Abstract
Quenching of the fluorescence from the 4F3/2 state (upper state of 1.06‐μm laser transition) of YAG : Nd by multiphonon relaxation is investigated. Measurements of the temperature dependence of fluorescence lifetime and relative fluorescence efficiency are compared with an established model for multiphonon processes. An upper limit of 0.2 and a most probable value of 0.02 are obtained for the room‐temperature efficiency of this quenching process.