Speaker
Description
TeO2-based glass have large optical nonlinearities and a wider transparency window, showing second order harmonic generation (SHG) that are promising photonics applications.
Here, we investigate the physical mechanism leading the formation of self-organized nanostructures under femtosecond laser exposures of a TeO2-based glass surface and subsurface under different laser parameters.
In practice, repetitive laser patterns were written on the surface and in the bulk of tellurite glass using 270 fs-femtosecond laser pulses. The effect of the repetition rate, pulse energy, translation velocity were selected as main process parameters to explore laser-induced microstructures.
Specifically, we report on characteristic morphologies, elemental analysis and structural bond arrangements within the laser-modified areas. At low-repetition rate, we show that self-organized nanostructures consisting of parallel nanoplanes perpendicular to the laser polarization are forming in the focal volume, while self-organized nanostructures extend well beyond the zone under direct laser exposure at high repetition rate. We observed that such irradiation lead to bond rearrangements and subsequent changes in the material properties in both rates. Further examination of the modified regions revealed evidences of phase changes, from a glassy tellurium oxide phase to a crystalline metallic tellurium one, associated with elemental dissociation due to strong thermal and pressure effect, followed by fast cooling during laser inscription. In addition, the self-organization process is associated with elemental redistribution and reversible deoxygenation, itself triggered by the optical-field strength. To understand the physics of the process, the formation mechanism of these self-organized nanostructures is highlighted. These results give new insights toward a better understanding of laser-induced modifications in tellurite glass in the ultrafast exposure regime.
| Speaker Country | Switzerland |
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