Single-beam Z-scan measurement of the third-order optical nonlinearities of triarylmethane dyes

Abstract

Solid-state dye-doped polymers are an attractive alternative to the conventional liquid-dye solutions. The search for new materials which have potential application in optoelectronic devices has lead us to probe the organic dyes. The solid state being a better medium when compared to a liquid medium has lead to the incorporation of dyes in the polymer matrix. The study of nonlinear characteristics of dyes in polymeric media is essential for developing such potential application devices. In this paper, the third-order nonlinear optical properties of three dyes from the Triarylmethane family were measured in 1-Butanol and in dye-doped polymer films by the Z-scan technique using a cw diode-pumped Nd:YAG laser at 532 nm. The Z-scan technique has also been used to present the observation of a nonlinear refractive index resulting from the photochromism of one of the dyes. These materials exhibit a large negative optical nonlinearity resulting due to the thermal effect. The relative contributions from the nonlinear absorption (NLA) and nonlinear refraction (NLR) are dependent on the chemical structure and linear absorption of the dyes. The dyes exhibited a nonlinear refractive coefficient n ₂, a nonlinear absorption coefficient β, and susceptibility x⁽³⁾ on the order of 10⁻⁸ cm²/W, 10⁻⁴ cm/W, and 10⁻⁶ esu, respectively, in both liquid and solid media. The results show that these dyes have potential applications in nonlinear optics.