COMPLEX PHOTOSENSITIVITY OBSERVED IN GERMANOSILICA PLANAR WAVE-GUIDES

Photosensitive effects distinguished as type I and type IIA photosensi tivity within optical fibers were observed in a much more pronounced f orm within germanosilica waveguides deposited by hollow-cathode plasma -enhanced chemical-vapor deposition. With increasing exposure to 193-n m UV light, positive index changes greater than 2 x 10(-3) were observ ed, followed by negative index changes greater than -5 x 10(-3). These behaviors are attributed to an increase in macroscopic polarizability and a reduction in material density, respectively. The negative index change is more temperature resistant and is fully annealed only at 90 0 degrees C, whereas the positive one is annealed at 500 degrees C. (C ) 1998 Optical Society of America.