Ytterbium-doped Ca_4GdO(BO_3)_3: an efficient infrared laser and self-frequency doubling crystal

TLDR

Ytterbium‑doped materials are being explored as neodymium substitutes for infrared lasers, and prior work on Nd‑doped Ca₄GdO(BO₃)₃ showing self‑frequency doubling suggests Yb:GdCOB could also provide efficient visible emission due to negligible second‑harmonic reabsorption. The study aims to investigate the spectroscopic and laser properties of the newly synthesized Yb‑doped Ca₄GdO(BO₃)₃ crystal. Spectroscopic measurements and laser experiments were performed on Yb:GdCOB to assess its performance under Ti:sapphire pumping. Yb:GdCOB achieved a 58.8 % slope efficiency (40 mW threshold) with a 1 % output cou.

Abstract

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 Ca4GdO(BO3)3 (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 Ca4GdO(BO3)3 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.