We report a large increase in photosensitivity of germanium-doped silicate fibers by rapid heat treatment of hydrogen-loaded fibers at 1000 °C before exposure of the fibers to 242-nm radiation. The increase in photosensitivity is compared with thermally induced absorption caused by introduction of massive amounts of hydroxyl species. The absorption loss was measured to be 0.02 dB/cm mol.% OH at 1.55 μm. Strong gratings (Δ<i>n</i> > 1 × 10<sup>-4</sup>) in germanium-free phosphorous-doped fibers in the presence of 242-nm radiation have also been manufactured by this technique.
© 2000 Optical Society of America
(050.1950) Diffraction and gratings : Diffraction gratings
(060.2290) Fiber optics and optical communications : Fiber materials
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(060.2400) Fiber optics and optical communications : Fiber properties
Michael Fokine and Walter Margulis, "Large increase in photosensitivity through massive hydroxyl formation," Opt. Lett. 25, 302-304 (2000)