We report the first observation of cw lasing at 2.78 μm in an erbium doped fluorozirconate (ZBLAN) single-mode host fiber, pumped by a laser diode array emitting at 792 nm. An erbium doped fluorozirconate single-mode cw fiber laser at 2.71 μm pumped a tunable argon laser at 476.5 and 501.7 nm was recently reported by Allain et al.1 Brierley and France2 earlier reported a cw laser at 2.7 μm, also pumped by a tunable argon laser, in an erbium doped multimode fiber. Excited state absorption (ESA) of the pump beam by the terminal laser level population was the proposed mechanism for overcoming unfavorable branching ratios and also allowing cw lasing on a normally self-terminating transition.3 In contrast to the argon laser, diode pumping has the advantages of much higher efficiency and compactness.

© 1990 Optical Society of America

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