Optical manipulation of photonic defect-modes in cholesteric liquid crystals induced by direct laser-lithography

• Published in: Thin solid films 2008-03, Vol.516 (9), p.2358-2362
• Main Authors: Yoshida, Hiroyuki, Lee, Chee Heng, Miura, Yusuke, Fujii, Akihiko, Ozaki, Masanori
• Format: Article
• Language: English
• Subjects: Applied sciences; Cholesteric liquid crystal; Condensed matter: structure, mechanical and thermal properties; Defect-mode; Defects in liquid crystals; Exact sciences and technology; Experimental determinations of smectic, nematic, cholesteric, and other structures; Liquid crystals; Organic polymers; Photochromic materials; Photonic band-gap material; Physicochemistry of polymers; Physics; Properties and characterization; Structure of solids and liquids; crystallography
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2007.04.093

Manipulation of photonic defect-modes in cholesteric liquid crystals (ChLCs), which are one-dimensional pseudo photonic band-gap materials have been demonstrated by an external optical field. A structural defect in which the pitch length of the ChLC in the bulk and the defect are different was introduced by inducing local polymerization in a photo-polymerizable ChLC material by a direct laser-lithography process, and infiltrating a different ChLC material as the defect medium. When an azobenzene dye-doped ChLC was infiltrated in the defect, the trans– cis isomerization of the dye upon ultraviolet (UV) exposure caused the pitch to shorten, changing the contrast in the pitch lengths at the bulk and the defect, leading to a consequent shifting of the defect-mode. The all-optical manipulation was reversible and had high reproducibility.