Laser oscillation by the F2+ and F2- color centers in LiF crystals

A free-running mode LiF:F-2(+) color center laser oscillation is achieved at room temperature in an elcctron-beam-irradiated LiF crystal with the F-2 color centers but no F-2(+) ones, by producing the F-2(+) defects through the two-photon excitation of the F-2 centers and pumping the F-2(+) defects with the same wavelength. Simultaneous laser oscillation by the F-2 center is obtained at the initial stage of the F-2(+) lasing but it disappears 100 s after the pumping. The LiF:F-2(+) laser operating at 930 nm is used to pump an F-2(-) color center laser based on a different elcctron-beam-irradiated LiF crystal with high concentration of the F-2(-) centers. A free-running F2- pulse laser oscillation with a peak at 1145 nm and a half width of 400 cm(-1) is achieved. (C) 2000 Elsevier Science B.V. All rights reserved.