Micromachined drilling of dielectric substrates of varying bandgap using laser accelerated particles

It has been observed that absorbing particles accelerated by Continuous Wave (CW) lasers initiate catastrophic failure in the form of micromachined drill holes. This process was tested using stainless steel, PMMA, and silica particles with fused silica, sapphire, and spinel substrates. Hole drilling occurred at laser power densities as low as 250kW/cm2, far below the damage thresholds seen in typical situations. A potential dependence of accelerated particle breakdown on substrate bandgap may suggest that the underlying physical process is similar to that seen for CW laser breakdown of contaminated optical coatings.