Coefficients of stationary ArF laser pulse absorption in fused silica (type III)

Weak stationary bulk absorption coefficients αstat(Φ, f) in fused silica are measured directly in dependence on the ArF laser fluence Φ and repetition rate f by the laser induced deflection technique (LID). The absorption is quantified using a modified Beer’s law. The investigated samples show non-linear increases αstat(Φ, f = const.) for 3 ⩽ Φ ⩽ 25 mJ cm−2 pulse−1 and αstat(Φ = const., f) for 50 ⩽ f ⩽ 400 Hz. The experimental data are fitted by a rate equation model consisting of an equilibrium between E′ center generation and annealing. Generation occurs photolytically from SiH and strained SiO bonds via 1- and 2-photon absorption, respectively. Annealing is due to the reaction with atomic hydrogen and other reaction channels, e.g. ODC generation.