Optical gain and loss studies in Ce^3+:YLiF_4

Transient and stable color centers created by optical pumping at 308 nm have been studied in Ce3+:YLiF4. Since the color centers are absorptive at the cerium emission wavelengths, they degrade the Ce3+:YLiF4 laser performance. The color centers are produced following a multiphoton ionization of the Ce3+ ions. Rate equations that incorporate both creation and photobleaching processes are developed to model the observed kinetics and intensity dependence of the color-center density. Measurements of the single-pass gain at 325 nm as a function of the repetition rate of the pump laser are interpreted in terms of the relaxation time of the transient centers.