Stable color-center laser in K-doped NaCl tunable from 1.42 to 1.76 microm

Stable, broadly tunable cw lasing has been obtained from color centers in additively colored NaCl doped with K. The laser tunes from 1.42 to 1.76 microm with a peak output power of 530 mW when pumped by 6 W from a 1.06-microm Nd:YAG laser. Output power is strongly enhanced by exposing the crystal to an auxiliary UV light during lasing. No fading of output power has been observed over extended periods. The laser operates at 77 K; however, the crystals can be stored at room temperature. The active color center is tentatively identified as an (F(2)(+))(A) center.