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ArF-excimer-laser-induced absorption and emission bands in type-III fused silica synthesized under oxidizing conditions were investigated. The fused silica irradiated with the ArF excimer laser shows an absorption band at 4.8 eV and an emission band at 1.9 eV, which are considered to be created by oxygen molecules dissolved in the glass. In addition to these bands, an absorption band at 2.0 eV ascribed to the nonbridging-oxygen hole center is observed. Solarization is enhanced strongly by annealing in He ambient. Based on these results, we proposed a model to describe the phenomena: H20 molecules bound to the = Si -OH structure by hydrogen bonds creates oxygen molecules which are considered to be precursors of the 4.8and the 1.9-eV bands.PACS number(s): 71.25. Mg, 42.55. 6p

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The energy-density and repetition-rate dependences of the intensity of KrF-excimer-laser (5.0 eV) -induced 1.9-eV emission band in type-III fused silicas synthesized under different conditions were investigated. The intensity of the 1.9-eV band is proportional to the 1.7-th power of the energy density and the 0.6-th power of the repetition rate of the laser pulse. The origin of these dependencies was discussed based on the trapped-oxygen-molecule model proposed by Awazu and Kawazoe; by irradiating with the excimer laser, ozone molecules are formed from dissolved oxygen molecules and 1.9-eV photons are emitted in the course of the photodecomposition of the ozone molecules. Therefore, a two-step photonabsorption process is needed to emit the 1.9-eV photon. To form the ozone molecule, diffusion of the oxygen atoms produced by the photodecomposition of the trapped oxygen molecules are needed. This model suggests that the intensity of the 1.9-eV band is proportional to the square of the energy density and the square root of the repetition rate; this dependency is nearly the same as that of our experimental result.

Luminescence and absorption characteristics of fused silica are investigated for obtaining an optical material for an ArF excimer laser. Fused silica synthesized in a oxygen rich atmosphare shows a strong luminescence band at 650 nm. This band can be annihilated by annealing in a hydrogen atmosphare, but appears again by subsequent annealing in air. Fused silica synthesized in a hydrogen rich atmosphare show a strong luminescence band at 280 nm, which correlates the 220 nm absorption band caused by the E' center. The 280 nm luminescence band and the 220 nm absorption band disappeare by annealing in a herium atmosphare. Fused silica for ArF laser optics can thus be obtained by annealing fused silica synthesized in a hydrogen rich atmosphare in herium .