Optical generation of inversion walls in nematic liquid crystals

An approach to generate inversion walls in nematic liquid crystals using optical reorientation is described. Planar cells with small pretilt are exposed to an oblique laser beam, which reverses the director tilt angle within the irradiated area. During the electric Freedericksz transition an inversion wall surrounding the laser spot is formed. A theoretical relation is provided for the critical laser intensity necessary to produce an inversion wall. Experimental results in a dye-doped nematic are in satisfactory agreement with the theory.