The surge of interest in ytterbium-doped materials has led to their being proposed as substitutes for their widely used neodymium counterparts for infrared laser emission. Spectroscopic and laser investigations of ytterbium-doped Ca<sub>4</sub>GdO(BO<sub>3</sub>)<sub>3</sub> (Yb:GdCOB), a new ytterbium-doped crystal, are reported. Laser performances under titanium:sapphire pumping suggest that this material is suitable for schemes that include laser-diode pumping. A maximum slope efficiency of 58.8% with a corresponding laser threshold of 40 mW has been demonstrated with a 1% output coupler. Laser oscillations were also observed for output-coupler transmissions of as much as 10%. Self-frequency doubling of infrared-laser emission has been observed for the first time to our knowledge in an ytterbium-doped medium. The recent demonstration of the interesting self-frequency-doubling properties of neodymium-doped Ca<sub>4</sub>GdO(BO<sub>3</sub>)<sub>3</sub> suggests that Yb:GdCOB could also be efficient in visible laser emission because of its lack of reabsorption at the second-harmonic wavelength. All these results show that the calcium oxoborate family can be useful compact and efficient laser-diode-pumped visible-laser sources.
© 1999 Optical Society of America
F. Mougel, K. Dardenne, G. Aka, A. Kahn-Harari, and D. Vivien, "Ytterbium-doped Ca4GdO(BO3)3: an efficient infrared laser and self-frequency doubling crystal," J. Opt. Soc. Am. B 16, 164-172 (1999)