This normalization gives the cooling efficiency, defined as the ratio of the cooling power to the absorbed laser power. In agreement with Eq. Experimentally, the zero crossing agrees with this prediction to within 3 nm, indicating that the radiative quantum efficiency is at least 0.997. The deviations from linearity for 1020 nm may be explainable in terms of parasitic heating in our sample or experimental artifacts. The experimental cooling efficiency in Fig.
Negative efficiencies correspond to heating.
The amplitudes of the two data curves have been adjusted using the scaling factors from Figs. USSR - Phys. Cooling of gases by laser radiation, Opt. A.V. Olinto, W.C. Priedhorsky, W.R. Scarlett, and P. Xie for helpful discussions and comments. A.J. Gibbs and J. Fajardo are appreciated for help in preparing the glass samples.