Bragg gratings have been fabricated in As(2)S(3) optical fibers through the photoinduced refractive-index change process. Bragg filters in the fiber show a more-ideal response than those fabricated in the corresponding bulk material. Some features characteristic of chalcogenide fibers and Ge-doped oxide fibers are discussed comparatively.

Photocurrent changes with light soaking have been studied in amorphous As 2 S͑Se,Te͒ 3 and Se and crystalline As 2 S 3 and Se at 10-300 K. In the chalcogenide glasses the photoconductive degradation occurs at 300 K, while at low temperatures photocurrents in subband-gap spectral regions increase with light soaking. In the crystalline samples, no such changes are detected. The photoconductive enhancement appears to be related to the photoinduced midgap absorption, and the microscopic mechanism is discussed in a unified way. The observations are also compared with those in the Staebler-Wronski effect in amorphous Si:H films.

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