AG-EARTH FLUORIDES - NEW UV SOLID-STATE LASERS( CENTER IN ALKALINE)

Oxygen-free strontium fluoride crystals containing single monovalent s ilver ions in a cubic site were grown. Our experiments showed that the Ag+ ion remained chemically stable upon optical irradiation at 222 nm (KrCl excimer). The ion exhibits a strong UV luminescence which prese nts no thermal quenching up to RT. At this temperature, the emitting l evel time-constant is 12 mu s. An explanation is proposed for the silv er photostability by relating it to the large electronic bandgap of th e host (11.4 ev). The 222 Mn absorbing level lies below the conduction band in a way such that photoionization of Ag+ is avoided, as well as other optically-induced opacity phenomena. A minimum source intensity at threshold is estimated at some 276 kW, when using a Fabry-Perot ca vity. This power can normally be achieved with the excimer laser.