Z-scan determination of the third-order optical nonlinearity of a triphenylmethane dye using 633 nm He–Ne laser

Abstract

The third-order nonlinear optical response of a triphenylmethane dye (Acid blue 7) was studied using the Z-scan technique with a continuous-wave He–Ne laser radiation at 633nm. The magnitude and sign of the third-order nonlinear refractive index n2 of aqueous solution of Acid blue 7 dye were determined; the negative sign indicates a self-defocusing optical nonlinearity in the sample studied. The negative nonlinear refractive index n2 and nonlinear absorption coefficient β were estimated to be −1.88×10−7cm2/W and −3.08×10−3cm/W, respectively, corresponding to Re(χ(3))=−8.35×10−6esu, and Im(χ(3))=−6.88×10−7esu. The experimental results show that Acid blue 7 dye have potential applications in nonlinear optics.