Spectroscopic investigations of the 4f5d energy levels of Pr3+ in fluoride crystals by excited-state absorption and two-step excitation measurements

Excited-state absorption spectra obtained by a pulsed pump-probe technique specially designed for the near-UV spectral domain were recorded in three Pr3+-doped fluoride crystals (KY3F10, LiYF4, and BaY2F8). These excited-state absorption spectra correspond to optical transitions from the P-3(0) or the D-1(2) metastable levels of the 4f(2) configuration up to the first energy levels of the 4f5d electronic configuration. The position, the anisotropic behavior, and the line shape of the observed excited-state absorption bands are discussed and compared with ground-state absorption (from level H-3(4)) or direct excitation spectra available in the literature. Subsequently, two-step excitation into the 4f5d high-lying energy levels of Pr-3 by means of P-3(0) and D-1(2) is shown to be an efficient way to produce broadband UV fluorescence by use of pump beams in the blue and the near UV. (C) 1999 Optical Society of America [S0740-3224(99)00712-2].