Figure 1. Laser-generated structures formed by twist-escaped disclination clusters.

(a) POM image of a spiral structure. (b) POM image of an optically-generated phase grating composed of the finger structures. The inset shows the corresponding diffraction pattern obtained using a HeNe laser beam. (c) “Topological cat” from the cover of Ref.9 generated by steering the focused laser beam in the LC cell. (d) (e) Schematics of the director structure with a quadrupole of disclinations of positive and negative half-integer strengths (red and green filled circles, respectively) in (d) a nematic and (e) a cholesteric LC with the qudrupole of the defects running along the finger's length. (f) Experimental and (g) computer-simulated vertical 3PEF-PM cross-sections of the finger's structure in a plane orthogonal to the finger. (h) Computer-simulated director structure in the vertical cross-section of an individual finger. The director fields are visualized by use of cylinders representing rod-like molecules of the LC. “P” and “A” in (a) (b) and (c) mark crossed polarizer and analyzer in POM.