Photosensitivity and application with 157-nm F/sub 2/ laser radiation in planar lightwave circuits

Photosensitivity studies of germanosilica planar waveguides were carried out with shortwavelength 157-nm light from an F/sub 2/ laser. More than a 5*10/sup -3/ refractiveindex change was induced in a nonuniform index profile concentrated near the claddingcore interface and confirmed by an atomic force microscopy in 157-nm radiated fiber. This profile geometry narrows with the laser exposure to offer practical application in trimming phase errors and controlling birefringence in frequency domain modulators where a 1.7*10/sup -3/ effective index change and a 5*10/sup -4/ birefringence change were induced, respectively. The 157-nm photosensitivity response is more than 15 times stronger than that by a 248-nm KrF laser and more than twofold stronger than that by a 193-nm ArF laser.