Laser-matter interaction in transparent materials: Confined micro-explosion and jet formation

High intensity laser beam was tightly focussed inside bulk of dielectrics at adjustable distance from the outer boundary (1-15 μm). Laser- matter interaction region is thus confined inside a cold and dense material, with and without boundary effects. In what follows we first describe self-consistently the relevant laser-matter interaction physics. At high intensity of the laser beam in a focal region (> 6 × 10¹² W/cm²) the material is converted into a hot and dense plasma. The shock and rarefaction waves propagation, formation of a void inside the target are all described. Then, a model was developed to predict size of the voids in the bulk of materials, i.e. without boundary effects. Results were compared to experimental observations. The size of a void formed by 800 nm 150 fs laser pulses is ∼0.2 μm³. Finally we present new results in confined geometries and we show that jets can develop sizes and expansion velocities depending both on energy laser and distance from the rear surface. This jet formation regime, apparently new, can be related to some LIFT process, with submicrometer diameter jets.