An Overview of the Thermal Erasure Mechanisms of Femtosecond Laser‐Induced Nanogratings in Silica Glass

Type II modifications induced by infrared (IR) femtosecond (fs) lasers are used in many optical devices due to their excellent thermal stability at high temperatures (typically >800 °C). The characteristic feature of type is the formation nanogratings, which easily detected through birefringence measurements. However, measured an aggregate value multiple contributions including form birefringence, stress-induced permanent volume changes, and point defects. This work investigates erasure kinetics each one these silica glass. Firstly, samples irradiated with a fs-laser using different conditions (polarization, energy). Secondly, accelerated aging experiments conducted evaluate laser-induced modifications, defects, densification, stress field, porous nanogratings. Finally, aforementioned nanogratings identified spectroscopic techniques (Raman, Rayleigh scattering, UV–vis absorption) electron microscopy. Moreover, simulated Rayleigh–Plesset equation. Herein, valuable framework realization glass-based operating (≫800 °) provided 1) evidencing effect annealing on mechanism 2) providing information response (mainly birefringence) upon annealing.