Accurate, Efficient and Rigorous Numerical Analysis of 3D H-PDLC Gratings

Abstract

This work presents recent results derived from the rigorous modelling of holographic polymer-dispersed liquid crystal (H-PDLC) gratings. More precisely, the diffractive properties of transmission gratings are the focus of this research. This work extends previous analysis performed by the authors but includes new features and approaches. More precisely, full 3D numerical modelling was carried out in all analyses. Each H-PDLC sample was generated randomly by a set of ellipsoid geometry-based LC droplets. The liquid crystal (LC) director inside each droplet was computed by the minimisation of the Frank elastic free energy as a function of the applied electric field. The analysis carried out considered the effects of Frank elastic constants K11, K22 and K33; the anchoring strength W0; and even the saddle-splay constant K24. The external electric field induced an orientation of the LC director, modifying the optical anisotropy of the optical media. This effect was analysed using the 3D split-field finite-difference time-domain (SF-FDTD) method. In order to reduce the computational costs due to a full 3D tensorial analysis, a highly optimised method for high-performance computing solutions (HPC) was developed. The influences of the anchoring and voltage on the diffraction efficiencies were investigated, showing the potential of this approach.

General application of the genetic algorithm to the estimation of the Liquid Crystal Director in PA-LC devices

“…This approach implies a complex derivation and an iterative process that must be reformulated if some term in f changes. This situation can happen if specific anchoring conditions are needed or if holographic-polymer dispersed liquid crystal (H-PDLC) elements are analysed following this procedure [6].…”

Adulterant Detection in Peppermint Oil by Means of Holographic Photopolymers Based on Composite Materials with Liquid Crystal

“…This is the expected result for an HPDLC. Therefore the peppermint oil does not change the overall process of obtaining the diffraction grating as an internal structure into the material [34][35][36].…”

Numerical modeling of H-PDLC devices for diffractive optical elements with variable properties

“…The workflow for this numerical analysis is the same that the one shown in [17]. Firstly, the H-PDLC sample is generated through a set of random LC droplets with arbitrary characteristics (considering a set of constraints) and allocated inside the grating following the input parameters provided (period, thickness, LC refractive indices, etc.).…”

“…However, in this work, lower limits are considered to be closer to non-homogeneous H-PDLC droplets configurations, thus triggering light scattering. In [17] the author extended the work previously mentioned [9] by including a full tensorial three-dimensional numerical analysis carried out using SF-FDTD and estimating the LC director through the minimisation of the total free energy [7,18]. This process takes into account the contributions of the deformation, surface and electric field [19], i.e., the solution considers the influence of K 11 , K 22 , K 33 , K 24 elastic constants, anchoring strength, and external field.…”