Orange and red upconversion laser pumped by an avalanche mechanism in Pr3+, Yb3+:BaY2F8

The letter reports on upconverted orange (607.5 nm, P03→3H6) and red (638.7 nm, P03→3F2) laser oscillation at room temperature observed in Pr3+, Yb3+:BaY2F8 under excitation at 822 or 841 nm at 300 K. The upconversion mechanism that populates the emitting level is an avalanche excitation mechanism. Output powers up to 55 mW and slope efficiencies up to 27% were demonstrated at 607.5 nm. At 638.7 nm, the maximum output power was 26 mW with a slope efficiency of about 13.5%.