Modeling visible and infrared stimulated emission from Tb3+ in TbAlO3

With recently developed diode-lasers to resonantly pump solid-state crystalline lasers, new opportunities arise for systems such as Tb3+ as an activator ion in different host matrices. For example the observed fluorescence from 5D4→ 7F5 transition (540 to 560 nm) of Tb3+ in TbAlO3 represents such a possibility. There is little fluorescence quenching in this crystal involving this transition, and the measured lifetime is approximately 2 ms, long enough to sustain sufficient population for stimulated emission. The quantum efficiency is better than 50 % as measured in this material. For this same transition, others have reported room-temperature pulsed laser operation at 544 nm for Tb:YLF, where the lifetime is comparable. Mid- and long wavelength infrared laser emission has been observed for Tb3+ in chalcogenide glass fibers that complement our spectroscopic findings for Tb3+ in pedestal-grown Y2O3 and YAG fibers. We have identified the infrared transitions that may lase at transitions between different manifolds within the 7FJ multiplet. In the present study we first evaluate the various visible and infrared experimental findings with a Judd-Ofelt analysis of Tb3+ in TbAlO3. We predict a radiative lifetime of 3.5 ms for the excited 5D4 manifold to the 7FJ manifolds with more than 50% of the emission represented by the 5D4→ 7F5 transition. To account for the visible stimulated emission, we report transition probabilities for 5D4→ 7FJ transitions and for diode-pumped infrared transitions we report similar spectroscopic properties for transitions within the 7FJ multiplet.