Extended Data Fig. 1: Principles of photo-patterning of LC vortices.
From: Topological steering of light by nematic vortices and analogy to cosmic strings
a, Optical response of azobenzene dye molecules to linearly polarized blue light, with the dye molecular structure shown above. When illuminated by the blue light, randomly oriented rodlike dye molecules collectively re-align to point orthogonally to the excitation light’s polarization direction. b, Schematic setup of a custom-built photo-patterning system. The photo-patterning is based on a microdisplay used to project a computer-controlled blue-light pattern that is relayed by three lenses, linearly polarized by an inserted half-wave plate and a polarizer, and then projected to the back aperture of an objective, which focuses the pattern on the azobenzene dye layers. The pattern size is defined by the magnification of the objective. c, Vortices and their arrays are generated via sequential illuminations of patterns corresponding to narrow angular sectors of azimuthal orientations of dye molecules, synchronized with the corresponding control of the linear polarization (double white arrows) and its azimuthal orientation angle (Φp) to define dye molecule orientations at surfaces and, thus, define boundary conditions for n(r).
