Large third-order optical nonlinear susceptibility in natural dye derived from Clitoria ternatea petal

Abstract

The third-order nonlinear optical response of Clitoria ternatea (CT) petal's dye in various solvents were characterized via Z-scan technique with a diode pumped solid state (DPSS) laser at 532 nm. The observations from the closed aperture z-scan showed the dye possess a self-defocusing effect with a negative nonlinear refractive index, n2 with a moderate magnitude of real part of the third-order nonlinear optical susceptibilities, Re χ(3) of the order of 10−10 esu. Open z-scan results showed that the CT dyes samples demonstrate a reverse saturable absorption (RSA) with strong two-photon absorption (TPA) coefficients, β ~ 10−3 cm/W, corresponds to large imaginary parts, Im χ(3) in the order of 10−5 esu. The highest values of n2 and β was observed in CT dye in ethanol and dimethyl sulphoxide, respectively. Not only the linear absorption spectra depends on the type of solvent used, but also the nonlinear characteristics are drastically influenced by it. On the whole, large χ(3) of the dye samples were found to be in order of 10−5 esu. Based on the measured value of nonlinear susceptibility, χ(3), the natural dye derived from CT petals can be a candidate for applications such as optical limiting and switching.