Single-transverse-mode 2.5-W holmium-doped fluoride fiber laser operating at 2.86 microm

A high-power tandem-pumped Ho3+, Pr3+-doped ZBLAN fiber laser is demonstrated. Using the free-running 1100-nm output from a diode-cladding-pumped Yb3+-doped silica fiber laser as the pump source, a maximum output power of 2.5 W was generated at a slope efficiency of 29% after the threshold of approximately 30 mW was reached. Saturation of the output is avoided with Pr3+ codoping, which allows single-transition output. The center wavelength of the output was 2.86 microm and the bandwidth at maximum power was approximately 15 nm.