Diode-pumped laser action at 1.34 μm from the Nd3+:Ca3Ga2Ge3O12 garnet crystal:: Influence of Nd3+ multicenter distribution

Diode-pumped laser action at 1.34 mum from the Nd3+:Ca3Ga2Ge3O12 system is demonstrated and the physical parameters of relevance in laser dynamics reported. The pump-to-infrared conversion efficiency has been investigated as a function of both Nd3+ concentration and output mirror transmittance. From the analysis of laser curves it has been demonstrated that the low laser efficiencies arise from the inhomogeneous line broadening of emission bands induced by multicenter distribution. This analysis has also been employed to determine the ratio between inhomogeneous and homogeneous line broadening (Deltanu(inh)/Deltanu(h) approximate to 2.5), the result being in good agreement with that obtained from spectroscopy. Other mechanisms that could affect the extraction efficiency, such as excited-state absorption and energy-transfer upconversion, have also been evaluated, the results indicating that their influence in laser dynamics is negligible. Finally, we also report on the influence of multicenter distribution on the spectral shape of the 1.34-mum output laser radiation. (C) 2003 Optical Society of America.