Superquadratic behavior of upconversion luminescence transients in rare-earth-ion doped laser crystals

Abstract

Inhomogeneous active-ion distributions in laser materials lead to strong deviations of upconversion versus direct luminescence transients from the quadratic law of energy-transfer upconversion. Measured luminescence decay curves in LaSc3(BO3)4:Nd3+ and GdVO4:Nd3+ confirm experimentally the predicted deviations. Differences in energy migration within the metastable level of Nd3+ are identified