Abstract :
A rate-equation analysis of the erbium 3-μm ZBLAN fiber laser is performed. The computer calculation includes the longitudinal spatial resolution of the host material. It considers ground-state bleaching, excited-state absorption (ESA), interionic processes, lifetime quenching by co-doping, and stimulated emission at 2.7 μm and 850 mn. State-of-the-art technology including double-clad diode pumping is assumed in the calculation. Pump ESA is identified as the major problem of this laser. With high Er3+ concentration, suitable Pr3+ co-doping, and low pump density, ESA is avoided and a diode-pumped erbium 3-μm ZBLAN laser is predicted which is capable of emitting a transversely single-mode output power of 1.0 W when pumped with 7-W incident power at 800 nm. The corresponding output intensity which is relevant for surgical applications will be in the range of 1.8 MW/cm2. Compared to Ti:sapphire-pumped cascade-lasing regimes, the proposed approach represents a strong decrease of the requirements on mirror coatings, cavity alignment, and especially pump intensity. Of the possible drawbacks investigated in the simulation, only insufficient lifetime quenching is found to have a significant influence on laser performance
Keywords :
aluminium compounds; barium compounds; erbium; excited states; fibre lasers; infrared sources; lanthanum compounds; laser cavity resonators; laser mirrors; laser transitions; optical films; optical pumping; optical saturable absorption; sodium compounds; stimulated emission; zirconium compounds; 1 W; 2.7 mum; 3 mum; 7 W; 850 nm; Er-doped ZBLAN fiber laser; Pr3+ co-doping; ZBLAN:Er; ZrF4-BaF2-LaF3-AlF3-NaF:Er; cavity alignment; computer calculation; corresponding output intensity; diode-pumped Er-doped 3-μm fiber laser; double-clad diode pumping; excited-state absorption; ground-state bleaching; high Er3+ concentration; host material; incident power; interionic processes; lifetime quenching; longitudinal spatial resolution; low pump density; mirror coatings; pump ESA; pump intensity; rate-equation analysis; stimulated emission; transversely single-mode output power; Absorption; Bleaching; Diodes; Erbium; Erbium-doped fiber lasers; Laser excitation; Optical materials; Performance analysis; Pump lasers; Spatial resolution;
