| 1. |
- Knall, Jennifer, et al.
(author)
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Experimental comparison of silica fibers for laser cooling
- 2020
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In: Optics Letters. - 0146-9592 .- 1539-4794. ; 45:14, s. 4020-4023
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Journal article (peer-reviewed)abstract
- Laser cooling in silica has recently been demonstrated, but there is still a lack of understanding on how fiber composition, core size, and OH- 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 mK 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 OW 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 OH-.
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| 2. |
- Knall, Jennifer, et al.
(author)
-
Laser cooling in a silica optical fiber at atmospheric pressure
- 2020
-
In: Optics Letters. - 0146-9592 .- 1539-4794. ; 45:5, s. 1092-1095
-
Journal article (peer-reviewed)abstract
- For the first time, to the best of our knowledge, laser cooling is reported in a silica optical fiber. The fiber has a 21-μm diameter core doped with 2.06 wt.% YbM3+ and co-doped with Al2O3 and F- to increase the critical quenching concentration by a factor of 16 over the largest reported values for the Yb-doped silica. Using a custom slow-light fiber Bragg grating sensor, temperature changes up to -50 mK were measured with 0.33 W/m of absorbed pump power per unit length at 1040 nm. The measured dependencies of the temperature change on the pump power and the pump wavelength are in excellent agreement with predictions from an existing model, and they reflect the fiber's groundbreaking quality for the radiation-balanced fiber lasers.
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