Photon-echo attenuation by dynamical processes in rare-earth-ion-doped crystals

We study the photon-echo attenuation by various dynamical processes in rare-earth-ion-doped crystals. The experimental investigations concentrate on a Pr3+:EU3+:Nd3+ codoped Y2SiO5 crystal at low temperatures. Two-pulse photon-echo intensities are measured as a function of the pulse intensities when either the Pr3+ Or the EU3+ ions are excited. For the quantitative interpretation we consider primarily excitation-induced frequency shifts (EFS) by diagonal and off-diagonal interactions and show that for the systems under consideration EFS are dominated by diagonal interactions. The observed echo attenuation by EFS is compared with the predictions calculated from independent Stark-field measurements and reasonable agreement is obtained. The broadening by spin-ion interactions, by nonequilibrium phonons and the dependence of the echo attenuation on the frequency position in the inhomogeneously broadened band are further investigated.