Cubic optical nonlinearities with octupolar molecules at telecommunication wavelengths

Abstract

Here we report on the cubic nonlinear optical properties of octupolar organic molecules. A series of three compounds that were of triphenylmethane derivatives and one boroxine derivative were characterized, in solid state, at infrared wavelengths comprising telecommunication bands \mbox{(900 - 1600 nm).} At these wavelengths, for which there is practically an absence of reports about cubic nonlinearities in octupolar compounds, we measured third-order susceptibilities $\chi^{(3)}$ of the order of $10^{-12}$ esu, the latter partially enhanced by multiphoton resonances. As the molecules studied were prototypes of octupolar systems, our results correlate the magnitude of the observed nonlinearities with the molecular structure, thus providing helpful information for the design of new molecules with improved nonlinearities. On the other hand, we discuss how polymer films functionalized with these molecules can be useful for applications involving the conversion of optical frequencies. Such films produce frequency-converted signals sensitive enough that they can be employed in ultra-fast optical correlators.