Photosensitivity in optical fiber waveguides: Application to reflection filter fabrication

The observation of photosensitivity in Ge-doped core optical fibers is reported. The photosensitivity is manifested by light-induced refractive-index changes in the core of the waveguide. Narrowband reflectors in a guide structure have been fabricated using this photosensitivity and the resulting DFB reflectors employed as laser mirrors in a cw gas laser in the visible.