NEW NONDIPOLAR STRUCTURES WITH SIGNIFICANT QUADRATIC HYPERPOLARIZABILITIES

'Octupolar' molecules are of particular interest in the field of nonli near optics due to their potentially large quadratic nonlinearities. W ithin this framework, we have designed organic chromophores of tetrahe dral symmetry and investigated their quadratic nonlinearities by perfo rming harmonic light scattering (HLS) experiments in solutions. Issues related to the molecular engineering of the nonlinearity-transparency trade-off have been addressed. As a result, molecules combining signi ficant quadratic hyperpolarizabilities and excellent transparency have been identified. (C) 1998 Elsevier Science B.V.