Ultraviolet-induced distributed-feedback gratings in Ce^3+-doped silica optical fibers

Abstract

Nondegenerate four-wave mixing was used to write permanent distributed-feedback refractive-index gratings in a Ce3+-doped (80 parts in 106), aluminosilicate, single-mode glass optical fibser at 300 K with a corresponding change in the refractive index Δn = 2.5 × 10−5 at 808 nm. Direct excitation of the 2F5/2−5d transition at 292 nm results in the photoionization of Ce3+ and the creation of color centers. The photoinduced absorption recovered on wavelength-dependent time scales ranging from seconds to hours. Below approximately 450 nm the recovery was incomplete, which contributed to the observed refractive-index change.