A new evaluation of Yb3+-doped crystals for laser applications

We develop a new model for the quasi-three-level laser. It deals with Gaussian waves, takes into account the saturation of the pump, the stimulated emission at the pump wavelength, the variation of the pump and laser waists along propagation (important for laser diode pumping) and the variation of the laser intensity along propagation. The model is used to evaluate the most promising Yb3+-doped crystals: YAG, GdCOB, YCOB, YAB, C-FAP, S-FAP, KGdW, KYW, for CW longitudinally pumped lasers. Our evaluation differs from Deloach and coworkers, devoted to Q-switched oscillators or nanosecond-pulse amplifiers. KYW, KGdW, YAB and GdCOB are found to be the most efficient when the laser extracted power and the slope efficiency are considered.