Nonlinear refractive index measurements of discotic and calamitic nematic lyotropic phases

In this work, through the Z-scan technique, we report on measurements of the nonlinear refractive index (n(2)) in discotic and calamitic nematic phases at room temperature in lyotropic mixtures of potassium laurate, decanol and D2O. This technique presents high sensitivity when compared to conventional interferometry. The nonlinear optical birefringence (Delta n(2)) of these nematic phases was also determined. The sign and absolute value of this relevant nonlinear parameter are discussed in terms of structural changes in the micellar configuration which takes place in each nematic lyotropic phase.