Fiber amplifiers under thermal loads leading to transverse mode instability

Mette Marie Johansen, Kristian Rymann Hansen, Thomas Tanggaard Alkeskjold, Jesper Lægsgaard

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


Transverse mode instability (TMI) in rare-earth doped fiber amplifiers operating above an average power threshold is caused by intermodal stimulated thermal Rayleigh scattering due to quantum defect heating. We investigate thermally induced longitudinal waveguide perturbations causing power transfer from the fundamental mode (FM) to the higher order mode (HOM) by a nonlinear gain, which depends on the FM-HOM frequency shift and position along the fiber. We take temperature and mode profile evolution along the fiber into consideration to engineer fiber designs with increased TMI threshold and operation stability at higher average powers.
Original languageEnglish
Title of host publicationFiber Lasers XI: Technology, Systems, and Applications
Number of pages9
PublisherSPIE - International Society for Optical Engineering
Publication date2014
Article number89612P
Publication statusPublished - 2014
EventFiber Lasers XI : Technology, Systems, and Applications - The Moscone Center, San Francisco, California, United States
Duration: 7 Feb 201412 Feb 2014


ConferenceFiber Lasers XI
LocationThe Moscone Center
CountryUnited States
CitySan Francisco, California
SeriesProceedings of SPIE, the International Society for Optical Engineering


  • Fiber amplifiers
  • transverse mode instability
  • microstructured fibers
  • high power amplifiers
  • thermal effects

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