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.

High power Er:YAP laser at 2.92 μm based on incoherent beam combining

“…18,19) Nevertheless, in addition to its complex cooling system, the low temperature will change the laser energy level and generate a center wavelength of 2.8 μm. 20) YAP crystals have low phonon energy (550 cm −1 ) and excellent physical properties, enabling the high-power MIR laser operation. 21) Most notably, compared with commonly used isotropic garnet materials such as YAG, YAP crystals are optically biaxial and anisotropic, and their thermal conductivities along the a-, b-and c-axes are 11.7, 10.0 and 13.3 W m −1 K −1 , respectively.…”