Quasi-phase-matched frequency conversion in chiral structures

Summary form only given. The second-order susceptibility associated with chirality has different sign for the two enantiomers of a chiral material. We demonstrate quasi-phase-matched second harmonic generation in Langmuir-Blodgett films of an aggregated chiral helicenebisquinone. Our results provide the basis for new concepts for nonlinear devices where chirality, instead of polar order, gives rise to the second-order nonlinear response and phase matching. Molecular control of the film thickness allowed us also to demonstrate, for the first time, lowest-order quasi phase matching in the reflected direction, where the thickness of each stack is one coherence length and not its multiple.