Oxysulfide optical ceramics doped by Nd 3+ for one micron lasing

Effect of B2O3 addition on luminescent properties and energy transfer in Er3+/Ho3+-codoped tellurite glasses

Intensity of the 2.9μm fluorescence from Dy3+ in Ge25Ga5S70 glass increased with increasing Tm3+ content when the Dy3+ concentration remained constant, which indicates the presence of an efficient energy transfer between Tm3+ and Dy3+. Analyses of the emission intensities and decay times suggested that a direct energy transfer from the Tm3+:3F4 level to Dy3+:6H11/2 level occurred after a fast diffusion-limited migration of the excitation energy among Tm3+. A decrease in the measured lifetimes of the Tm3+:3F4 level and a wide spectral overlap between the Tm3+: 1.8μm emission and the absorption of Dy3+: 6H15/2➝ 6F11/2 also supported the proposed energy transfer scheme. Multiphonon relaxation rates in sulfide glasses were orders of magnitude lower than those for conventional oxide glasses.

Multiphonon relaxation rates measurements and theoretical calculations in the frame of non-linear and non-Coulomb model of a rare-earth ion-ligand interaction

Fluorescence quenching of the Nd 3+ ions in different optical centers in fluorite-type crystals

Temperature dependencies of excited states lifetimes and relaxation rates of 3–5 phonon (4–6 μm) transitions in the YAG, LuAG and YLF crystals doped with trivalent holmium, thulium, and erbium

Saturation effect on multiphonon relaxation rates

Alkaline earth fluoride crystals doped with trivalent rare earth contain both isolated and clustered rare earths. Electronic nonradiative relaxation for isolated rare earths proceeds solely by multiphonon relaxation while for clustered rare earths, it proceeds by both efficient nonresonant energy transfer and multiphonon relaxation. We have measured the rates of all the relaxation processes for representative sites in CaF2, SrF2, and BaF2 in order to obtain a comprehensive understanding of relaxation in the materials. Exponential dependences of the multiphonon and energy transfer rates on energy gap have been found. The rates do not appear to scale simply with the lattice phonon energies but depend upon the details of the phonon distribution and coupling. Temperature dependence of the rates indicate a complex mixture of phonons may contribute to the observed relaxation.

The nanosecond and microsecond fluorescence kinetics decay from 3F3, 3H4,3H5, 3F4 multiplets of Tm3+ and 5S2,5F5,5I5,5I6,5I7 multiplets of Ho3+ ions in Y3Al5O12, Lu3Al5O12, and LiYF4 crystals with low dopant concentration was directly measured. On the basis of these measurements the multiphonon relaxation (MPR) rates for three, four, and five phonon transitions were determined.The theoretical depedence of multiphonon relaxation rates versus rare-earth ionic radius was derived using the non-linear (NL) theory of multiphonon relaxation. A good qualitative agreement of this dependence with new and earlier measured MPR rates in rare-earth ions in the row from Tm3+ to Pr3+ in YAG, YLF, and LaF3 crystals was obtained. The regularities of multiphonon relaxation rates on the number of phonons n, 4f-4f electronic transitions selection rules, and crystal type are also considered.

Nd3+-doped fluorozirconate-based glasses which contain hexagonal BaCl2 nanocrystals are analyzed for their photoluminescence and multiphonon relaxation (MPR) properties. The MPR rates of various Nd3+ levels are obtained from time-resolved spectroscopy using selective laser pulse excitation. The nonradiative decay rates are estimated from the difference between measured and calculated radiative decay rates as well as from the analysis of luminescence rise times. The MPR rates display an exponential dependence on the energy gap. Temperature-dependent studies of the decay indicate that phonons of the BaCl2 nanocrystals are involved in the MPR processes leading to extremely low MPR rates which are orders of magnitude lower than in conventional oxide and halide glasses. Photoluminescence emissions, which are usually quenched by MPR, and enhanced radiative quantum efficiencies are found.

The Yb 3+ to Er 3+ energy transfer in YAl 3(BO 3) 4 crystal

Mid-infrared emissions and multiphonon relaxation in Dy 3+-doped chalcohalide glasses

Delayed laser emission from a ND-YAG oscillator pumped by a 532-nm 50-ns pulse is interpreted in terms of multiphonon relaxation from the pumped levels to the upper laser level. The relaxation rate constant, (1.6±0.2)×106 s−1, is in good agreement with previous results obtained from the fluorescence rise time.

Crossrelaxations between and multiphonon relaxation of near-infrared excited states of Pr 3+ ions in selenide glasses

Non-radiative relaxation processes of the Pr 3+ ion in solids

Spectroscopic study of Nd3+/Yb3+ in disordered potassium bismuth molybdate laser crystals