Green infrared‐pumped erbium upconversion laser

An upconversion pumping scheme was used to produce cw laser action at 0.55 μm in YAlO₃:Er³⁺ at temperatures up to 77 K on the ⁴S_3/2→⁴I_15/2 transition. Two infrared dye lasers at 792.1 and 839.8 nm were used as the pump sources for stepwise two‐photon excitation of the ⁴S_3/2 upper laser level at 18 406 cm⁻¹. The laser operates in the fundamental TEM₀₀ mode, and a cw output power of ∼1 mW was achieved with ∼200 mW pump power from each infrared dye laser.