A power scaled diode cladding pumped 2.8 µm Er:ZBLAN fiber laser (Conference Presentation)

Recent progress in development of Mid–IR lasers at ~2.8 µm and ~3.5 µm based on commercial Er:ZBLAN fibers has enabled variety of environmental sensing, defense and medical applications. This development faces a few major challenges, among which are relatively low laser efficiency (stemming from the naturally high quantum defect of laser operation) and power scaling limitation due to output self-pulsing (perceived to be coming from presence of clustering or ion pairs in a highly doped fiber, which act as saturable absorbers).We report on a study of the power scaling of a 976 nm diode-pumped double-clad Er:ZBLAN fiber laser at the ~2.8 µm, 4I11/2-4I13/2 transition. The passively cooled 7% Er-doped fluoride fiber laser was shown to achieve slope efficiency over 25% and 50 W with respect to launched pump power in both CW and Quasi-CW regimes of free-running operation. Laser power scaling was found to be limited by available 976 nm diode pump power.