Large Angle Forward Diffraction by Chiral Liquid Crystal Gratings with Inclined Helical Axis

A layer of chiral liquid crystal (CLC) with a photonic bandgap in the visible range has excellent reflective properties. Recently, two director configurations have been proposed in the literature for CLC between two substrates with periodic photo-alignment: one with the director parallel to the subs...

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Bibliographic Details
Published in:Crystals (Basel) 2020-09, Vol.10 (9), p.807
Main Authors: Stebryte, Migle, Nys, Inge, Ussembayev, Yera Ye, Beeckman, Jeroen, Neyts, Kristiaan
Format: Article
Language:English
Subjects:
chiral liquid crytals
diffraction
flat optics
full reflection band
photonic band gap
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Summary:A layer of chiral liquid crystal (CLC) with a photonic bandgap in the visible range has excellent reflective properties. Recently, two director configurations have been proposed in the literature for CLC between two substrates with periodic photo-alignment: one with the director parallel to the substrates and one with the director in the bulk parallel to the tilted plane. The transmission experiments under large angles of incidence (AOI) presented in this work prove that, in the bulk, the director does not remain parallel with the substrates. Because of the inclined helical axis, the full reflection band can be observed at a smaller AOI than in planar CLC. For sufficiently large AOI, the reflection of diffracted light is prohibited by total internal reflection and efficient diffraction occurs in the forward direction.
ISSN:2073-4352
2073-4352
DOI:10.3390/cryst10090807