Energy recycling versus lifetime quenching in erbium-doped 3-/spl mu/m fiber lasers

Summary form only given. In recent years, there have been enormous research efforts to improve the performance of lasers emitting at 3 /spl mu/m mainly because of their potential applications in laser surgery. Due to the high absorption of 3-/spl mu/m radiation in water, high-quality cutting or ablation is demonstrated in biological tissue using erbium-doped solid-state lasers. We have recently demonstrated a CW output power of 17 W at 2.7 /spl mu/m with a slope efficiency of 17% from an Er/sup 3+/,Pr/sup 3+/ codoped ZBLAN fiber. In this paper, we investigate whether energy recycling by energy-transfer upconversion (ETU) from the lower laser level with its inherent enhancement of the slope efficiency by a factor of 2 can operate this fiber laser more efficiently than lifetime quenching of the lower laser level by the Pr/sup 3+/ codopant.