ISSN 1817-3020 (Print)
ISSN 2542-193X (Online)

Оптика и спектроскопия. Лазерная физика

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.


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).

Methods of Digital Holography in Interference Microscopy of Reflective Object in Partially Coherent Light

The theoretical foundation of the possibility of using the interference microscopes with extended and frequency broadband light source for recording digital holograms of microscopic objects, reconstruction and visualization of phase images is presented. Numerical procedure for processing of spatially localized digital holograms of the focused image in a partially coherent light are considered. Results of experiments on digital holographic microscopy of biological objects in a partially coherent light with Linnik interference microscope are shown.

Optical Soliton Inelastic Interacitons in Nonlinear Schrödinger Equation with Variable Coefficients Model

It is shown that in systems described by nonlinear Schrödinger equation with variable coefficients, interaction of two solitons can carry an inelastic character. Inelastic collision solitons can lead to changes in their group velocities, amplitudes and durations. We consider some particular cases related to the separation of the soliton pair and formation of a bound state of two solitons. In the applied aspect these phenomena can be used to control the soliton interaction in optical fiber communications.

Dynamic Light Scattering Method in Studies of Silica and Gold Nanoparticles

Background and Objectives: It is well known, that uncritical use of the dynamic light scattering (DLS) method may give unacceptable results for the volume or number distributions of particles as compared with transmission electron microscopy (TEM) data. The purpose of this study is to investigate application of the DLS method for determining the size of colloidal silica and gold nanoparticles and to compare results of three methods: DLS, TEM, and absorption spectroscopy (see next paper).

Application of Dynamic Light Scattering and Absorption Spectroscopy to Studies of Systems with Colloidal Gold Nanoparticles + DNA

Background and Objectives: The dynamic light scattering (DLS) method is widely used to evaluate the particle size distributions. However, DLS is not free of serious drawbacks. For a fast approximate estimation of the average size of colloidal gold nanoparticles (AuNPs) within the range of 15–100 nm reasonable results can be obtained with using the absorption spectroscopy. We discuss the advantages and drawbacks of DLS, transmission electron microscope (TEM), and absorption spectroscopy in gold nanoparticle sizing.