectometry of Random Media under Wide-Band Spectral Selection of Scattered Probe Light

Background and Objectives: The optical probes of randomly inhomogeneous media, based on analysis of the statistical parameters of the scattered light intensity, are sensitive to optical, structural, and transport parameters of the medium. A promising approach among the low-coherence optical methods is an approach in which the medium is considered as a multi-beam interferometer with randomly distributed values of the path difference of the interfering beams (partial waves).

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