Abstract

A refractive-index matched experimental setup that largely eliminates the effect of radiation trapping on measured excited-state lifetimes in high refractive index solids is presented. An index-matched glass sphere was used to measure the room-temperature lifetimes of ²F_5/2 in YAG:l%Yb³⁺ and ⁴I_11/2 in YLF:5%Er³⁺, yielding the record low values of 948.9±0.6 μs and 3.85±0.01 ms, respectively. It is concluded that lifetimes from non index-matched experiments are most likely to be significantly overestimated in high refractive-index solids for excited states with a large radiative component to the ground-state multiplet and a high reabsorption cross section. The presented technique is easily applicable to room-temperature excited-state lifetime measurements of many luminescent solids.

© 1996 Optical Society of America