Effect of Fe concentration on the nonlinear refraction and reverse saturable absorption in ferroelectric X-cut LiNbO3 crystal

In this Letter, the effects of the iron (Fe) dopant concentration on the nonlinear optical properties of iron-doped ferroelectric X-cut LiNbO3 crystals plates are studied by using the Z-scan technique with a cw laser at the wavelength of 532 nm. The amount of iron in the compound is varied from 0 to 0.15 mol%. Measurements of nonlinear refractive index 17.7 and the nonlinear absorption coefficient fi are determined. The sign of the nonlinear refractive index is found to be negative and the magnitude is on the order of 10(-8) cm(2)/W. This nonlinear effect increases as the concentration increases from 0 to 0.15 mol%. A good linear relationship is obtained between nonlinear refractive index, nonlinear absorption coefficient, and concentration.