Decay of UV-induced fiber Bragg gratings

Ultraviolet photosensitivity in germanium-doped silicate glasses is currently an area of significant interest. In particular, UV- induced Bragg phase gratings in optical fibers have recently been demonstrated in numerous applications, such as short single-frequency fiber lasers, hybrid semiconductor-fiber lasers, polarization- and transverse-mode converters, and fiber sensors. Although these phase gratings are often described as permanent structures, the degree of permanence has not been adequately investigated. Many applications of fiber gratings, such as precise wavelength-control devices for communications systems, require extremely high tolerances on the optical properties of the gratings over long times. Some applications might also require operation at elevated temperatures, thus posing additional environmental wear.