We have observed extraordinarily large optical nonlinearity in Methyl Red–doped nematic liquid-crystal film. Grating diffraction can be generated with an optical intensity as low as 40 µW/cm<sup>2</sup> , and a refractive-index change coefficient of more than 6 cm<sup>2</sup>/ W is obtained. The effect is attributed to formation of an optically induced dc space-charge field and to the resulting reorientation of the highly birefringent nematic director axis.
© 1998 Optical Society of America
(010.1080) Atmospheric and oceanic optics : Active or adaptive optics
(100.0100) Image processing : Image processing
(160.3710) Materials : Liquid crystals
(160.5320) Materials : Photorefractive materials
(190.0190) Nonlinear optics : Nonlinear optics
I. C. Khoo, S. Slussarenko, B. D. Guenther, Min-Yi Shih, P. Chen, and W. V. Wood, "Optically induced space-charge fields, dc voltage, and extraordinarily large nonlinearity in dye-doped nematic liquid crystals," Opt. Lett. 23, 253-255 (1998)