Green luminescence in silica glass: A possible indicator of subsurface fracture

We investigate the nature of defects triggering laser damage in fused silica in subsurface fracturesin nanosecond near ultraviolet regime. Mechanical, laser induced surface flaws as well as pristinesilica surface were characterized by optical microscopy and luminescence confocal microscopybefore and after acid etching. In all cases, photoluminescence decreases with etching timeassessing the existence of defects close to the surface. Spectral analysis of the evolution of thesesignals during etching allows new interpretations of the nature of precursors inducing damage.Green luminescence around 2.25 eV is seen as a potential subsurface fracture indicator leading tolaser damage