The effect of pressure on the luminescence of Cr 3+: YAG

Abstract

Pressure can be used to tune the energy separation between electronic levels involved in absorption, emission and energy transfer processes by directly altering ion-ion distances, spectral overlap, and the lattice spacing of a laser host. We report here the use of pressure to tune the optical properties of Cr 3+ in yttrium aluminum garnet. Photoluminescence measurements show an increase in the energy difference between the 4T 2 and 2E levels of Cr 3+ and a decrease in R-line splitting as the pressure is raised. Pulsed luminescence measurements reveal a twelve-fold increase in Cr 3+ R-line lifetime over the pressure range 0–150 kbar. These effects are believed to be consistent with a decrease in the trigonal distortion at the Cr 3+ site in YAG and a reduction of the degree of spin-orbit coupling at high pressure.