Citation
Menéndez-Valdés Álvarez, Pedro and Martín Pereda, José Antonio
(1987).
New non-reorientational optical nonlinear effect in MBBA.
"Molecular Crystals and Liquid Crystals", v. 149
(n. 1);
pp. 303-316.
ISSN 1542-1406.
Abstract
A new effect producing self-focusing of light in a nematic MBBA film is reported. This effect produces a static diffraction pattern composed of circular rings which is
different from the ones arising from self-focusing previously reported. The influence of the cell thickness, the optical intensity, and the wavelength is studied. Once the nematic is distorted by a láser beam, the effect produced in other light beam passing through the modified región is independent of its polarization. This isotropic behavior shows that a molecular reorientation has not been produced. The origin of this effect seems to be the same of that of the effect which produces a randomly oscillating
diffraction pattern previously reported by our group. Some possible causes such as thermal indexing, convective instabilities and self-induced transparency are discussed.