Optically induced shifts in the frequency of the 3H4-1D2 transition of Pr3+ in LaF3.

Photon-echo techniques were employed to measure the homogeneous dephasing rate of the 592.5-nm, $^{3}$${\mathit{H}}_{4\mathrm{\ensuremath{-}}}^{1}$${\mathit{D}}_{2}$, transition of ${\mathrm{Pr}}^{3+}$ as experimental parameters affecting the number of ${\mathrm{Pr}}^{3+}$ ions optically excited were varied. These parameters include the dopant concentration and the intensity, carrier frequency, and bandwidth of the excitation pulses. Dephasing rates are found to contain a background contribution whose magnitude is dependent upon the specific crystal sample studied and a second contribution whose magnitude increases with the number of ${\mathrm{Pr}}^{3+}$ ions changing state in the course of the echo excitation sequence. The second contribution to the dephasing rate is attributed to the presence of optical instantaneous diffusion, i.e., the redistribution of ionic transition frequencies consequent to optical excitation, in the samples.