Excited-state absorption and laser potential of Mn6+-doped BaSO4 crystals

Room-temperature E parallel to b and E perpendicular to b polarized excited-state absorption (ESA) measurements on Mn6+-doped crystals of BaSO4 in the 530-1800-nm spectral region are reported. ESA transitions from the metastable T-2(2) ligand-field state to the lowest-energy ligand-to-metal charge transfer states involve two-electron excitations and thus carry low intensity. A strong ESA band owing to the first one-electron ligand-to-metal charge transfer transition peaks near 600 nm. Between 700 and 900 nm, ground-state absorption is stronger than ESA, and near-infrared pumping by laser diodes is thus possible. The stimulated-emission cross section is larger than the ESA cross section over the whole range of spontaneous emission. Our results indicate that tunable laser action between 920 nm and 1.6 mu m should, in principle, be achievable. The effective peak stimulated-emission cross section at 1100 nm is 3 x 10(-19) cm(2). (C) 1997 Optical Society of America.