Experiments On Ring-Shaped Solitons In Nematic Liquid Crystals

Abstract

Experiments on ring-shaped propagating single solitons in nematic liquid crystals are reported. These solutions with constant velocities and widths are generated by pressure gradients in the radial direction in homeotropic nematic disc cells. The pressure at the rim of the cell is maintained at atmospheric pressure while that at the center is varied. In suitable pressure gradient regimes these solitons appear as dark rings under transmitted parallel white light passing vertically through two crossed polarizers sandwiching the liquid crystal cell. These results are contrasted with those observed when the pressure at the rim is varied (in which both dark and white rings propagating towards the center are generated).

Key Words:

• liquid crystals
• solitons
• nematics
• two-dimensional
• solitary wave
• pressure gradients