Behavior of 157 nm excimer-laser-induced refractive index changes in silica

摘要

This study describes the observation of large induced refractive index changes produced by 157 mn excimer laser exposure in high-purity synthetic silica glasses. With 157 nm exposure, large induced changes are observed within a few hundred thousand pulses of exposure. Similar to 193 mn exposures, exposure with polarized 157 nm light yields polarization-induced birefringence (PIB). However, the 157 mn exposure also exhibits a behavior not observed with 193 mn exposures; namely, the initial response of the glass is a decrease in refractive index, followed by an increase with continued exposure. An explanation of the behaviors for both wavelength results is proposed where the induced refractive index is considered to arise from two different concurrent phenomena. One produces a decreased refractive index and also accounts for the PIB. The other, which accounts for the increased refractive index, is associated with an isotropic laser-induced volume change. (c) 2006 Optical Society of America.