Optical damage of the surface of sodium and potassium chlorides by femtosecond laser pulses

Optical damage thresholds for the surface of sodium and potassium chloride crystals irradiated by 80-fs laser pulses have been determined. P -polarized terawatt radiation of a chromium-forsterite laser operating at a wavelength of 1240 nm was incident on a sample surface at an angle of 35°. The optical damage of the crystal surface was observed when the electric field strength reached a critical level of 76 MV/cm for NaCl and 64 MV/cm for KCl.