Color center production by femtosecond pulse laser irradiation in LiF crystals.

We report the production of color centers in LiF single crystals by ultrashort high intensity laser pulses (60fs, 10 GW). An intensity threshold for color centers creation of 2 TW/cm(2) was determined, which is slightly smaller than the continuum generation threshold. We could identify a large amount of F centers that gave rise to aggregates such as F(2), F(2) (+) and F(3) (+). The proposed mechanism of formation is based on multiphoton excitation that also produce short lived F(2) (+) centers. It is also shown that it is possible to write tracks in the LiF crystals with dimensional control.