Formation of nanogratings driven by ultrafast laser irradiation in mid-IR heavy oxide glasses

This work demonstrates for the first time formation of nanogratings inside Barium Gallo-Germanate (BGG) glasses using femtosecond laser direct writing. These heavy oxide glasses, with a characterized transparency window up to 6 μm, along polarization sensitive birefringent nanostructures induced by laser, offer an excellent platform development mid-Infrared photonic applications. The fabricated containing both rare earth elements (Gd, Y) and transition metals (Zn, Ta), are directly compared amorphous GeO2 commercial alumino-germanate (Corning-9754) commonly used in this field. processing each glass was investigated varying parameters (pulse duration, energy, repetition rate), electron microscopy imaging evidenced porous nanostructures. Among results, strong form birefringence 8% ZnO BGG glass, e.g., −0.029 ± 0.001, reported. Finally, embedded Fresnel GRIN plates were written demonstrate functionalization potential these materials.