<title>Inorganic clay-based nanostructured material for nonlinear optical waveguides</title>

Abstract

A novel Laponite-lithium iodate nanocomposite has been synthesized for nonlinear optical applications. The elaboration starts with the addition of a lithium iodate aqueous solution to a colloidal suspension of Laponite JS. Thin layers, elaborated using the dip-coating technique, form waveguides and the linear dependence between the lithium iodate concentration and the refractive index and the control over the thickness allow one to optimize waveguiding properties. Waveguides show an attenuation of about 2 dB/cm and easily detectable second harmonic generation. For the nonlinear effective coefficient a value of 1.6 pm/V has been measured. X-ray structural characterization shows that after drying and heat-treatment between 150 and 200°C, lithium iodate crystallizes in the matrix with the crystallite size ranging from 20 to 50 nm. Due to the natural dipole moment of lithium iodate, the orientation of nanocrystals could be controlled using external electric field. The influence of the orientation on the nonlinear optical properties has been determined and compared with the simulations based on a matrix model considering the nanocomposite as a stack of linear and nonlinear 1D layers with fixed or random orientation. A good agreement is achieved between the experiment and the simulation.