Quantum efficiency measurements in Yb-doped crystals using an optical method

The quantum efficiency, defined as the ratio of excited ions that decay radiatively (under nonlasing conditions), is an important parameter for laser efficiency. concentration quenching (and to a lesser extent multiphonon nonradiative decay) is likely to take place in Yb-doped materials, and reduces the quantum efficiency in highly-doped crystals that are commonly used under diode pumping. In this paper we relate quantum efficiency measurements in Ytterbium-doped YAG, GGG, KGW, YSO, GdCOB and YCOB, performed with a thermal lensing measurement technique, developed for diode-end-pumping configurations.