Picosecond emission by a synchronous-pumping color-center laser Dynamics of F2/+/ centers during picosecond irradiation

The first production of picosecond pulses in a laser using F2(+) centers in LiF at room temperature is reported. Photodestruction of the centers was observed upon irradiation of the crystal with a neodymium-doped, phosphate-glass laser's second harmonic. The dynamics of the color centers in the LiF crystals were then monitored at various pump power densities. The results of the experiment show that the average length of the pulses in the train emitted by the color-center laser varies over a broad range, from a few hundred picoseconds to values near the length of the pump pulses, as the length of the resonator is varied. Comparison of these values shows that the F2(+) centers decay because of the intense radiation in the case of the picosecond pumping, while the primary mechanism for the decay is the photoionization of F2(+) centers through many-photon or many-cascade absorption.