Temperature-dependent polarization effects in Ce:LiLuF

We report on tuned-laser, pump--probe-gain, and fluorescence yield studies of the effect that crystal temperature plays on the polarized emission characteristics of Ce:LiLuF. It was found that [Sigma]-polarized emission at the 327-nm fluorescence spectra peak is characterized by smaller laser pulse buildup times, higher small-signal gains, and smaller output powers than the [Pi]-polarized 327-nm emission. We concluded that excited-state absorption (ESA) (and the resultant formation of color centers) is more severe for [Sigma]-polarized emission than for [Pi]-polarized emission in this spectral region. We postulate that the enhancement in laser performance and crystal fluorescence observed with crystal cooling is due to narrowing of the ESA absorption band that reduces the probability of ESA and color-center formation. OCIS codes: 140.0140, 140.3320, 140.3610, 140.3580, 140.6810.