Phase population gratings recorded in ytterbium doped fiber at 1064 nm

For the first time, the experimental results on spatially uniform photo-induced refractive index changes Δn induced in ytterbium-doped optical fiber at the wavelength λ= 1064 nm were obtained and directly compared with the efficiency of the transient two-wave mixing (TWM) via phase population grating. It is shown that the TWM efficiency is in a reasonably good accordance with the theoretical evaluation based on the Dn measurements. Similar correspondence was also observed for a significantly weaker spatially uniform saturation of the fiber optical absorption and the TWM efficiency via absorption type population gratings. In contrast to similar data obtained earlier for erbium doped fibers, this allows us to assume that spatial diffusion of the excited state among Yb3+ is significantly less efficient than among Er3+ ions.