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Title: Diffraction-controlled backscattering threshold and application to Raman gap

Abstract

In most classic analytical models of linear stimulated scatter, light diffraction is omitted, a priori. However, modern laser optic typically includes a variant of the random phase plate [Y. Kato et al., Phys. Rev. Lett. 53, 1057 (1984)], resulting in diffraction limited laser intensity fluctuations - or localized speckles - which may result in explosive reflectivity growth as the average laser intensity approaches a critical value [H. A. Rose and D. F. DuBois, Phys. Rev. Lett. 72, 2883 (1994)]. Among the differences between stimulated Raman scatter (SRS) and stimulated Brillouin scatter is that the SRS scattered light diffracts more strongly than the laser light with increase of electron density. This weakens the tendency of the SRS light to closely follow the most amplified paths, diminishing gain. Let G{sub 0} be the one-dimensional power gain exponent of the stimulated scatter. In this paper we show that differential diffraction gives rise to an increase of G{sub 0} at the SRS physical threshold with increase of electron density up to a drastic disruption of SRS as electron density approaches one fourth of its critical value from below. For three wave interaction lengths not small compared to a speckle length, this is a physicallymore » robust Raman gap mechanism.« less

Authors:
 [1];  [2];  [3]
  1. New Mexico Consortium, Los Alamos, New Mexico 87544 (United States)
  2. (United States)
  3. Centre de Physique Theorique, UMR 7644 du CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France)
Publication Date:
OSTI Identifier:
21537632
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 18; Journal Issue: 4; Other Information: DOI: 10.1063/1.3581083; (c) 2011 American Institute of Physics
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BACKSCATTERING; BRILLOUIN EFFECT; DIFFRACTION; ELECTRON DENSITY; LASERS; RAMAN EFFECT; REFLECTIVITY; COHERENT SCATTERING; OPTICAL PROPERTIES; PHYSICAL PROPERTIES; SCATTERING; SURFACE PROPERTIES

Citation Formats

Rose, Harvey A., Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, and Mounaix, Philippe. Diffraction-controlled backscattering threshold and application to Raman gap. United States: N. p., 2011. Web. doi:10.1063/1.3581083.
Rose, Harvey A., Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, & Mounaix, Philippe. Diffraction-controlled backscattering threshold and application to Raman gap. United States. doi:10.1063/1.3581083.
Rose, Harvey A., Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, and Mounaix, Philippe. Fri . "Diffraction-controlled backscattering threshold and application to Raman gap". United States. doi:10.1063/1.3581083.
@article{osti_21537632,
title = {Diffraction-controlled backscattering threshold and application to Raman gap},
author = {Rose, Harvey A. and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544 and Mounaix, Philippe},
abstractNote = {In most classic analytical models of linear stimulated scatter, light diffraction is omitted, a priori. However, modern laser optic typically includes a variant of the random phase plate [Y. Kato et al., Phys. Rev. Lett. 53, 1057 (1984)], resulting in diffraction limited laser intensity fluctuations - or localized speckles - which may result in explosive reflectivity growth as the average laser intensity approaches a critical value [H. A. Rose and D. F. DuBois, Phys. Rev. Lett. 72, 2883 (1994)]. Among the differences between stimulated Raman scatter (SRS) and stimulated Brillouin scatter is that the SRS scattered light diffracts more strongly than the laser light with increase of electron density. This weakens the tendency of the SRS light to closely follow the most amplified paths, diminishing gain. Let G{sub 0} be the one-dimensional power gain exponent of the stimulated scatter. In this paper we show that differential diffraction gives rise to an increase of G{sub 0} at the SRS physical threshold with increase of electron density up to a drastic disruption of SRS as electron density approaches one fourth of its critical value from below. For three wave interaction lengths not small compared to a speckle length, this is a physically robust Raman gap mechanism.},
doi = {10.1063/1.3581083},
journal = {Physics of Plasmas},
number = 4,
volume = 18,
place = {United States},
year = {Fri Apr 15 00:00:00 EDT 2011},
month = {Fri Apr 15 00:00:00 EDT 2011}
}