Down- and up-conversion of femtosecond light pulses into Pr3+ luminescence in LiTaO3:Pr3+ single crystal

Spectra and decay curves of luminescence induced in a single crystal of LiTaO3:Pr3+ by femtosecond light pulses at different wavelengths from the UV-Blue and NIR regions were recorded and analyzed. It was found that excited levels involved in the broad UV absorption band of LiTaO3: Pr3+ are not able to relax via radiative transitions but they feed nonradiatively excited states of the ground Pr3+ configuration. Femtosecond pulse excitation in the NIR region results in an up-converted visible luminescence weakly affected by the pulse wavelength within the 1200 nm–1800 nm region. Spectra acquired imply that the supercontinuum (SC) generated does not promote single - or double-photon processes that may feed the 3P0 or 1D2 levels via transitions within the ground 4f2 configuration. It was concluded that the excitation mechanism is consistent with the multiphoton excitation (MPE) that feeds the 5d levels of Pr3+.