The use of mould-templated surface structures for high-quality uniform-lying-helix liquid-crystal alignment

The chiral-flexoelectrooptic effect in a Uniform Lying Helix (ULH) configuration provides a sub-millisecond in-plane rotation of the optic axis with the application of a transverse field. This enables displays with a wide viewing angle without costly in-plane-type electrodes. The salient challenge is one of alignment of the ULH, which is not topologically compatible with uniform alignment surface treatments. Here, we create a micro-grooved surface structure with features on the micron scale by using a replica-moulding technique. When the cell is assembled, the micro-grooves create channels, and using surface-energy considerations, we explain how and show experimentally that the channels align a cholesteric material in the ULH geometry with the helicoidal axis oriented parallel to the channels. The resultant alignment provides a high level of contrast between crossed polarizers and exhibits an electrooptic response with a switching time of the order of tens of microseconds.

[1]  A. E. Blatch,et al.  Effect of polymer concentration on stabilized large-tilt-angle flexoelectro-optic switching , 2006 .

[2]  Alexander Jesacher,et al.  Uniform Lying Helix Alignment on Periodic Surface Relief Structure Generated via Laser Scanning Lithography , 2011 .

[3]  Short pitch cholesteric electro-optical device stabilized by nonuniform polymer network , 2005 .

[4]  H. Yokoyama,et al.  In-plane bistable nematic liquid crystal devices based on nanoimprinted surface relief , 2007 .

[5]  S. Elston,et al.  Investigation into chiral active waveplates , 2006 .

[6]  A. E. Blatch,et al.  Structure-flexoelastic properties of bimesogenic liquid crystals. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[7]  G. Bryan-Brown,et al.  Alignment of cholesteric liquid crystals using periodic anchoring , 1999 .

[8]  J. Willmott,et al.  The effect of the molecular structure on flexoelectric coupling in the chiral nematic phase , 2001 .

[9]  Harry J. Coles,et al.  Optimized flexoelectric response in a chiral liquid-crystal phase device , 2005 .

[10]  L. Lisetski,et al.  Cholesteric liquid Crystals: Physical Properties and Molecular-Statistical Theories , 1986 .

[11]  F. Castles,et al.  Flexoelectro-optic properties of chiral nematic liquid crystals in the uniform standing helix configuration. , 2009, Physical review. E, Statistical, nonlinear, and soft matter physics.

[12]  P. Hands,et al.  Spontaneous induction of the uniform lying helix alignment in bimesogenic liquid crystals for the flexoelectro-optic effect , 2012 .

[13]  Rudquist,et al.  Linear electro-optic effect in a cholesteric liquid crystal. , 1994, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[14]  P. Cladis,et al.  The Cholesteric Domain Texture , 1972 .

[15]  H. Coles,et al.  ENHANCED FLEXOELECTRIC SWITCHING BEHAVIOUR IN THE CHIRAL NEMATIC PHASE , 2001 .

[16]  Tsung-Hsien Lin,et al.  A stable and switchable uniform lying helix structure in cholesteric liquid crystals , 2011 .

[17]  Steve J. Elston,et al.  Spontaneous and stable uniform lying helix liquid-crystal alignment , 2013 .

[18]  R. Caputo,et al.  Development of a new kind of switchable holographic grating made of liquid-crystal films separated by slices of polymeric material. , 2004, Optics letters.

[19]  H. Coles,et al.  THE FLEXOELECTRIC BEHAVIOUR OF A HYPERTWISTED CHIRAL NEMATIC LIQUID CRYSTAL , 2001 .

[20]  C. Umeton,et al.  Short pitch cholesteric electro-optical device based on periodic polymer structures , 2009 .

[21]  S. Elston,et al.  Flexoelectric switching in a zenithally bistable nematic device , 2005 .

[22]  Liquid crystal anchoring utilizing surface topological effects of self-structured dual-groove patterns , 2012 .

[23]  Patel,et al.  Flexoelectric electro-optics of a cholesteric liquid crystal. , 1987, Physical review letters.

[24]  G. Hegde,et al.  Periodic anchoring condition for alignment of a short pitch cholesteric liquid crystal in uniform lying helix texture , 2010 .