Processing of dielectric materials with shaped, ultrashort pulses and THz pulse trains

Summary form only given. Ultrashort pulsed laser excitation of dielectrics has evidenced a material dependent response to radiation, reflected in individualized times necessary to deposit the laser energy into the lattice. Electronic mechanisms are observed in the ultrafast ablation of dielectrics, dependent on either electrostatic energy accumulation in the upper layers following intense photoelectron emission and surface break-up by Coulomb explosion, or excitation-induced lattice displacements associated with defect formation and electron trapping. These non-thermal channels for energy deposition compete with the thermal channels based on electron-phonon coupling with result in local heating. A presentation of the time scales involved in laser coupling with dielectric targets is given for a sapphire (Al/sub 2/O/sub 3/) sample.