Experimental observation of cooling in Yb-doped silica fibers

Jenny M. Knall, Pierre Baptiste Vigneron, Magnus Engholm, Peter D. Dragic, Nanjie Yu, John Ballato, Martin Bernier, Michel Digonnet

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


Anti-Stokes fluorescence cooling in a silica-based fiber is reported for the first time. The fiber had a core with a 20-μm diameter doped with 2.06 wt.% Yb and co-doped with 0.86 wt.% Al and 0.88 wt.% F. Core-pumping the fiber with 1040- nm light, temperature changes as large at -50 mK were measured at atmospheric pressure. Temperature measurements were performed at 12 pump wavelengths, and the measured dependence of the temperature change as a function of pump wavelength was in excellent agreement with a previously reported model. With this model, the absorptive loss in the fiber was inferred to be less than 15 dB/km, and the critical quenching concentration to be ∼15.6 wt.% Yb. This combination of low loss and high quenching concentration (a factor of 16 times higher than the highest reported values for Yb-doped silica) is what allowed the observation of cooling. The temperature measurements were performed at atmospheric pressure using a custom slow-light fiber Bragg grating sensor with an improved thermal contact between the test fiber and the FBG. The improved method involves isopropanol to establish a good thermal contact between the two fibers. This eliminated a source of heating and enabled more accurate measurements of the cooled-fiber temperature. This improved temperaturemeasurement set-up also led to a new cooling record in a multimode Yb-doped ZBLAN fiber at atmospheric pressure. When pumped at 1030 nm, the fiber cooled by -3.5 K, a factor of 5.4 times higher than the previous record.

Original languageEnglish (US)
Title of host publicationPhotonic Heat Engines
Subtitle of host publicationScience and Applications II
EditorsDenis V. Seletskiy, Richard I. Epstein, Mansoor Sheik-Bahae
ISBN (Electronic)9781510633599
StatePublished - 2020
Externally publishedYes
EventPhotonic Heat Engines: Science and Applications II 2020 - San Francisco, United States
Duration: Feb 5 2020Feb 6 2020

Publication series

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


ConferencePhotonic Heat Engines: Science and Applications II 2020
Country/TerritoryUnited States
CitySan Francisco


  • Anti-Stokes fluorescence
  • Laser cooling
  • Optical refrigeration
  • Rare-earth doped fibers
  • Silica fibers

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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