Cryogenically cooled 2.8 μm Er:YAP laser with watt-level output power

Abstract

We report the first watt-level, cryogenically cooled Er:YAP laser operating in the 3 μm spectral region. The spectroscopic properties of a 5 at% Er:YAP crystal were studied at cooling temperatures ranging from 77–290 K. The fluorescence lifetime of the 4I11/2 level associated with the 3 μm laser transition decreased with an increase in temperature; whereas, the lifetime of the 4I13/2 level increased with an increase in temperature. Moreover, over 1 W of output power at 2798 nm was achieved from the liquid-nitrogen-cooled Er:YAP laser with a slope efficiency of 20%, and the limitations to higher output power were discussed.