We investigate the use of infrared femtosecond laser pulses to induce highly localized refractive-index changes in fused-silica glasses. We characterize the magnitude of the change as a function of exposure and measure index changes as large as 3×10<sup>-3</sup> and 5×10<sup>-3</sup> in pure fused silica and boron-doped silica, respectively. The potential of this technique for writing three-dimensional photonic structures in bulk glasses is demonstrated by the fabrication of a Y coupler within a sample of pure fused silica.
© 1999 Optical Society of America
(160.2750) Materials : Glass and other amorphous materials
(190.4180) Nonlinear optics : Multiphoton processes
(230.4000) Optical devices : Microstructure fabrication
(230.7370) Optical devices : Waveguides
(320.7130) Ultrafast optics : Ultrafast processes in condensed matter, including semiconductors
D. Homoelle, S. Wielandy, Alexander L. Gaeta, N. F. Borrelli, and Charlene Smith, "Infrared photosensitivity in silica glasses exposed to femtosecond laser pulses," Opt. Lett. 24, 1311-1313 (1999)