We investigate a new ultrahighly sensitive nonlinear optical response in pure nematic liquid crystals composed of rodlike molecules characterized by conjugated acetylene groups. Under the combined application of low-intensity optical waves and dc electrical fields, a photorefractivelike grating formation has been found in degenerate four-wave mixing experiments. Polarization-dependent pump–probe experiments reveal the underlying orientational effect of a space-charge field. The photorefractive-like origin of the gratings was proved by two beam-coupling experiments in which a refractive-index grating was phase shifted by π/2 with respect to the interference grating. The huge optical nonlinearity found in such materials makes them promising for future applications in all-optical image processing and adaptive optics.
© 2001 Optical Society of America
(160.2900) Materials : Optical storage materials
(160.3710) Materials : Liquid crystals
(160.5320) Materials : Photorefractive materials
(190.4400) Nonlinear optics : Nonlinear optics, materials
(190.5330) Nonlinear optics : Photorefractive optics
P. Pagliusi, R. Macdonald, S. Busch, G. Cipparrone, and M. Kreuzer, "Nonlocal dynamic gratings and energy transfer by optical two-beam coupling in a nematic liquid crystal owing to highly sensitive photoelectric reorientation," J. Opt. Soc. Am. B 18, 1632-1638 (2001)