title: Novel pathways for enhancing nonlinearity of organics utilizing metal clusters.
abstract: We show that ultrasmall metallic nanoparticles can be combined with large second- and third-order response organic chromophores to enhance the overall third-order response of the system. This approach can be used in combination with microscopic cascading to generate exceptionally large third-order response. Intermolecular charge-transfer coupling between the molecules and the metal clusters enhances the real part of the nonlinearity at telecommunication wavelengths, while avoiding plasmonic enhancement of one- and two-photon absorption, and minimizing optical losses. The results of density functional calculations for a molecule with large second-order response, (para)nitroaniline, show that use of a gold cluster as a link between molecular entities enhances third-order nonlinearity. Varying size and shape of the metal cluster as well as the distance between the clusters and the molecules allows fine-tuning of nonlinear response over a large range of magnitudes.
authors.affiliation: Department of Theoretical Chemistry, Royal Institute of Technology, Roslagstullsbacken 15, S-106 91 Stockholm, Sweden.
authors.forename: Zilvinas
authors.initials: Z
authors.lastname: Rinkevicius
authors.forename: Jochen
authors.initials: J
authors.lastname: Autschbach
authors.forename: Alexander
authors.initials: A
authors.lastname: Baev
authors.forename: Mark
authors.initials: M
authors.lastname: Swihart
authors.forename: Hans
authors.initials: H
authors.lastname: Agren
authors.forename: Paras N
authors.initials: PN
authors.lastname: Prasad