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On the uniaxial static stress relaxation in fused silica at room temperature

The question of whether static stress in fused silica relaxes at room temperature is still under debate. Here, we report experimental data investigating stress relaxation dynamics in fused silica at room temperature and up to 2 GPa stress levels under static loading conditions. Our measurements are performed using an innovative combination of methods; a femtosecond laser is used to accurately load a monolithic microscale test beam in a non-contact manner, fabricated using femtosecond laser processing and chemical etching, while the stress is continuously monitored using photoelasticity over an extended period spanning several months, in both dry and normal atmospheric conditions. The results are of practical importance, not only for photonics devices making use of stress-induced birefringence but also for flexures subjected to static loads.