Physical review. B, Condensed matter
Intensity-dependent photon-echo relaxation in rare-earth-doped crystals
Stefan Kröll, E. Y. Xu, M. K. Kim, Masaharu Mitsunaga, Ravinder Kachru
Abstract
Photon-echo-relaxation measurements made on the $^{3}\mathrm{H}_{4}$${\mathrm{\ensuremath{-}}}^{3}$${\mathrm{P}}_{0}$ transition of 0.01 at. % ${\mathrm{Pr}}^{3+}$:YAG (where YAG represents yttrium aluminum garnet), $^{3}\mathrm{H}_{4}$${\mathrm{\ensuremath{-}}}^{1}$${\mathrm{D}}_{2}$ transition in 0.1 at. % ${\mathrm{Pr}}^{3+}$:${\mathrm{YAlO}}_{3}$, and $^{7}\mathrm{F}_{0}$${\mathrm{\ensuremath{-}}}^{5}$${\mathrm{D}}_{0}$ transition in 0.25 at. % ${\mathrm{Eu}}^{3+}$:${\mathrm{YAlO}}_{3}$ show that the photon-echo relaxation rate increases when the intensities of the excitation pulses are increased. Although a part of the relaxation-rate increase in ${\mathrm{Pr}}^{3+}$:YAG may be attributed to an instantaneous spectral diffusion (ISD) in which the presence of excited neighboring ${\mathrm{Pr}}^{3+}$ ions change the local field and the absorption frequency of the rare-earth ions, our data deviate significantly from the ISD-model predictions. An additional intensity-dependent relaxation mechanism is required to explain the results.