Wide bandwidth Ho:YLF multi-pass amplifier pumped by Tm: fiber laser

We report on a Ho:YLF multipass amplifier resonantly pumped by a Tm:fiber laser and seeded by a low power Tm-Ho:YLF tunable laser, which generates a maximum output power of 3.5 W at 2064 nm and has a gain bandwidth of 22 nm. Remarkable features of YLF are the reduced thermal lensing and good thermo-mechanical behavior, which make it suitable for operation under strong pumping, and the low phonon energy.