Thermal stability of nanogratings in oxide glasses: a route to overcome silica

This paper provides an overview of the thermal stability of volume nanogratings (NGs) inscribed in more than 20 laboratory and commercial oxide glasses using femtosecond laser pulses. The role of glass composition and its viscosity-temperature dependence are particularly investigated. Other parameters, such as nanostructure morphology (e.g., porosity size) can play a role in it. Although it has become established that high viscosity glasses typically yield improved thermal stability, recent results highlight deviations from this trend. This is particularly pronounced in low SiO₂ containing glasses with large Al₂O₃ content (typ. > 50 mol%), where their NGs thermal stability is comparatively higher than what is known for pure silica, which may prove useful for optical devices operating in extreme environments.