Strain and stress dynamics of femtosecond laser bulk processing of transparent fcc crystals

Abstract

Strain and stress dynamics after photoexcitation by a focused femtosecond laser pulse inside various transparent solids (sodalime glass, MgO, LiF, NaCl and CaF2 single crystals) were observed by a pump-probe polarization microscopy. The observation showed that a stress wave was generated from the photoexcited region and the shape of the stress wave depended on materials. The shapes of the stress waves could be explained by the anisotropic velocity of elastic waves calculated using elastic constants. In addition, the observation showed that the strain distribution was changed by crack generation. The origins of the differences in the observed strain distributions were discussed based on the anisotropies of elastic properties of crystals.Strain and stress dynamics after photoexcitation by a focused femtosecond laser pulse inside various transparent solids (sodalime glass, MgO, LiF, NaCl and CaF2 single crystals) were observed by a pump-probe polarization microscopy. The observation showed that a stress wave was generated from the photoexcited region and the shape of the stress wave depended on materials. The shapes of the stress waves could be explained by the anisotropic velocity of elastic waves calculated using elastic constants. In addition, the observation showed that the strain distribution was changed by crack generation. The origins of the differences in the observed strain distributions were discussed based on the anisotropies of elastic properties of crystals.