New mid-IR laser based on an erbium activated low phonon energy crystal

Summary form only given. Important DOD applications require high brightness sources in the thermal band from 4.5 /spl mu/m-5.0 /spl mu/m. To fill this need, we have explored direct emission on the 41/sub 9/2/ /spl rarr/ 41/sub 11/2/ transition in trivalent erbium. To avoid multi-phonon quenching of the mid-IR transition, we have investigated chloride host crystals that possess low energy phonon spectra. A simple end-pumped resonator was utilized for these experiments.