Laser cooling of Yb³⁺-doped LuLiF₄ 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. % ${\mathrm{Yb}}^{3+}$-doped ${\mathrm{LuLiF}}_4$ 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 $14.3\mathrm{K}/\mathrm{W}$ are obtained with 79% of the incident laser power being absorbed. Based on our results, a sample with background absorption of $\alpha =4.2\times {10}^{-4}{\mathrm{cm}}^{-1}$ can be potentially cooled down to $\sim 145\mathrm{K}$. Our investigation shows that ${\mathrm{Yb}}^{3+}$-doped ${\mathrm{LuLiF}}_4$ crystal is potentially a promising candidate for solid-state refrigeration.

© 2014 Optical Society of America