Spectroscopic investigation of dysprosium doped BaF2 single crystals pertaining to the 3 μm mid-IR laser potential

We present the results of a comprehensive spectroscopic investigation pertaining to laser potential evaluation of the 3-micron Dy3+ mid-IR transition in the low-maximum phonon energy host barium fluoride (BaF2). This investigation involved absorption, fluorescence, and decay time measurements, recorded for a range of temperatures. Laser-relevant parameters such as absorption and stimulated-emission cross sections, quantum-efficiencies, and radiative lifetimes were determined for room temperature (300 K) and liquid nitrogen temperature. The peak stimulated emission cross section was found to be 0.45x10-20 cm2 at room temperature and 1.58x10-20 cm2 at 77 K. The gain cross sections, predictive of laser potential, were also derived. Finally, an examination of the nature of the non-radiative decay rates as a function of temperature was performed, showing the degree to which multi-phonon relaxation and other non-radiative pathways affect the overall fluorescence behavior.