Experimental comparison of silica fibers for laser cooling

Laser cooling in silica has recently been demonstrated, but there is still a lack of understanding on how fiber composition, core size, and O H − contamination influence cooling performance. In this work, six Yb-doped silica fibers were studied to illuminate the influence of these parameters. The be...

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Bibliographic Details
Published in:Optics letters 2020-07, Vol.45 (14), p.4020-4023
Main Authors: Knall, Jennifer, Engholm, Magnus, Ballato, John, Dragic, Peter D., Yu, Nanjie, Digonnet, Michel J. F.
Format: Article
Language:English
Subjects:
Absorptivity
Cooling
Laser cooling
Lasers
Quenching
Silicon dioxide
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Summary:Laser cooling in silica has recently been demonstrated, but there is still a lack of understanding on how fiber composition, core size, and O H − contamination influence cooling performance. In this work, six Yb-doped silica fibers were studied to illuminate the influence of these parameters. The best fiber cooled by − 70 m K with only 170 mW/m of absorbed pump power at 1040 nm, which corresponds to twice as much heat extracted per unit length compared to the first reported laser cooling in silica. This new fiber has an extremely low O H − loss and a higher Al concentration (2.0 wt.% Al), permitting a high Yb concentration (2.52 wt.% Yb) without incurring significant quenching. Strong correlations were found between the absorptive loss responsible for heating and the loss measured at 1380 nm due to absorption by O H − .
ISSN:0146-9592
1539-4794
1539-4794
DOI:10.1364/OL.395513