Laser time-resolved selective excitation of Nd3+ ions in KNdP4O12 crystals

The emission spectra of Nd³⁺ ions in KNd_xRE_1?xP₄O₁₂ (RE = Y, La and Pr) and KNd_xCr_1?xP₄O₁₂ crystals were investigated. Under selective excitation into ²G$\text{7}\text{2}$ + ⁴G$\text{5}\text{2}$ multiples at 1.6 K the fluorescence of Nd³⁺ ions in non-equivalent crystal sites was observed. The excitation spectrum of the ${}^4\text{F}\text{3}\text{2}$ fluorescence had a complex satellite structure. Time resolved measurements showed the dependence of the fluorescence decay on the excitation wavelength. Selective excitation into the satellite lines at the wings of the main transition led to strongly non-exponential decay. The low temperature results indicated that there is no spectral energy transfer between ions in different types of sites.