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V. L. Kalashnikov

Publications and source records attributed to V. L. Kalashnikov.

At least 37 records · Page 2Linked to original sources
arXiv2010

Soliton absorption spectroscopy

We analyze optical soliton propagation in the presence of weak absorption lines with much narrower linewidths as compared to the soliton spectrum width using the novel perturbation analysis technique based on an integral representation in the spectral domain. The stable soliton acquires spectral modulation that follows the associated index of refraction of the absorber. The model can be applied to ordinary soliton propagation and to an absorber inside a passively modelocked laser. In the latter case, a comparison with water vapor absorption in a femtosecond Cr:ZnSe laser yields a very good agreement with experiment. Compared to the conventional absorption measurement in a cell of the same length, the signal is increased by an order of magnitude. The obtained analytical expressions allow further improving of the sensitivity and spectroscopic accuracy making the soliton absorption spectroscopy a promising novel measurement technique.

physics.optics↗
arXiv2009

Spatially-temporal dynamics of a passively Q-switched Raman-active solid-state oscillator

The spatially-temporal model of an all-solid-state passively Q-switched oscillator with an active medium providing the stimulated Raman scattering is presented. The model does not presume a Gaussian shape of the cylindrically symmetric modes at both fundamental and Stokes wavelengths. It is found, that the highly-nontrivial spatially-temporal dynamics can be regularized by the optimal choice of the oscillator parameters, viz. initial transmission of a saturable absorber, curvature of a spherical mirror, and output mirror transmission at the fundamental and Stokes wavelengths. As a result, the pulse can be substantially temporally squeezed and spatially broadened at both fundamental and Stokes wavelengths.

physics.optics↗
arXiv2009

Chirped dissipative solitons of the complex cubic-quintic nonlinear Ginzburg-Landau equation

Approximate analytical chirped solitary pulse (chirped dissipative soliton) solutions of the one-dimensional complex cubic-quintic nonlinear Ginzburg-Landau equation are obtained. These solutions are stable and highly-accurate under condition of domination of a normal dispersion over a spectral dissipation. The parametric space of the solitons is three-dimensional, that makes theirs to be easily traceable within a whole range of the equation parameters. Scaling properties of the chirped dissipative solitons are highly interesting for applications in the field of high-energy ultrafast laser physics.

physics.optics↗
arXiv2009

Chirped-pulse oscillators: a unified standpoint

A completely analytical and unified approach to the theory of chirped-pulse oscillators is presented. The approach developed is based on the approximate integration of the generalized nonlinear complex Ginzburg-Landau equation and demonstrates that a chirped-pulse oscillator is controlled by only two parameters. It makes it easy to trace spread of the real-world characteristics of both solid-state and fiber oscillators operating in the positive dispersion regime.

physics.optics↗
arXiv2007

Quantum mechanics of the closed collapsing Universe

Two approaches to quantization of Freedman's closed Universe are compared. In the first approach, the Shrodinger's norm of the wave function of Universe is used, and in the second approach, the Klein-Gordon's norm is used. The second one allows building the quasi-Heisenberg operators as functions of time and finding their average values. It is shown that the average value of the Universe scale factor oscillates with damping and approaches to some constant value at the end of the Universe evolution.

gr-qc↗
arXiv2007

Universe driven by the vacuum of scalar field: VFD model

It is shown that in the Vacuum Fluctuations Domination model (VFD), where vacuum fluctuations of scalar fields dominates under matter and radiation throughout the all history of the Universe expansion (arXiv:gr-qc/0604020, arXiv:gr-qc/0610148), acceleration parameter evolves monotonically from the zero to the present day negative value. That is according to this model the Universe has no decelerating past and conventional radiation domination and matter domination epochs are absent. Predictions of accelerating parameter for z~0-2 is compared with that follows from the SN type Ia data.

astro-ph↗
arXiv2007

Determination of the UV cut-off from the observed value of the Universe acceleration

It is shown that using of the equation of motion of the Universe scale factor allows calculation of the contribution of the vacuum fluctuations to the acceleration of the Universe expansion. Renormalization of the equation is needed only in the case of massive particles. Under a known number of the different kinds of fundamental fields, this provides determination of momentum of the ultraviolet cut-off from the observed value of acceleration.

gr-qc↗
arXiv2006

Decelerating and accelerating back-reaction of vacuum to the Universe expansion

Back-reaction of the massless scalar field vacuum to the Universe expansion is considered. Automatic renormalization procedure based on the equations of motion instead of the Friedman equation is used to avoid the cosmological constant problem. It is found, that the vacuum tends to decelerate an expansion of Universe if the conformal acceleration of Universe is equal to zero. In contract, the vacuum acts as the true cosmological constant in Universe expanding with the present day acceleration. Estimation for third derivative of the Universe scale factor with respect to conformal time is presented.

gr-qc↗
arXiv2006

Quantum evolution of the Universe in the constrained quasi-Heisenberg picture: from quanta to classics?

The quasi-Heisenberg picture of minisuperspace model is considered. The The quasi-Heisenberg picture of minisuperspace model is considered. The suggested scheme consists in quantizing of the equation of motion and interprets all observables including the Universe scale factor as the time-dependent (quasi-Heisenbeg) operators acting in the space of solutions of the Wheeler--DeWitt equation. The Klein-Gordon normalization of the wave function and corresponding to it quantization rules for the equation of motion allow a time-evolution of the mean values of operators even under constraint H=0 on the physical states of Universe. Besides, the constraint H=0 appears as the relation connecting initial values of the quasi-Heisenbeg operators at $t=0$. A stage of the inflation is considered numerically in the framework of the Wigner--Weyl phase-space formalism. For an inflationary model of the ``chaotic inflation'' type it is found that a dispersion of the Universe scale factor grows during inflation, and thus, does not vanish at the inflation end. It was found also, that the ``by hand'' introduced dependence of the cosmological constant from the scale factor in the model with a massless scalar field leads to the decrease of dispersion of the Universe scale factor. The measurement and interpretation problems arising in the framework of our approach are considered, as well.

gr-qc↗
arXiv2005

Quantum evolution of the Universe from $τ=0$ in the constrained quasi-Heisenberg picture

The Heisenberg picture of the minisuperspace model is considered. The suggested quantization scheme interprets all the observables including the Universe scale factor as the (quasi)Heisenberg operators. The operators arise as a result of the re-quantization of the Heisenberg operators that is required to obtain the hermitian theory. It is shown that the DeWitt constraint H=0 on the physical states of the Universe does not prevent a time-evolution of the (quasi)Heisenberg operators and their mean values. Mean value of an observable, which is singular in a classical theory, is also singular in a quantum case. The (quasi)Heisenberg operator equations are solved in an analytical form in a first order on the interaction constant for the quadratic inflationary potential. Operator solutions are used to evaluate the observables mean values and dispersions. A late stage of the inflation is considered numerically in the framework of the Wigner-Weyl phase-space formalism. It is found that the dispersions of the observables do not vanish at the inflation end.

gr-qc↗
arXiv2004

Perturbations of the spherically symmetric collapsar in the relativistic theory of gravitation: axial perturbations. I

Horizon solutions for the axial perturbations of the spherically symmetric metric are analyzed in the framework of the relativistic theory of gravitation. The gravitational perturbations can not be absorbed by the horizon that results in the excitation of the new type of the normal modes trapped by the Regge-Wheeler potential. The obtained results demonstrate testable differences between the collapsar and the black hole near-horizon physics.

gr-qc↗
arXiv2003

FORTRAN-codes for an analysis of the ultrashort pulse propagation

Short description of the FORTRAN-codes for an analysis of the ultrashort pulse dynamics is presented. We consider: 1) the aberration-less approximation and the momentum method for the search of the single pulse stability regions in the laser with the soft-aperture Kerr-lens mode locking; 2) the distributed complex Ginzburg-Landau model for the same aim; 3) the generalized Schroedinger equation for the analysis of the femtosecond pulse propagation in the tapered and photonic crystal fibers.

physics.comp-ph↗
arXiv2002

Quintessential Cosmological Scenarios in the Relativistic Theory of Gravitation

It is shown that the accelerated expansion of the universe in the framework of the relativistic theory of gravitation can be achieved by the introduction of the quintessential term in the energy-momentum tensor. The value of the minimum scaling factor and the modern observational data for the density and state parameters of the matter give the rough estimations for the maximum graviton mass and the maximum scaling factor. The former can be very low in the case of the primordial inflation and the latter can be extremely large for the scalar field model of the quintessence. In any case, the massive graviton stops the second inflation and provide the closed cosmological scenario in the agreement with the causality principle inherent to the theory.

gr-qc↗
arXiv2002

Mathematical ultrashort-pulse laser physics

The analytical and numerical approaches to the analysis of the ultrashort-pulse solid-state lasers are presented. The unique self-consistent method of the laser dynamics analysis is based on the symbolical, numerical, programming, and graphical capacities of Maple 6. The algorithmization of the basic conceptions as well as sophisticated research methods is of interest to both students and experts in the laser physics and the nonlinear dynamics

physics.optics↗
arXiv2001

X-matter induced cosmological scenarios in the relativistic theory of gravity

It was shown, that the presence of the so-called X-matter with an equation of state, which lies between limits of the strong and weak energy conditions, allows the variety of the cosmological scenarios in the relativistic theory of gravity. In spite of the fixed negative sign of the cosmological term in the field equations with massive graviton, it is possible to obtain the solutions with accelerated and complicated loitering expansion of the universe. The numerical estimation of the universe's age agrees with the modern observational data if the upper limit of the graviton's mass is 10^{-71} g

gr-qc↗