HIGH-EFFICIENCY LASING AT 810 NM IN SINGLE-MODE TM3+ DOPED FLUOROZIRCONATE FIBER PUMPED AT 778 NM

We report a Tm3+ doped fluorozirconate fiber laser suitable for the fi rst telecommunications window. We present a mathematical model and exp erimental measurements. The cw, low threshold pump power of 15 mW, pum ped by a Ti:sapphire laser at 778 nm, and a 85 mW maximum output power around 810 nm with a 85% slope efficiency against launched pump power are achieved. This represents a conversion efficiency of similar to 9 5%, which is the highest reported to date for any laser. Visible up-co nversion fluorescence is also observed. We describe two different osci llator configurations. (C) 1998 Society of Photo-Optical Instrumentati on Engineers. [S0091-3286(98)00610-2].