Watt-level, mid-infrared output from a BaWO(4) external-cavity Raman laser at 2.6  μm

An external-cavity Raman laser with a BaWO(4) crystal is reported to generate a high-brightness, mid-infrared output at 2.6 μm. An actively Q-switched Ho:YAG laser at 2.097 μm is used as the pump source. The first Stokes output from the Raman laser reached 1.35 W with a near-diffraction-limited beam quality. Pulse widths as short as 8.5 ns are measured at a repetition rate of 5 kHz. Maximum conversion efficiency with respect to the incident pump power is measured as 14%. This simplified external-cavity configuration facilitates the realization of Raman-shifted sources within the water absorption window, using fixed and tunable Tm- and Ho-doped solid-state and fiber lasers.