Stimulated Emission at an Orange Wavelength from Cryogenically Cooled Pr3+-Doped LiYF4 and Y3Al5O12

Efficient stimulated emissions at an orange wavelength (604 nm) are obtainable from a cryogenically cooled Pr:LiYF 4 crystal pumped by a 444 nm pulse laser. The red lasing at 639 nm, which is dominant at room temperature, decreases as the crystal temperature decreases. The orange laser power exceeds the red laser at temperatures lower than 180 K. At 20 K, we obtain laser oscillation without an external cavity from a 10-mm-long crystal. Such efficient lasing is ascribed to the substantial absorption reduction at 604 nm at low temperatures. We can also obtain the orange (616 nm) laser from a Pr:Y 3 Al 5 O 12 (YAG) crystal at <100 K.