Sub-wavelength modulation of ?⁽²⁾ optical nonlinearity in organic thin films.

ABSTRACT: Modulating the second-order nonlinear optical susceptibility (?⁽²⁾) of materials at the nanoscale represents an ongoing technological challenge for a variety of integrated frequency conversion and nonlinear nanophotonic applications. Here we exploit the large hyperpolarizability of intermolecular charge transfer states, naturally aligned at an organic semiconductor donor-acceptor (DA) interface, as a means to control the magnitude and sign of ?⁽²⁾ at the nanoscale. Focusing initially on a single pentacene-C₆₀ DA interface, we confirm that the charge transfer transition is strongly aligned orthogonal to the heterojunction and find that it is responsible for a large interfacial nonlinearity probed via second harmonic generation that is sufficient to achieve d₃₃>10?pm?V^-1, when incorporated in a non-centrosymmetric DA multilayer stack. Using grating-shadowed oblique-angle deposition to laterally structure the DA interface distribution in such multilayers subsequently enables the demonstration of a ?⁽²⁾ grating with 280?nm periodicity, which is the shortest reported to date.

SUBMITTER: Yan Y 

PROVIDER: S-EPMC5290150 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature