Increasing the SBS threshold in single-mode step-index optical fiber by design of highly multimode acoustic profile

Sergey V. Tsvetkov, Maxim M. Khudyakov, Alexey S. Lobanov, Denis S. Lipatov, Michael M. Bubnov, Valery Temyanko, Michael E. Likhachev

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


The stimulated Brillouin scattering (SBS) is the main power limiting factor in the high-power narrow-line fiber laser circuits. A good way to increase the SBS power-threshold is to reduce its coherent gain, which is directly connected with the width of the Brillouin gain spectrum (BGS). The Brillouin gain peak and the phonons life-time are inversely proportional to the full-width-at-half-maximum of the BGS. The fine structure of the BGS and its ranges are sufficiently affected by parameters of the acoustic waveguide of the fiber. We propose a novel approach for increasing the BGS width and lowering its maximum (related directly to the SBS threshold) for a given optical refractive index profile. The aim of the approach is to maximize both the number and spectral spread of guided acoustic modes, as well as equate the acousto-optic interaction coefficients (acousto-optical overlap integrals) for the maximum possible number of these modes. This is due to the fact that an increase in the number of acoustic modes effectively contributing to the BGS, while preserving the distribution of the optical mode intensity, causes the scattered Stokes optical power to be redistributed accordingly between the corresponding number of Brillouin spectral lines, providing proportional damping of the Brillouin gain. Such an acoustically multimode SBS suppression can be achieved by tailoring a proper radial acoustic refractive index profile which can be fabricated by co-doping of silica with phosphorous oxide and fluorine.

Original languageEnglish (US)
Title of host publicationFiber Lasers XVIII
Subtitle of host publicationTechnology and Systems
EditorsMichalis N. Zervas, Cesar Jauregui-Misas
ISBN (Electronic)9781510641655
StatePublished - 2021
EventFiber Lasers XVIII: Technology and Systems 2021 - Virtual, Online, United States
Duration: Mar 6 2021Mar 11 2021

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceFiber Lasers XVIII: Technology and Systems 2021
Country/TerritoryUnited States
CityVirtual, Online


  • Acoustic index profile
  • Brillouin gain spectrum
  • Fiber acoustic modes
  • SBS gain suppression
  • Single-mode optical fibers
  • Stimulated Brillouin scattering

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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