Laser cooling of Yb^3+-doped LuLiF_4 crystal

Abstract

In order to meet the demands for applications of optical refrigerators in the fields of spaceflight, aviation, space science, and detection, a 2 wt. % Yb3+-doped LuLiF4 crystal, as a new laser cooling material, was prepared and demonstrated by using a 178 mW diode laser centered at 1015 nm and a resonant extra-cavity scheme with an enhancement factor of 12.8. Cooling efficiency of 1.27% and a temperature drop of 14.3 K/W are obtained with 79% of the incident laser power being absorbed. Based on our results, a sample with background absorption of α=4.2×10(-4) cm(-1) can be potentially cooled down to ∼145 K. Our investigation shows that Yb3+-doped LuLiF4 crystal is potentially a promising candidate for solid-state refrigeration.

Investigation of Yb-doped LiLuF4single crystals for optical cooling

“…Although optical cooling in Yb-doped LLF single crystals has been already demonstrated, 12 in this work, we report on measurements of the intrinsic cooling efficiency curve, with evaluation of external quantum efficiency (EQE) and background absorption parameters. High-quality LLF single crystals-doped Yb at 5 at.% have been grown, optically characterized, and tested in a standard set-up.…”

Cavity-enhanced laser cooling for Yb^3+-doped fluoride crystal using a low-power diode laser

“…However, although the absorption cross section of the Yb 3 :YLiF 4 crystal is larger than that of the Yb 3 :LuLiF 4 crystal with the same Yb 3 -doped level, the cooling efficiency of the former is slightly lower than that (1.27%) of the latter because the background absorption (α b 3.75 × 10 −3 cm −1 ) of the Yb 3 :YLiF 4 crystal is larger than that (α b 2.5 × 10 −3 cm −1 ) of the Yb 3 :LuLiF 4 crystal [17], which results in a larger temperature drop (ΔT 2.0 K) of Yb 3 :LuLiF 4 crystal [17] than that (ΔT 1.8 K) of Yb 3 :YLiF 4 in our experiment. However, with the same level of purity and Yb 3 -doped concentration, the Yb 3 :YLiF 4 crystal will have a larger cooling efficiency than the Yb 3 :LuLiF 4 crystal.…”

Hydrothermal Synthesis and Solid-State Laser Refrigeration of Ytterbium-Doped Potassium Lutetium Fluoride (KLF) Microcrystals

“…This variety of crystal structures provides a rich array of potential host environments for Yb 3+ ions for laser refrigeration. Beyond the diversity of phases, recent work has also explored replacing the common host element yttrium with lutetium, 30 as the lutetium-lithium-fluoride phase diagram exhibits congruent melting. 31 There is also a close match in cation size between Lu 3+ (861 pm) and the dopant ion Yb 3+ (868 pm), 32 which allows better crystal quality.…”