Ultraviolet-induced densification in fused silica

Abstract

Ultraviolet-induced densification in fused silica is investigated using birefringence measurements to detect compaction-induced strain. This technique is capable of measuring compaction in the 10 parts per billion range in cm-sized specimens. A universal relation describing ultraviolet-induced compaction is discovered in which, using the total energy absorbed from two-photon absorption as the dose parameter, density changes equal a material dependent constant times the dose parameter to a power of about 0.65. This dose dependence is consistent with past compaction studies using electron beam and gamma radiation. Moreover, the density change per ionization “event” is found to be consistent for all radiation types. By comparing density measurements to refractive index change measurements found with interferometry, polarizability changes from ultraviolet-induced densification are extracted and compared with previous results using other radiation sources and inelastic densification methods.

UV-laser-induced densification of fused silica: a molecular dynamics study

“…In the present study, we use, k = 193 nm and exclusively two-photon absorp- Table 1 Atomic parameters in modified BKS potential tion [7,20], i.e., DE in Eq. (6) is 12.8 eV for each absorption.…”

“…Then it is trivial to solve for the rest of the unknowns from Eqs. (6) and (7). To ensure that all the roots are real, the randomly assigned velocities v x Si and v y Si have to satisfy the following relation:…”

“…In 1986, for the first time, Fiori and Devine studied 248 nm laser-induced changes in a-SiO 2 thin films with a laser fluence of 300 mJ/cm 2 [5]. Since then, intensive experimental efforts have been undertaken to study UV-laser-induced densification of bulk fused silica [1,[6][7][8][9][10][11]. Though several empirical relationships between induced densification and applied laser doses have been proposed and have similar forms, the mechanism of UV-laser-induced densification in fused silica still remains unclear and poorly understood.…”

Fs Laser Induced Reversible and Irreversible Processes in Transparent Bulk Material

“…It is well established that intensive laser action on the amorphous matrix of glass can lead to irreversible variation in the refractive index n [29,30]. The Chap.…”

Sn O 2 nanoparticles in silica: Nanosized tools for femtosecond-laser machining of refractive index patterns

“…This ratio is 0.33 for a pure photoelastic response and 0.19 for UV-induced silica compaction. 15 This suggests that the process differs from the UV-induced compaction of silica, specifically for a larger contribution of elastic compression ascribable to the reaction against the nanophase amorphization.…”