Photosensitivity of germanosilicate fibers using 213nm, picosecond Nd:YAG radiation.

The photosensitivity of Ge-doped silica fiber using 213nm, 150ps Nd:YAG radiation, is presented here for first time. Refractive index changes greater than 10-3 were measured in Bragg grating reflectors recorded in a low-Ge content fiber, using average intensities of approximately 0.35GW/cm2. Grating growth curves for 213nm inscription wavelength are presented and discussed, in comparison with data obtained using 248nm excimer laser radiation. The experimental results presented denote that contrary to the recording using longer laser wavelengths and pulse durations, the grating inscription employing 213nm picosecond radiation is dominated by a two-photon absorption, which role becomes prominent in long-exposures.