Effect of F 2 laser power on defect formation in high-purity SiO 2 glass

Abstract

Laser power dependence of defect formation in synthetic SiO 2 glass by F 2 laser irradiation was measured. Concentration of the E ′ center dissociated from the strained Si–O–Si bond was almost proportional to the F 2 laser power less than ∼10 mJ cm −2 pulse −1 (∼0.5 MW cm −2). However, it increased as nearly square of the F 2 laser power above the threshold. Quantum yield of formation of the E ′ center by two-photon absorption of F 2 laser light was ∼3 orders of magnitude larger than that of the KrF or ArF laser light, and we suggest that two-step absorption of F 2 laser photons via real intermediate states dominates the formation of the E ′ center.