Photoinduced refractive index subgratings in germanosilicate optical fibers

Abstract

A new approach assuming nonadditive action of different mechanisms of the photorefractive effect is proposed to explain the features of fiber Bragg gratings (FBG) in germanosilicate fibers. By taking properly into account the properties of Ge-related defects, the causes of some discrepancies among the previous inferences about FBG are analyzed. The known mechanisms of the photorefractive effect are discussed from the point of view of superposition of subgratings, created by them. The published facts pointing to significant contribution of spatially periodic charge grating to (Delta) n are reviewed. To explain this contribution, an electrostriction mechanism is proposed. The results on FBG writing by laser radiation in the wavelength range 333 - 364 nm and new relevant data on the nature of germanium oxygen-deficient centers are discussed.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.