Behavior of fused silica irradiated by low level 193 nm excimer laser for tens of billions of pulses

Compaction versus expansion behavior related to the OH-content of synthetic fused silica under prolonged UV-laser irradiation

“…The impact of molecular hydrogen (H 2 ), could not be confirmed, at least for the surveyed concentration range. The linear development of rarefaction on the number of laser pulses is consistent with prior results [16]. While investigations done with gamma-irradiation [20], which are of course not directly applicable here, have shown saturation levels of several ppm, no saturation of rarefaction has been observed up to 20 billion laser pulses.…”

“…Prior investigations [16,[18][19][20] indicate that the compaction and rarefaction behavior of fused silica is linked to the content of molecular hydrogen and hydroxyl groups. To study the dependence of rarefaction and compaction on these two parameters a matrix of samples from synthetic fused silica with different levels of OH and H 2 was prepared (see Table 1).…”

“…Up to now, few studies have been performed at the very low energy density level but with the high number of pulses which are applied in a stepper. In a joint project of International Sematech and Cymer, Inc. [16,17] several grades of synthetic fused silica were irradiated with up to 40 · 10 9 laser shots at 193 nm with energy densities as low as 100 lJ/cm 2 . During this test, some samples showed an unexpected behavior: instead of an increase of the optical path in the irradiated region, a decrease of the optical path was observed.…”

Ultraviolet-induced birefringence in hydrogen-loaded optical fiber

“…9 More direct experimental evidence of dilation in bulk nonphosphosilicate glass irradiated with low-energy exciplex emission, in the one-photon excitation regime, from an ArF laser has been reported. 10 At low fluencies rarefaction, or dilation, is observed and the bulk induced birefringence follows the laser polarization though the authors were not entirely convinced of the connection. At higher fluencies, densification is observed and a tangential vector in the bulk birefringence associated with stress around the densified region was mapped.…”

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

“…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.…”