<title>157-nm laser-induced modification of fused-silica glasses</title>

Abstract

Bulk laser modification is reported for hydroxyl (OH), chlorine (Cl) and fluorine (F) containing fused-silica glasses irradiated with 157-nm F<SUB>2</SUB>-laser light. We detail the effects of OH, Cl and F concentration, as well as hydrogen (H<SUB>2</SUB>) loading, on compaction, refractive-index change, and color-center formation. Volume gratings formed with several tens of kJ/cm<SUP>2</SUP> fluence yielded surface-relief gratings of several tens of nm amplitude and bulk refractive-index changes of nearly 10<SUP>-3</SUP> in both OH- and Cl-content glasses that were pre-soaked in high-pressure hydrogen. H<SUB>2</SUB>-loading offered an approximate 2-fold increase in 157-nm glass photosensitivity, and also increased the 157-nm material absorption by several factors during the exposure. In contrast, F-doped glass did not offer a measurable 157-nm photosensitivity, and the 157-nm absorption showed a surprising order-of-magnitude drop following an approximate 10-kJ/cm<SUP>2</SUP> laser dose.