title: In situ observation of photoinduced refractive-index changes in filaments formed in glasses by femtosecond laser pulses.
abstract: We investigated the relationship between the formation of filaments and local refractive-index changes induced by femtosecond laser pulses in silica glass. In situ observation revealed that the location of a filament coincided with that of the refractive-index change. Observation also showed that the region of refractive-index change was elongated toward the upstream direction of the laser pulses with increasing exposure time. The region of refractive-index change was several hundred micrometers long, and its diameter was smaller than 2 mum. The refractive-index change was confirmed by two of three different methods to be as large as 0.8 x 10(-2).
authors.forename: K
authors.initials: K
authors.lastname: Yamada
authors.forename: W
authors.initials: W
authors.lastname: Watanabe
authors.forename: T
authors.initials: T
authors.lastname: Toma
authors.forename: K
authors.initials: K
authors.lastname: Itoh
authors.forename: J
authors.initials: J
authors.lastname: Nishii