Light–matter interaction induces a single positive vortex with swirling arms

Abstract

Homeotropic nematic liquid crystal cells with a photosensitive wall and negative dielectric anisotropy exhibit, under the influence of local illumination, stable vortexes with swirling arms that are trapped at the illuminated area. Close to the Fréedericksz transition an amplitude equation is derived, which allows us to understand the origin of the induced vortex and the competition between the illuminating profile and the elastic anisotropy generating the swirling of the arms.

Tunable High-Resolution Macroscopic Self-Engineered Geometric Phase Optical Elements

“…1 and 4. This implies an effective optical axis orientation angle of the form ψ(r, φ) = φ + ϕ(r) where the nonzero swirl function ϕ(r) is a generic consequence of the elastic anisotropy of the liquid crystal, as already discussed in the particular case of liquid crystal light valves [24]. Noteworthy, the swirl only imparts smooth changes to the output wavefront curvature via an pure-phase amplitude term exp[2iσϕ(r)], which therefore let the optical vortex generation process unaltered.…”

Optical vortex induction via light–matter interaction in liquid-crystal media

“…The radial symmetry of the voltage drop will give rise to a transverse component of the electric field, also with the same radial profile. This biases the system, making the nematic director follow the same symmetry while reorienting, and giving birth to a single singularity in the texture of the nematic layer [45,46,72].…”

Self-induced liquid crystal q-plate by photoelectric interface activation

“…4(d) where the map of the in-plane director orientation angle, ψ, is displayed. As discussed in previous works, the swirled structure of the umbilic (whose handedness is random) is inherent to the elastic anisotropy of nematic liquid crystals 24,26 . Self-induced optical vortex generation itself is illustrated in Figs.…”