Electric-dipole Transitions Of Rare Earth Ions Research Articles

Influence of excited configurations on the intensities of electric-dipole transitions of rare-earth ions

The theory of induced electric-dipole transitions of rare-earth ions in crystals and glasses is improved by taking into account the third-order effects of perturbation theory with respect to the energies of virtual excitations of 4f electrons to the 5d states. Since the energy regions of excited 4f N − 15d states are usually superimposed with the charge-transfer bands, the effects caused by a virtual transfer of an electron from the outer shells of ions of the surroundings (ligands) to the unfilled 4f N shells are also considered. The Pr3+, Sm3+, and Eu3+ ions are considered as examples. It is found that some difficulties inherent in the Judd-Ofelt calculation scheme are successfully overcome. The agreement of the calculated results with the experimental data improves.

Absorption Spectrum and Optical Parameters of Nd-Doped Barium Sodium Niobate Crystals

Nd-doped barium sodium niobate, (Ba2Na)1-xNdxNb5O15 (Nd:BNN), crystallizes with x=0.025 in a tetragonal system with a filled tungsten bronze structure and the point group 4 mm, conforming to the space group P4bm and z=2. The Curie temperature was 537±2°C. The lattice constants were a=b=1.2446(1) and c=0.3991(1) nm at room temperature. The measured absorption of Nd:BNN was compared to the Judd-Ofelt (JO) theory. When applied, the JO theory of parity-forbidden electric-dipole transitions of rare-earth ions on non-centrosymmetric sites demonstrates good agreement. An absorption band around 808 nm to match laser diode pumping is about three times broader than that of Nd-doped yttrium aluminum garnet crystal. The three intensity parameters Ωt were fitted as 5.677×10-20, 2.231×10-20, and 4.106×10-20 cm2 at t=2, 4 and 6, respectively. The fluorescence branch ratio at 1060 nm is 52.38%. The largest integrated emission cross section ∑(4F3/2→4I11/2) is 10.36×10-18 cm. These results indicate the crystal's potential applications as a practical laser material.