Pr:YLF, intracavity-pumped, room-temperature upconversion laser

Cw room-temperature upconversion laser operation is reported in Pr:YLF at 640 and 607 nm. An intracavitypumping scheme that uses a Yb:YAG laser operating at 1030 nm to pump the weak (3)H(4) ? (1)G(4) ground-state transition of Pr:YLF is used to populate the intermediate metastable level. An excited-state absorption at 867 nm is then used to populate the (3)P(0) and (3)P(1) upper states. An average output power of 3.5 mW was obtained at 607 nm, with a combined input pump power of 2.5 W.