Optical Second Harmonic Generation in Langmuir-Blodgett Films

Abstract

Materials displaying nonlinear optical (NLO) effects are attracting increasing interest because of their potential applications in devices for processing optical information in optical communication systems^1–2. Many organic materials have been shown to possess very large nonlinearities which can be attributed to the highly polarisable π—electrons³. A large molecular hyperpolarizability, β, responsible for second-order effects can be achieved in the charge asymmetric donor-acceptor molecules. However, to achieve large bulk second-order effects it is necessary to arrange the individual molecules in a noncentrosymmetric structure in order to avoid cancellation of the individual molecular nonlinearities.