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

TL;DR

This study investigates whether static stress in fused silica relaxes at room temperature, using innovative non-contact methods to monitor stress over months, with implications for photonics and mechanical applications.

Contribution

It provides experimental evidence on stress relaxation in fused silica at room temperature and high stress levels, using a novel combination of laser loading and photoelastic monitoring.

Findings

Stress relaxation occurs in fused silica at room temperature.

Stress levels up to 2 GPa do not prevent relaxation.

Results are relevant for photonics and mechanical device design.

Abstract

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.