Third-harmonic generation performance of organic polymer films doped with triphenylmethane derivative dyes

We report on third-order nonlinear properties of triphenylmethane derivative dyes by measuring third-harmonic generation (THG) for fundamental wavelengths within the range 1100–1800 nm. Our studies show that the triphenylmethane dyes Crystal Violet and Ethyl Violet, with a multidirectional charge transfer in their three-fold symmetry structure (octupolar dimensionality), exhibit a third-order nonlinear susceptibility of the order χ(3) ∼ 10−12 esu when are used as dopants in polymer films. These films, with low residual absorption and anomalous refractive index dispersion for harmonic wavelengths, exhibit efficient THG as a bulk effect. The films are good candidates for ultra-fast optical correlators.