Wavelength-locked continuous-wave and Q-switched Ho:CaF laser at 2100.5 nm.

In this paper, we demonstrated a linewidth-narrowed continuous-wave (CW) and acousto-optical Q-switched Ho:CaF laser for the first time. With a volume Bragg grating, a maximum CW output power of 6.94 W at 2100.5 nm, and slope efficiency of 57.9%, an FWHM linewidth of 0.31 nm was obtained. When absorbed pump power was 13.2 W, the maximum average output powers of 6.08 W, 5.9 W, and 5.71 W were achieved in a Q-switched Ho:CaF laser under pulse repetition frequencies of 10 kHz, 5 kHz, and 3 kHz, corresponding to the slope efficiencies of 51.2%, 49.6%, and 48.5%, respectively. The minimum pulse width of 54 ns was achieved at pulse repetition frequency of 3 kHz.