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

Weak stationary bulk absorption coefficients α^stat(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 α^stat(Φ, f = const.) for 3 ⩽ Φ ⩽ 25 mJ cm⁻² pulse⁻¹ and α^stat(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.