We argue that the conclusion of Borrelli [J. Opt. Soc. Am. B 16, 1672–1679 (1999)] in favor of a negligible contribution of the UV-induced densification to the refractive index change raises questions for the following reasons: (i) The use of a relation between index change and inelastic strains is inadequate to the problem of UV exposure, (ii) the authors claim to describe the process in fiber but forget to take into account the mechanical reaction of the cladding, and (iii) the authors transfer results obtained in oxidized bulk samples to reduced fiber glass.
© 2002 Optical Society of America
Bertrand Poumellec and Pierre Niay, "Direct measurement of 248- and 193-nm excimer-induced densification in silica–germania waveguide blanks: comment," J. Opt. Soc. Am. B 19, 2039-2041 (2002)