Electro-optical nonlinearity and Kerr effect engineering in SnO₂-doped nematic liquid crystal for advanced photonic...

This study reports a concentration- and temperature-dependent analysis of the Kerr effect and third-order nonlinear optical response in SnO₂ NP-ML-1102 composites (0.1-0.9 wt%). Ordinary and extraordinary refractive indices, birefringence, normalized polarizabilities, and Kerr constants were analyzed to investigate the optical and electro-optical characteristics of the host medium. Positive birefringence was maintained across the investigated temperature range for all compositions. The Kerr constant and the derived third-order susceptibility χ⁽³⁾ exhibited a clear dependence on nanoparticle loading, with the highest values observed near the nematic-isotropic transition for the 0.7 wt% composite. However, compositions outside this concentration range showed comparatively reduced nonlinear response. The pre-transitional temperature (T^*), determined from the inverse Kerr constant behavior, displayed a non-monotonic variation with nanoparticle concentration, consistent with phenomenological expectations for fluctuation-mediated electro-optical effects. The results demonstrate that nanoparticle incorporation provides a practical route for adjusting nonlinear electro-optical behavior in nematic liquid crystal systems.