Self-Organized Periodic Photonic Structure in a Nonchiral Liquid Crystal

Abstract

A hybrid-aligned cell of the smectic A liquid material 8CB gives two stable director configurations, one of which is periodic and gives strong diffraction of light. This photonic lattice director profile arises from ''frustration'' caused by conflicting constraints imposed by the boundary conditions and the constant amplitude smectic density wave. A model is proposed which accords well with the experiment results, predicting correctly the dependence of the periodicity on the cell thickness and reproducing optical polarization microscopy results.

Controlling the Self‐Assembly of Periodic Defect Patterns in Smectic Liquid Crystal Films with Electric Fields

“…By analogy with similar patterns obtained in open fi lms [ 21 ] and closed cells [ 19,38 ] we deduce that the FCDs (Figure 2 a) were nontoroidal (eccentric), with the major axis of the ellipse oriented along the anchoring direction x and the conjugated hyperbola lying in the vertical plane parallel to x . …”

“…Surface interactions that do not impose any particular in-plane alignment, such as degenerate parallel (planar) and normal (homeotropic) anchoring, produce axially symmetric defect domains known as toroidal focal conic domains (FCDs) that self-organize into close-packed hexagonal lattices. [16][17][18]25 ] On the other hand, oriented 1d arrays of straight linear domains (LDs) [12][13][14][15]33 ] and lattices of eccentric FCDs [ 19,21 ] are created at the interface between air, inducing homeotropic anchoring, and a substrate inducing unidirectional planar anchoring.…”

Competition of lattice and basis for alignment of nematic liquid crystals

“…Bistability is desirable [10][11][12][13] both for reduced power consumption and improved addressing of hi-resolution displays. Beyond displays, patterned LC systems are promising candidates as biosensors [14,15] and photonic devices [16,17].…”

Optically pumped mirrorless lasing. A Review. Part II. Lasing in photonic crystals and microcavities

“…These are twist grain-boundary phases [5], smectic Q [33] and defect patterns in smectics with the photonic structure, in particular a periodical array of focal conic domains in the hybrid aligned smectic A films [34,35]. Lyotropic chromonic LCs (LCLC), most of which are dyes, also represent promising materials for the optically pumped mirrorless lasing [36,37].…”