Investigation of electrical and nonlinear optical properties of colloidal composite nematic liquid crystal

The synthesized TiO2 nanoparticles (NPs) doped to nematic liquid crystals (NLCs) with 1% wt. for both alignments (homeotropic and homogeneous). Dielectric permittivity of samples was measured by LCR meter at different temperatures. TiO2 NPs doped into NLCs show higher permittivity than pure NLCs. According to the obtained results, the permittivity of ε⊥ increases more than ε׀׀ in samples. The magnitude and temperature dependence of the refractive indices of TiO2 NPs doped into NLCs are reported. Investigated electrical behavior of the sample was studied over a wide range of frequency using a complex impedance spectroscopy (CIS) technique. The third-order nonlinear optical properties of TiO2 NPs doped into NLCs which tested by a Z-scan method with continuous wave (CW) He: Ne laser beam, are reported. The Z-scan results revealed that the TiO2 NPs in NLCs exhibit self-focusing nonlinearity and saturable absorption effect for both alignments. The results showed that NLCs doped with a small amount of TiO2 NPs can have significantly improved electro-optic properties.