Infrared femtosecond laser pulse-induced functional color centers and waveguide in alkali halide crystal

We report on functional color centers and waveguide formed by using 800nm, 120fs, 200kHz pulse laser in alkali halide crystals such as KCl and LiF. These crystals are transparent in the wavelength ranging from 250-1000nm. After irradiated by the 800nm tightly focused femtosecond laser, the crystal changed to dark and color centers have been formed. Some of these color centers are useful and alkali halide crystal with these color centers is one type of laser crystal (color center laser crystal). And also photoinduced refractive index changes have been formed by focusing the laser beam.