Surface-mediated alignment of nematic liquid crystals with polarized laser light

Abstract

THE control of molecular alignment in liquid-crystal phases at macroscopic scales has been investigated extensively because of its importance in optical or optoelectronic applications, such as liquid-crystal displays¹. It is well established that liquid crystals can be aligned by an applied electric field, a magnetic field, a shear-flow field, mechanical grooving of the substrate surface or stretching of liquid-crystal polymer thin films^2,3. Here we report a new mechanism for liquid-crystal alignment that uses polarized laser light. We find that nematic liquid crystals in an illuminated region become oriented perpendicular to the direction of the electric-field polarization of the laser and remain aligned in the absence of the laser radiation. The liquid crystals can be reoriented again by subsequent illumination. This technique might have applications for large-area displays, optical memories, binary optics, adaptive optics and molecular micro-assembly.