  We report on the experimental observation of selective delamination of
semi-transparent materials on the example of yttria-stabilized zirconia
ceramics upon femtosecond laser processing of its surface with low numerical
aperture lens. The delamination of a ceramic layer of dozens of micrometers
takes place as a by-side effect of surface processing and is observed above the
surface ablation threshold. The onset of delamination (delamination threshold)
depends on the degree of overlap of the irradiation spots from consecutive
laser pulses upon beam scanning over material surface. Analysis of the
delaminated layer indicates that the material undergoes melting on its both
surfaces. The mechanism of delamination is identified as a complex interplay
between the optical response of laser-generated free-electron plasma and
nonlinear effects upon laser beam propagation in semi-transparent ceramics. The
discovered effect enables controllable laser microslicing of brittle ceramic
materials.
