Dynamic Bragg gratings induced in erbium-doped fiber at phase-Modulated beams' coupling

We present the results of an experimental study of dynamic amplitude and phase Bragg gratings induced in a heavy-doped erbium fiber at the wavelengths 1532 and 1538 nm under the 980-nm pumping. The technique of two phase-modulated beams' coupling was applied for an experimental measurement of the changes in refractive index and gain accompanying the gratings' formation in the fiber, and an analysis based on the Kramers-Kronig Relations for the fiber absorption/gain spectra and two-pass amplifying was performed for modeling these changes.