Z-scan investigations of photorefractive nonlinearity within doped surface layer of lithium niobate samples

The simple Z-scan experiments is an effective tool for investigations of nonlinear optical properties of different materials. In this paper Z-scan technique is used to investigate the photorefractive optical nonlinearity of lithium niobate (LiNbO
₃
) with surface doping by both, iron (Fe) and copper (Cu) ions