Highly efficient third-order optical nonlinearities in donor-substituted cyanoethynylethene molecules

摘要

We investigated the third-order nonlinear optical properties of several donor-substituted cyanoethy-nylethene molecules in the zero-frequency limit. We observed nonlinearities that are extraordinarily large relative to the small molecular mass of these molecules and that are within a factor of 50 from the fundamental limit. At a wavelength of 1.5 (mu)m, the rotational average of the third-order molecular polarizability is 53+-13 X 10~(-48) m~(5) V~(-2) (3.8 X 10~(-33) esu) for the best molecule, which corresponds to 1.7 X 10~(-48) m~(5) V~(-2) per delocalized electron. The high nonlinear efficiency of these molecules is due to the compact two-dimensional conjugated system and the effective donor-acceptor substitution patterns.