Writing waveguides and gratings in silica and related materials by a femtosecond laser

With the goal of creating various optical glass devices for the telecommunications industry, the effects of 810 nm, femtosecond laser radiation on various glasses were investigated. By focusing the laser beam via a microscope objective, transparent but visible, round-elliptical damage lines were successfully written inside high silica, berate, soda-lime-silicate, fluoride and chalcogenide glasses. Microscopic ellipsometric measurements of the damaged region in pure and Ge-doped silica glasses showed refractive index increases of 0.01 to 0.035. The formation of several types of defects, including Si E' or Ge E' centers, non-bridging oxygen hole centers, and peroxy radicals, was also detected in addition to the identification. These results suggest that multi-photon interactions occurs in the glasses and that it is possible to write three-dimensional optical circuits in bulk glasses via such a focused laser beam technique. (C) 1998 Elsevier Science B.V. All rights reserved.