The effect of external applied fields on the third order nonlinear susceptibility and two-photon absorption cross-section of E5CN7@Fe3O4-CNT

The third order nonlinear optical properties and two-photon absorption(TPA) cross-section of nematic liquid crystals (NLCs) (E-5CN7) doped with Fe3O4 nanoparticles, single wall carbon nanotubes (SWCNTs) and Fe3O4-CNTs were investigated at 632.8 nm. For this aim, the low power single beam was used in Z-scan technique. The study was performed with two different concentrations of dopant with and without the electric field (15 Volt) and magnetic field (0.5 Tesla). The functionalization of SWCNTs with Fe3O4 diminishes the CNT aggregation while the third order nonlinear susceptibility and TPA cross-section are increased. The results show that the best concentration and dopant in E-5CN7 without any applying fields is 1% Fe3O4-CNT. After applying electric and magnetic fields and compare the results, the E-5CN7@1% Fe3O4-CNT under electric field exhibits the largest nonlinear responses among all the samples. The direction of external fields with respect to the director axis (n) over right arrow and then the type of initial alignment are crucial factors for changing the nonlinearity parameters. Furthermore, these results show that E-5CN7@1% Fe3O4-CNT may be the promising candidate for the magneto-optical devices.