Abstract

The nanosecond and microsecond fluorescence kinetics decay from ³F₃, ³H_4, 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.

© 1996 Optical Society of America