Spectral Properties of Dynamic Population Gratings in Ytterbium-Doped Fibers

The spectral and phase properties of dynamic population gratings in various samples of ytterbium-doped fibers at various powers of writing radiation and pumping radiation are studied. It turned out that, despite the differences between the samples, the power dependences are similar, which is determined by the gain in the fiber and the saturation power in it. It is shown that the phase of the dynamic grating takes on a constant value, changing it only at the moment of transition of the absorption grating to the gain one. The significant influence of the phase component in dynamic population gratings for ytterbium ions is experimentally demonstrated.