Spectroscopic characterization and laser performance of diffusion doped Cr2+:ZnS

Spectroscopic, saturation, and laser properties of diffusion doped Cr2+:ZnS crystals synthesized by chemical reaction from gas phase are reported. Lasing was realized with a threshold of 170 muJ and slope efficiency of 9.5% with respect to the 1.5607 mum pump energy, in a hemispherical cavity. Maximum output energy reached 100 pJ. A tuning range of 2.05-2.40 mum was realized, limited by the spectral range of the output coupler of the selective hemispherical laser cavity. Selective cavity experiments used a CaF2 prism as the dispersive element. Findlay Clay losses were found to be about 14%. Absorption cross section (0.80x10(-18) cm(2)) was estimated from spectroscopic measurements and was in good agreement with saturation data, calculated with the modified Frantz-Nodvik equation for a four level slow absorber.