Theory of Third-Order Optical Susceptibility in Magnesium Doped Lithium Niobate Crystal
Namita Sisodia, Rashmi Trivedi, P. K. Sen, K. S. Bartwal and Pratima Sen
In the present paper, we have developed a theoretical model to examine the effect of MgO doping on the third-order nonlinearity in congruently grown LN crystals. The bound electron contribution as well as photorefractive effects have been incorporated. Due considerations is also given to the thermal nonlinearity. We find that the change in the sign of the nonlinear refractive index of MgLN crystal observed experimentally can be assigned to the photorefractive effect in ferroelectric media.
Keywords: Photorefractive material, ferroelectric material, nonlinear optics, optical susceptibility, self- focusing and defocusing.
PACS numbers: 42.70.Nq, 42.70.Mp, 42.65.-k, 42.65.An, 42.65.Jx