Abnormal temperature dependent elastic properties of fused silica irradiated by ultrafast lasers

Materials with thermal-invariant elastic properties are of interest for resonant device frequency and dimensional stability of precision devices. Here, we demonstrate that the temperature coefficient of elasticity (TCE) of amorphous silica can be locally reduced using femtosecond laser irradiation. Notably, a self-organized laser-induced modification shows a decrease of the TCE beyond 50%. The origin of this dramatic decrease is attributed to the presence of submicron permanent densified zones within the fine multilayer structure of the laser-modified zone.