Infrared photosensitivity in silica glasses exposed to femtosecond laser pulses

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 x 10(-3) and 5 x 10(-3) 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. (C) 1999 Optical Society of America OCIS codes: 320.7130, 190.4180, 230.4000, 230.7370, 160.2750.