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

Abstract

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.

The characteristics of dynamic gratings in ultra-narrow linewidth erbium-doped fiber ring lasers

“…the lasing frequency shift resulting from the drifts of the laser cavity length deteriorates the reflectance spectrum of the dynamical gratings and subsequently the mode stability of lasers. Some techniques have been proposed to measure reflection/transmission characteristics of dynamics gratings, such as the four-wave mixing (FWM) configuration ("pump-and-probe" configuration) [2][7] [10] , two-wave mixing (TWM) with phase/intensity modulation [8] [9][11] [12] , etc. The FWM configuration can measure reflectance spectrum of dynamic gratings in stationary state, while the TWM configuration is used to detect the reflectivity at a certain frequency.…”