Computational modelling of light propagation in textured liquid crystals based on the finite‐difference time‐domain (FDTD) method

Abstract

Light propagation through uniaxial rod-like nematic liquid crystal films containing singular (thin) and non-singular (thick) line disclinations is computed using the finite-difference timedomain method (FDTD), which is based on accurate numerical solutions to the governing Maxwell equations. The results obtained by the FDTD method are compared with classical matrix-type methods, including the aggregate model and Berreman's method. It is found that the optical signals for singular and non-singular defects predicted by the matrix methods deviate significantly from the FDTD method because director gradient effects on the plane normal to the incident light are not properly taken into account . It is also found that the FDTD optical signal for singular thin lines has a characteristic length scale associated with the wavelength of the incident light, while for non-singular thick lines the scale is associated with the defect escaped core dimensions. The FDTD method offers an accurate quantitative tool for use in new applications including liquid crystal-based biosensors and rheo-optical characterization of liquid crystalline polymers.

Finite-difference time-domain method calculation of light propagation through H-PDLC

“…The FDTD method accommodate multidimensional inhomogeneity of the dielectric tensor, it is capable of directing spherical waves, plane waves or Gaussian beams while in arbitrary incidence on material. Now it is well developed to study the light propagation in isotropic and anisotropic media and its efficiency has been proved in various light-LC problems [16][17][18]. This consolidates us in the choice of such a tool.…”

Accurate transmittance analysis of liquid crystal displays using a rational fraction approach in the time domain

“…The finite-difference time-domain (FDTD) computation [1][2][3] of Maxwell's equations has been widely used as an efficient simulation tool to successfully predict lightwave propagation within liquid crystal (LC) devices [4][5][6][7][8][9]. Here, the FDTD method can simulate the complex anisotropic LCs by considering strong scattering and diffractive effects due to the rapid LC variation as well as spatial inhomogeneties of the LC director orientation, while the commonly used matrix methods are limited by specific types of geometries in modeling anisotropic structures [10,11].…”

Tunable nano-wrinkling of chiral surfaces: Structure and diffraction optics

“…The FDTD method is established as an accurate numerical method to solve Maxwell's equations and as an efficient tool for simulation of light propagation in liquid crystals containing complex textures. 35 It has been shown that the FDTD method is capable of predicting optical responses to textured nematic liquid crystal films containing non-uniform orientation induced by variations in surface anchoring. 36 The interaction between the incident light and the nanoscale periodic structure shows bistructural color reflection through hydration and dehydration.…”