© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

Soviet Journal of Quantum Electronics

Wavefront reversal in stimulated light scattering in a focused spatially inhomogeneous pump beam

N. B. Baranova, Boris Ya Zel'dovich, Vladimir V. Shkunov

Published May 31, 1978• 21 citations

Abstract

A theoretical analysis is made of stimulated light scattering in a pump beam possessing both fine-structure inhomogeneity (and thus, "gray" divergence) and a continuously varying amplitude and phase envelope due to focusing of the beam with a lens into an unbounded medium. An equation is derived to describe the gain of the pump-reproducing field component, and a solution of this equation, excitable by spontaneous radiation noise, is found in the constant pump field approximation. In this case, the scattered wave is localized in a narrow (compared with the pump wave) near-axial zone and, unlike scattering in a waveguide, the reproduction of the pump wave is partial and dependent on the correlation between the "gray" and diffraction-limited divergence. The disagreement between this theoretical conclusion and the complete reproduction observed earlier experimentally indicates the importance of saturation effects in the scattering of focused beams.

DOI: 10.1070/qe1978v008n05abeh010084

Related papers

Influence of saturation on the quality of wavefront reversal in the case of stimulated scattering of spatially inhomogeneous pump radiation

I Yu Anikeev, Iosif G. Zubarev, С И Михайлов

A theoretical investigation is made of stimulated scattering of spatially inhomogeneous radiation under saturation conditions. A system of kinetic equations describing the interaction between the pump radiation and Stokes waves, correlated and uncorrelated with the exciting field, is derived and solved. A quantitative criterion is derived for the quality of wavefront reversal in the case of generation of Stokes radiation from the spontaneous noise and also in the case of a "Brillouin" amplifier.

Soviet Journal of Quantum Electronics•Jan 31, 1986•7 citations

Theory of wavefront reversal of radiation having a spatially inhomogeneous average intensity distribution

Igor' M Bel'dyugin, Iosif G. Zubarev

A spectral method is used in an attempt to find a unified approach to describe several variants of wavefront reversal in stimulated scattering: in a waveguide and when spatially inhomogeneous and single-mode radiation is focused by a lens. It is found that this involves allowing for a specific correlation between the spatial spectral components in the expansion of the pump field. Approximate solutions are found for the scattered field in these cases.

Soviet Journal of Quantum Electronics•Mar 31, 1982•0 citations

Spatial-polarization wavefront reversal in stimulated scattering of the Rayleigh line wing

Boris Ya Zel'dovich, Tatiana Victorovna Yakovleva

A theoretical analysis is made of wavefront reversal with a spatially inhomogeneous state of polarization of the pump radiation in symmetric trace-free stimulated scattering (backscattering). Mode theory is used to find solutions of the equation for the self-interaction of the pump radiation and also to find four linear indendent solutions for the scattered field having a structure correlated with that of the pump field. The increments for these solutions are determined. It is shown that, in contrast to scalar scattering, in the case of symmetric tracefree scattering (stimulated scattering of the Rayleigh line wing) of completely depolarized pump radiation the solution corresponding to complete spatial-polarization wavefront reversal has the largest increment. Reproduction of the wavefront of the depolarized pump radiation in stimulated forward scattering is discussed.

Soviet Journal of Quantum Electronics•Apr 30, 1980•15 citations

Influence of spatial interference on amplification in stimulated scattering of light

Boris Ya Zel'dovich, Vladimir V. Shkunov

An investigation is made of the wave problem of the stimulated scattering of light in a pump beam comprising a plane wave and a small (in terms of energy) admixture of fluctuating distortions. The existence of interference maxima and minima in the pump wave causes an appreciable (up to twofold) enhancement of the gain of the scattered wave, the form of which reproduces that of the pump field. This effect is associated with the previously observed reversal of the wavefront in the stimulated scattering of light.

Soviet Journal of Quantum Electronics•Nov 30, 1977•3 citations

Brillouin reversal of optical fields with a time-dependent speckle structure

Boris Ya Zel'dovich, E A Nemkova, Vladimir V. Shkunov

An analysis is made of stimulated backscattering in the case when the pump (laser) radiation has a continuous frequency spectrum and a time-dependent (nonfactorizable) speckle structure. The gain increments μ ( p ) and the corresponding specklon solution for a Stokes wave are found in the case of an arbitrary ratio of the widths of the pump line Δω l , and of the stimulated scattering line Γ. These solutions correspond to partial wavefront reversal, i.e., to reversal of the spectral band of the pump radiation within an interval of width of the order of Γ/2 around a certain frequency p . A comparison of the specklon gain increments with the increments for uncorrelated waves makes it possible to determine the conditions for wavefront reversal.

Soviet Journal of Quantum Electronics•Nov 30, 1985•2 citations

Investigation of the forward and backward scattering of spatially noncoherent pump radiation

I Yu Anikeev, A. A. Gordeev, Iosif G. Zubarev +1 more

A new method developed by the authors for the analysis of stimulated scattering of spatially noncoherent radiation is used in a comparative study of the concurrent and opposed interactions of a Stokes field with pump radiation. If there is no correlation between the Stokes and pump waves, the interaction is independent of the relative direction of propagation of the waves. However, if the Stokes and pump waves are correlated, the interaction efficiency depends strongly on the relative directions of the waves. Exact expressions are obtained for the structure of the wave fields and gain increments in the backscattering case and approximate expressions are obtained for the forward scattering. The physical reason for the asymmetry in the amplification is the reproduction by the Stokes signal spectrum of the pump spectrum in the forward scattering case and inversion of this spectrum in the backscattering case. The same reason accounts for a deterioration of the quality of wavefront reversal in the backscattering case compared with the forward scattering.

Soviet Journal of Quantum Electronics•Nov 30, 1984•1 citation

A theoretical analysis is made of stimulated light scattering in a pump beam possessing both fine-structure inhomogeneity (and thus, "gray" divergence) and a continuously varying amplitude and phase envelope due to focusing of the beam with a lens into an unbounded medium. An equation is derived to describe the gain of the pump-reproducing field component, and a solution of this equation, excitable by spontaneous radiation noise, is found in the constant pump field approximation. In this case, the scattered wave is localized in a narrow (compared with the pump wave) near-axial zone and, unlike scattering in a waveguide, the reproduction of the pump wave is partial and dependent on the correlation between the "gray" and diffraction-limited divergence. The disagreement between this theoretical conclusion and the complete reproduction observed earlier experimentally indicates the importance of saturation effects in the scattering of focused beams.

A theoretical investigation is made of stimulated scattering of spatially inhomogeneous radiation under saturation conditions. A system of kinetic equations describing the interaction between the pump radiation and Stokes waves, correlated and uncorrelated with the exciting field, is derived and solved. A quantitative criterion is derived for the quality of wavefront reversal in the case of generation of Stokes radiation from the spontaneous noise and also in the case of a "Brillouin" amplifier.

A theoretical analysis is made of wavefront reversal with a spatially inhomogeneous state of polarization of the pump radiation in symmetric trace-free stimulated scattering (backscattering). Mode theory is used to find solutions of the equation for the self-interaction of the pump radiation and also to find four linear indendent solutions for the scattered field having a structure correlated with that of the pump field. The increments for these solutions are determined. It is shown that, in contrast to scalar scattering, in the case of symmetric tracefree scattering (stimulated scattering of the Rayleigh line wing) of completely depolarized pump radiation the solution corresponding to complete spatial-polarization wavefront reversal has the largest increment. Reproduction of the wavefront of the depolarized pump radiation in stimulated forward scattering is discussed.

An investigation is made of the wave problem of the stimulated scattering of light in a pump beam comprising a plane wave and a small (in terms of energy) admixture of fluctuating distortions. The existence of interference maxima and minima in the pump wave causes an appreciable (up to twofold) enhancement of the gain of the scattered wave, the form of which reproduces that of the pump field. This effect is associated with the previously observed reversal of the wavefront in the stimulated scattering of light.

An analysis is made of stimulated backscattering in the case when the pump (laser) radiation has a continuous frequency spectrum and a time-dependent (nonfactorizable) speckle structure. The gain increments μ ( p ) and the corresponding specklon solution for a Stokes wave are found in the case of an arbitrary ratio of the widths of the pump line Δω l , and of the stimulated scattering line Γ. These solutions correspond to partial wavefront reversal, i.e., to reversal of the spectral band of the pump radiation within an interval of width of the order of Γ/2 around a certain frequency p . A comparison of the specklon gain increments with the increments for uncorrelated waves makes it possible to determine the conditions for wavefront reversal.

A new method developed by the authors for the analysis of stimulated scattering of spatially noncoherent radiation is used in a comparative study of the concurrent and opposed interactions of a Stokes field with pump radiation. If there is no correlation between the Stokes and pump waves, the interaction is independent of the relative direction of propagation of the waves. However, if the Stokes and pump waves are correlated, the interaction efficiency depends strongly on the relative directions of the waves. Exact expressions are obtained for the structure of the wave fields and gain increments in the backscattering case and approximate expressions are obtained for the forward scattering. The physical reason for the asymmetry in the amplification is the reproduction by the Stokes signal spectrum of the pump spectrum in the forward scattering case and inversion of this spectrum in the backscattering case. The same reason accounts for a deterioration of the quality of wavefront reversal in the backscattering case compared with the forward scattering.