LC Physics

Session 2A: LC Physics
Monday, Feb. 13, 2017  16:10-17:45
Chair: Hak-Rin Kim, Kyungpook National University, Korea
Room: Lecture Hall III
17:00 - 17:15 Paper No.  2017-MON-S0102-O001
Myeong Ock Ko
Dynamic behavior of cholesteric liquid crystal using high-speed wavelength-swept laser

In this paper, we have investigated a dynamic behavior of the CLC structure according to the applied electric field using a high-speed wavelength-swept laser, where the structure of CLC cell is abruptly varied as soon as the applied electric field to the CLC cell has large enough. Then, the director is rearranged rapidly and the photonic bandgap is changed. In order to investigate the dynamics of a CLC structure, we fabricated a CLC cell which is prepared by mixing the nematic LC (ML-9704) and chiral dopant (S811, Merck). We have successfully measured the variation of the photonic bandgap in the CLC structure using the temporal signals, which correspond to the spectral signals of the wavelength-swept laser.

 Preview abstract
17:15 - 17:30 Paper No.  2017-MON-S0102-O002
Shinji Bono
Rotation of cholesteric droplets under UV light irradiation

We introduced azobenzene into cholesteric (Ch) liquid crystals (LCs), and we investigated rotation of Ch droplets coexisting with an isotropic phase under UV-light irradiation. Trans-isomer of azobenzene in Ch LCs absorbs UV-light and transfers to cis-isomer. Thus, UV-light intensity is expected to be weaker as thickness deeper, so that a concentration of cis-isomer spatially varies from top to bottom of cell. We found that mass flux of cis isomer along the concentration gradient drive rotation of Ch droplets.

 Preview abstract
17:30 - 17:45 Paper No.  2017-MON-S0102-O003
Hiroyuki Yoshida
Creation of defect loops in nematic liquid crystals through surface orientation control

Topological defects in liquid crystals are attractive subjects of study, as they allow for the testing of topological theories, and act as scaffolds to trap nano- and micro-sized colloidal objects. Moreover, recent studies have proven that defects not only trap mesoscopic materials, but also low-molecular-weight molecules dissolved in the host nematic liquid crystal. Considering the potential of topological defects as templates for bottom-up assembly of molecular and mesoscopic materials, the technology to create stable topological defects with complex shapes is much in need. We have previously shown that it is possible to induce topological defect lines with controlled shapes and numbers by sandwiching nematic liquid crystals between substrates with orientational easy axis distributions with singular points. However, the previous study only allowed the generation of line defects with ends anchored on one of the substrates of the cell. In this study, a design strategy is presented that allows topological defect loops floating in the bulk of the nematic liquid crystal to be generated.

 Preview abstract