Generation of Multiple Circular Walls on a Thin Film of Nematic Liquid Crystal by Laser Scanning

TL;DR

This paper demonstrates a method to generate multiple circular walls in nematic liquid crystal films using laser scanning, revealing constant radius ratios and chiral symmetry-breaking phenomena.

Contribution

It introduces a novel laser scanning technique to create multiple circular walls in nematic liquid crystals and explains their formation through elastic energy minimization.

Findings

Constant ratios between adjacent ring radii.

Chiral symmetry-breaking in director field.

Theoretical explanation via Frank elastic free energy.

Abstract

We found that multiple circular walls (MCW) can be generated on a thin film of a nematic liquid crystal through a spiral scanning of a focused IR laser. The ratios between radii of adjacent rings of MCW were almost constant. These constant ratios can be explained theoretically by minimization of the Frank elastic free energy of nematic medium. The director field on a MCW exhibits chiral symmetry-breaking although the elastic free energies of both chiral MCWs are degenerated, i.e., the director on a MCW can rotate clockwise or counterclockwise along the radial direction.