Temperature-dependent polarization effects in Ce : LiLuF

We report on tuned-laser, pump-probe-gain, and fluorescence Yield studies o f the effect that crystal temperature plays on the polarized emission chara cteristics of Ce:LiLuF. It was found that or-polarized emission at the 327- nm fluorescence spectra peak is characterized by smaller laser pulse buildu p times, higher small-signal gains, and smaller output powers than the Tr-p olarized 327-nm emission. We concluded that excited-state absorption (ESA) (and the resultant formation of color centers) is more severe for cr-polari zed emission than for ir-polarized emission in this spectral region. We pos tulate that the enhancement in laser performance and crystal fluorescence o bserved with crystal cooling is due to narrowing of the ESA absorption band that reduces the probability of ESA and color-center formation. (C) 2001 O ptical Society of America.