Two Kinds of Cavity Geometry for Enhanced Laser Cooling of Solids

We present a comparison between intracavity cooling and external cavity cooling for optical refrigeration. The results show that the intracavity scheme is preferred at low optical densities (<0.008), while the external cavity scheme is preferred at higher optical densities (>0.01). We can choose the proper scheme for different cases in experiments. Moreover, under the same conditions, taking Yb³⁺-doped ZBLAN (ZrF₄-BaF₂-LaF₃-AlF₃-NaF) film as an example, the cooling processes of the two scheme are obtained. The calculated results show that intracavity cooling will achieve a larger temperature drop for a thin film sample. Finally, the diode laser may become a candidate for the intracavity model briefly discussed.