Microexplosions in Tellurite glasses

Abstract:

Femtosecond laser pulses were used to produce localized damage in the bulk and near the surface of baseline, Al2O3-doped, and La2O3-doped sodium tellurite glasses. Single or multiple laser pulses were nonlinearly absorbed in the focal volume by the glass, leading to permanent changes in the material at the focal volume. These changes are caused by an explosive expansion of the ionized material in the focal volume into the surrounding material, i.e., a microexplosion. Writing of simple structures (periodic array of voxels, as well as lines) was demonstrated. The regions of microexplosion and writing were characterized using scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and atomic force microscopy (AFM) postmortem. Fingerprints of microexplosions (concentric lines within the region and a concentric ring outside the region), due to the shock wave generated during microexplosions, were evident. In the case of the baseline glass, no chemistry change was observed within the region of the microexplosion. However, Al2O3-doped and La2O3-doped glasses showed depletion of the dopant from the edge to the center of the region of the microexplosions, indicating chemistry gradient within the regions. Interrogation of the bulk- and laser-treated regions using micro- Raman spectroscopy revealed no structural change due to the microexplosions and writing within these glasses.