Room-temperature E parallel to b and E perpendicular to b polarized ex
cited-state absorption (ESA) measurements on Mn6+-doped crystals of Ba
SO4 in the 530-1800-nm spectral region are reported. ESA transitions f
rom the metastable T-2(2) ligand-field state to the lowest-energy liga
nd-to-metal charge transfer states involve two-electron excitations an
d thus carry low intensity. A strong ESA band owing to the first one-e
lectron 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 stimul
ated-emission cross section is larger than the ESA cross section over
the whole range of spontaneous emission. Our results indicate that tun
able laser action between 920 nm and 1.6 mu m should, in principle, be
achievable. The effective peak stimulated-emission cross section at 1
100 nm is 3 x 10(-19) cm(2). (C) 1997 Optical Society of America.