2-Step Pumped Ylftm Blue Up-Conversion Laser

Several fluoride and oxide Tm and (Tm, Yb) doped crystals such as YLF, GLF, YAG, and YAlO3 were tested for pulsed lasing at the 1D2 -- \u3e F-3(4) transition (453 nm blue) at room temperature under two step pumping by a Ti:sapphire and a dye laser. Laser operation was obtained for the fluoride crystals. The input-output curves exhibit a saturation effect of emission with respect to both pump lasers. This can be explained by a depletion of the H-3(6) ground state of Tm3+ and the competition between the excited state absorption from the H-3(4) intermediate level and the mechanisms depopulating this level