We investigated the third-order nonlinear optical properties of several donor-substituted cyanoethynylethene 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 µm, the rotational average of the third-order molecular polarizability is 53±13×10−48 m5 V−2 (3.8×10−33 esu) for the best molecule, which corresponds to 1.7×10−48 m5 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.
© 2005 Optical Society of America
(160.4330) Materials : Nonlinear optical materials
(160.4890) Materials : Organic materials
(190.0190) Nonlinear optics : Nonlinear optics
(190.4400) Nonlinear optics : Nonlinear optics, materials
(190.4710) Nonlinear optics : Optical nonlinearities in organic materials
Joshua C. May, Jin H. Lim, Ivan Biaggio, Nicolle N. P. Moonen, Tsuyoshi Michinobu, and François Diederich, "Highly efficient third-order optical nonlinearities in donor-substituted cyanoethynylethene molecules," Opt. Lett. 30, 3057-3059 (2005)