Mid-infrared lightly Er³⁺-doped CaF₂ laser under acousto–optical modulation

A 1.7-at.% Er:CaF₂ crystal was synthesized by temperature gradient method. The Er:CaF₂ crystal was applied in acousto-optically Q-switched laser at mid-infrared region for the first time. Using a TeO₂-based crystal as Q-switcher, we obtained a laser diode (LD) end-pumped Er:CaF₂ laser with the highest single pulse energy up to 0.49 mJ and maximum peak power of 0.56 kW under 6.34-W absorbed pump power. The implication of these results is that the low-doped Er:CaF₂ crystal exhibits promising optical properties in solid-state lasers.