Operando X-ray diffraction reveals crystallization in amorphous TeO2 glasses upon laser micro-machining

Among recent novel advanced manufacturing techniques, femtosecond (fs) laser processing gained a lot of attention due to its applicability to a variety of substrates and unique ability to locally process transparent materials in the bulk. The laser-induced taxonomy of structural modifications is rich and, despite the brevity of laser-matter interaction, includes nano-crystallization events. Yet, the mechanism leading to such phenomena driven by locally extreme exposure conditions, similar to warm-dense state of matter, remains elusive.

Thus, understanding phase transitions initiated by fs infrared (IR) lasers is key to tailor the properties of modified volumes. In tellurite-based glasses, the interaction with an IR laser leads to metallic grains inside the dielectric. These transformations lead to local changes in electrical conductivity, enabling the design of conducting channels in an insulating material. Near the surface, the transformations also show photoconductive functionalization.

I show in situ nano-crystallization dynamics initiated by non-linear material interaction of an ultrafast IR laser with the glass 80TeO₂-10WO₃-10K₂O (mol%, TWK) studied via operando X-ray microdiffraction. The measurements enable identification of crystalline phases formed in the dielectric originating from modification via non-linear laser absorption. We apply different laser absorption conditions varying the repetition rates, pulse sequences, and pulse energies for one modification voxel.