Efstratios Georgiou

Stable color-center laser in OH-doped NaCl operating in the 1.41- to 1.81-μm region

A powerful and stable color-center laser based on a perturbed F(2)(+) center has been demonstrated in additively colored NaCl:OH(-) crystals. The OH(-) impurity has been positively identified as the key dopant for creating the color-center laser in NaCl. The laser tunes smoothly over the 1.41- to 1.81-microm region with a maximum cw power of 1.25 W when pumped by a 9-W cw Nd:YAG laser operating at 1.06 microm. Laser operation for periods of several weeks has been monitored with no observable fading in output power. In addition, mode-locked pulses of 5-psec duration have been generated in a synchronously pumped arrangement, tunable from 1.47 to 1.73 microm with an average power of 450 mW at the peak of the tuning curve.

Pulsed, room-temperature operation of a tunable NaCl color-center laser

A room-temperature, pulsed, color-center laser using OH(-)-doped NaCl crystals is reported. Crystals were transversely pumped by a Q-switched Nd:YAG laser at 1.06microm and produced output energies of 8.6 mJ in 20-nsec pulses. The tuning range extended from 1.37 to 1.77 microm. During 40 h of operation (>10(6) pulses), a gradual power fading was observed. Laser action is tentatively ascribed to F(2)(+) centers.

Recent progress in color center lasers

Recent progress in the stabilization of laser-active color centers, the discovery of new color center lasers, and the development of new femtosecond sources in the infrared is discussed. The use of impurities such as oxygen to stabilize the F2+ center is described, followed by a description of the recently discovered N-center laser. Finally, the use of color center lasers to produce femtosecond pulses in the 1.5 μm region is reviewed.

Stable, pulsed, color-center laser in pure KCl tunable from 1.23 to 1.35 μm

Stable, tunable, pulsed laser operation based on the N(2) color center in additively colored pure KCI is reported. The laser tunes smoothly from 1.23 to 1.35 microm when pumped by a 1.06-microm Q-switched Nd:YAG laser at kilohertz repetition rates. 42-mW average output power at 1.28 microm was achieved for 1-W average incident pump power. No power fading has been observed over several weeks of day-to-day operation.