Stimulated emission from ($F_2^+)_A$ color centers in an NaF crystal

Lasing in ($F_2^+)_A$ centers was observed when an NaF crystal was pumped with ruby laser radiation. A tunable color-center laser was constructed and its parameters were found to be as follows: tuning range 0.95–1.3 $\mu$, threshold 400 kW/cm$^2$, efficiency 15%, output power 1 MW. It was found that the ($F_2^+)_A$ centers were highly stable at room temperature. A study was made of the conversion of these ($F_2^+)_A$ centers by the high-power pump radiation and the existence of a stable component of these centers was established.