Diode-pumped solid-state Nd3+:Ca3Ga2Ge3O12 crystal lasers

Spectral, luminescent and laser parameters of Nd³⁺:Ca₃Ga₂Ge₃O₁₂ (Nd:CGGG) crystals are studied and compared with the corresponding parameters of Nd:YAG crystals. Continuous-wave spatially single-mode lasing in these crystals at a wavelength of 1.064 μm is investigated upon longitudinal diode pumping through an optical fibre and it is shown that the pump geometries being the same, the output power of a Nd:CGGG laser is close to that of a Nd:YAG laser. The effective cross section σ for induced transitions is measured, which is 1.4 × 10^-19 cm² for Nd:CGGG crystals. It is found that the 1.064-μm line of the Nd:CGGG laser is inhomogeneously broadened and has a fine structure of four distinct peaks conforming the spectroscopic data about the existence of four main types of activator Nd³⁺ ions in Ca₃Ga₂Ge₃O₁₂ crystals. The output power of 700 mW for the absorbed pump power of 2.7 W is obtained for a compact cw solid-state laser with the 1-mm thick active element. It is shown that the thermal distortions of the active element are the main mechanisms limiting the output power of a solid-state Nd:CGGG crystal laser.