Improvement of the third order nonlinear optical properties of nematic liquid crystal under the influence of different compositional percentage of doped SWCNT and the external electric field

Abstract

In this research, the nematic liquid crystal (NLC) was doped with varying concentration (0–1 wt%) of single walled carbon nanotubes (SWCNTs) at room temperature to study the nonlinear optical (NLO) properties of E5CN7@CNT cell. The third order NLO properties such as the nonlinear susceptibility, the nonlinear refraction (NLR) and the nonlinear absorption (NLA) were determined by using Z-scan techniques. The nonlinear studies have been done using a continuous wave (CW) He: Ne laser at 632.8 nm. Doping SWCNTs to eutectic uniaxial NLC (E5CN7) enhanced the third order nonlinear susceptibility, χ(3) and consequently the nonlinearity properties of composite systems improved. It is found that at lower concentration of CNTs (c < 0.75 wt%), the third order nonlinear susceptibility are increased, but for concentration 0. 5 < c < 1 wt%, the third order nonlinear susceptibility are decreased. The negative sign of the observeLO properties of samples wed NLR index, n2 indicates that the E5CN7@CNT exhibits self-defocusing type optical nonlinearity. The two photon absorption (TPA) behavior, corresponding to negative sign NLA of samples. The reorientation of samples molecules amplifies upon the application of electric field, then nonlinearity increases.