Watt-level 2150 nm fiber laser

We report on two architectures for obtaining watt-level single mode output from a fiber laser at 2150 nm, one based on a diode-pumped Thulium fiber laser, and another based on a Thulium fiber laser pumped Holmium fiber laser. We observe temporal instability in the diode-pumped Tm-doped fiber system when operating at 2150 nm, with unstable pulsing, and a maximum power of 0.935 W. The Ho-doped fiber system pumped by Tm laser operating at the same 2150 nm wavelength shows periodic pulsing at a fixed rate of 21.25 MHz. Pulsing was observed as soon as the laser threshold was reached. Both laser systems operated in a single spatial mode.