Efficient cryogenic mid-IR and eye-safe Er:YAG laser

We report the first diode-pumped, continuous-wave cascaded dual-wavelength operation of an ${\mathrm{Er}}^{3+}\text{:}\mathrm{YAG}$ cryogenic laser emitting simultaneously at $\sim$ mid-IR 2.7 and eye-safe 1.6 μm. The laser is capable of delivering 45 and 10 W at 1.62 and 2.73 μm wavelength, with slope efficiencies $\sim 15\%$ and 55%, respectively. The overall efficiency with respect to the absorbed $\sim 960\mathrm{nm}$ pump power was 71%. Detailed analysis of the output power, efficiency, wavelengths, and relevant spectroscopic data is also presented.