Modeling of the spectrum in a random distributed feedback fiber laser within the power balance modes

The simplest model for a description of the random distributed feedback (RDFB) Raman fiber laser is a power balance model describing the evolution of the intensities of the waves over the fiber length. The model predicts well the power performances of the RDFB fiber laser including the generation threshold, the output power and pump and generation wave intensity distributions along the fiber. In the present work, we extend the power balance model and modify equations in such a way that they describe now frequency dependent spectral power density instead of integral over the spectrum intensities. We calculate the generation spectrum by using the depleted pump wave longitudinal distribution derived from the conventional power balance model. We found the spectral balance model to be sufficient to account for the spectral narrowing in the RDFB laser above the threshold of the generation

Generation of spatio-temporal extreme events in noise-like pulses NPE mode-locked fibre laser

We experimentally study spatio-temporal generation of extreme events in the radiation of NPE mode-locked fibre laser generating noise-like pulses. We show that new pulses starts from high-intensity spatio-temporal structure which consist of mainly 3 subsequent pulses which are both separated over fast and slow evolution time. Statistical analysis of the noise-like pulse evolution over round-trips shows that the pulse width and intensity varies with a period of around 85 round-trips which does not change from pulse to pulse. The intensity probability density function has a heavy tail originated only from events of pulse formation

Revealing spectral cross-correlations in radiation of multiwavelength fiber laser with randomly distributed feedback

In present paper correlations between different parts of spectrum of a fiber laser with randomly distributed feedback (RDFL) were experimentally measured directly. Implemented statistical analysis demonstrate weak cross-correlations between different lines in generation spectrum. These correlations were vizualized by plotting 2-D probability density functions. Linear correlation coefficient (Pearson coefficient) was calculated for each pair of spectrum lines

Волокнистая масса для изготовления офортной бумаги

У статті розглядається можливість використання модифікованих волокон на основі целюлози, як добавку, в композиційному складі волокнистої маси при виготовленні паперу для друку офортів.In the article the possibility of the use of the modified fibres on the basis of cellulose is considered, as addition, in composition of fibred mass at making of paper for printing of etching.В статье рассматривается возможность использования модифицированных волокон на основе целлюлозы, как добавку, в композиционном составе волокнистой массы при изготовлении бумаги для печати офортов

Assessment of the maturity level of the customer relationship management system

The article proposes the authors’ method for assessing the maturity of the customer relationship management system of a company. The purpose of the article is a theoretical refinement of the concept of customer relationship management in terms of expanding the conceptual apparatus and defining the stages of the customer-centric transformation process. The achieve the indicated purpose, the following methods were used: systematisation of existing scientific views on the research topic; analysis and refinement of models for quantitative interpretation of customer and expert survey data; identifying trends in competitive market conditions in terms of customer centricity. The topic is relevant due to several factors: competition based on the aggregate value provided is one of the main ways to compete in the market in current circumstances; the conceptual apparatus used today to analyze customer centricity is neither uniform nor sufficient; established scientific vision of customer-centric transformation does not include the understanding of this process’ levels and stages. The authors of the article created a new thesaurus by proposing to introduce certain concepts of customer-centric transformation and maturity of the customer relationship management system. Maturity factors and levels were analyzed. For practical purposes, existing methods of measuring the maturity of a customer relationship management system are studied, practical recommendations aimed at increasing the level of maturity are prepared, and potential risks are identified. It is demonstrated that the maturity of the customer relationship management system is the level of systemic understanding and practical implementation of the principles of customer-centric transformation

Influence of Kerr nonlinearity on PT-transition in coupled fibre lasers

This work investigates a concept of coupled fiber lasers exhibiting PT-symmetry and a PT-transition between PTsymmetric and PT-broken lasing states. We consider a system operated via Raman gain comprising two fiber loops (ring cavities) connected to each other by means of two fiber couplers with adjustable phase shift between them. By changing the phase shift or/and amplification (loss) in fiber loops, one can switch between generation regimes, realizing either PTsymmetric or PT-broken solution. In the PT-symmetric lasing regime, equal powers are generated in both cavities despite only active one is pumped. We make theoretical and numerical description of the proposed coupled fiber lasers starting with the simple discrete matrix model taking into account coupling, phase delays, gain (which is assumed to be saturated), losses and nonlinear phase shift. We show how the PT-transition is affected by self-phase modulation inside the fiber cavity and investigate requirements that should be met in order to observe PT-transition experimentally despite Kerr effect that violates exact symmetry conditions. In particular, we show that PT-transition may be observable only near lasing threshold. Further on we adopt more sophisticated model based on Nonlinear Schrödinger equation for PT fiber laser. Taking into account quasi-CW polychromatic radiation with typical spectral bandwidth of fiber Raman lasers, chromatic dispersion and Kerr nonlinearity, we demonstrate both PT-symmetric and PT-broken lasing in a fiber laser

Автоматизация определения оптических характеристик фотополимерных композиций УФ-лаков и лакированных оттисков

Розроблено структуру системи для автоматизації вимірювання і статистичного визначення коефіцієнта пропускання і оптичної густини фотополімерних композицій УФ-лаків і лакованих відбитків із застосуванням программно-апаратних засобів з проблемною орієнтацією.The structure of the system is developed for automation of measuring and statistical determination of coefficient of admission and optical closeness of photopolimer compositions of ultraviolet varnishes and lacquered prints with the use of software and hardware facilities with the problem orientation.Разработана структура системы для автоматизации измерения и статистического определения коэффициента пропускания и оптической плотности фотополимерных композиций УФ-лаков и лакированных оттисков с применением программно-аппаратных средств с проблемной ориентацией

Self-Induced Faraday Instability Laser

We predict the onset of self-induced parametric or Faraday instabilities in a laser, spontaneously caused by the presence of pump depletion, which leads to a periodic gain landscape for light propagating in the cavity. As a result of the instability, continuous wave oscillation becomes unstable even in the normal dispersion regime of the cavity, and a periodic train of pulses with ultrahigh repetition rate is generated. Application to the case of Raman fiber lasers is described, in good quantitative agreement between our conceptual analysis and numerical modelin

Spatial location of correlations in a random distributed feedback Raman fiber laser

Nonlinear interactions between different components of multiwavelength radiation are one of the main processes shaping properties of quasi-CW fiber lasers. In random fiber lasers, nonlinear influence may be more complicated, as there are no distinct longitudinal modes in radiation because of the random nature of the feedback. In this Letter, we experimentally characterize internal correlations in the radiation of a multiwavelength random distributed feedback fiber laser. An analysis of Pearson correlation functions allows us to spatially locate the area over the fiber laser length in which correlations are more likely to occur. This, in turn, leads us to the conclusion about the main mechanism of spectral correlations—the relative intensity noise transfer from the pump wave