Theoretical and experimental studies of the molecular second order nonlinear optical responses of heteroaromatic compounds

We present theoretical and experimental studies of the molecular second order nonlinear optical responses of donor-acceptor substituted conjugated compounds which consist of heteroaromatic moieties in place of the traditional benzenoid moieties. Electric-field-induced second harmonic generation measurement at a fundamental wavelength of 1.907 μm demonstrated a twofold increase of the off-resonant molecular hyperpolarizability of a heteroaromatic compound compared to its benzenoid counterpart. Results of theoretical calculations based on ab initio scheme are in good agreement with the experimental results. © 1994 American Institute of Physics.