Numerical modeling of multi-point side-pumped mid-infrared erbium-doped fluoride fiber lasers.

We investigate the power scaling and thermal management of multi-point side-pumped 2.825 µm heavily-erbium-doped fluoride fiber lasers by numerical simulation. The 4-point (or 6-point) erbium-doped fluoride fiber laser with polished erbium-doped fluoride fiber-based side-pump couplers delivers an output laser power of over 100 W at each launched 981 nm pump power of 100 W (or 75 W). Meanwhile, the core temperature increases of the gain fiber tips are below 1 K, making it possible for a highly reflective fiber Bragg grating to work stably in high-power operation. Once the preparation processes of these erbium-doped fluoride fiber-based side-pump couplers and endcaps with effective coatings are mature, the proposed multi-point side-pumped erbium-doped fluoride fiber lasers with some feasibility may theoretically pave the way for the development of hundred-watt mid-infrared fiber lasers with effective thermal management.