Fig. 4: Reversible transformation of topological patterning.
From: Harnessing acoustic topology for dynamic control of liquid crystal defects
a Simulated Gor’kov potential fields with identical excitation frequencies [fx = fy], yellow regions represent antinodes, with the distance between neighboring nodes equal to \(\sqrt{2}/2\) of the wavelength. b,c Lattice of umbilic defects with topological charge +1 located at the center of each square formed by antinodes, shown in POM images without (b) and with (c) a 530 nm phase retardation plate, scale bar 100 μm. This lattice is generated by identical frequency excitation. d Simulated Gor’kov potential fields with different excitation frequencies [fy = fx + δf], where the distance between neighboring nodes is half the wavelength. e,f POM images of a lattice of umbilic defects with topological charge +1, located at the center of each antinode square; e shows the lattice without a wave plate, and f with an inserted wave plate. This configuration is generated by different frequency excitation. g Topological analysis of the different excitation states with the basic unit length set at half the wavelength. h The radial distribution function g(r) for different excitation states, indicating the spatial distribution of defects across the two frequency excitation conditions.
