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Proceedings Paper

Mesoscale lattices and temporal multiplexing in liquid crystal/polymer dispersions
Author(s): Matthew E. Sousa; Jun Qi; Michael J. Escuti; Gregory P. Crawford
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Paper Abstract

We demonstrate multi-beam holographic lithography and temporal multiplexing techniques to create complex two- and three-dimensional structures in holographic polymer-dispersed liquid crystal (H-PDLC) materials. H-PDLCs are a variant of PDLCs formed under holographic conditions. The holographic image is typically a two-beam interference pattern, resulting in an array of liquid crystal (LC) droplets and solid polymer planes that act as a Bragg grating. Applying an external electric field can reversibly erase the resulting refractive index modulation. Using multi-beam holographic lithography, two-dimensional square lattices and three-dimensional FCC lattices have been created. The structures of the created lattices have been confirmed using a scanning electron microscope. We demonstrate the switchability of the lattices and tunability of the photonic bandgaps upon application of an electric field. Instead of simultaneously exposing a sample to multiple laser beams, we have developed a technique for creating complex structures by time-sequentially exposing the sample with multiple holographic configurations. By time-sequentially exposing the sample, two switchable reflection gratings are formed in a single film. The reflectance of the resulting gratings is well controlled by the individual exposure time. The optical performance can be modeled using a 2x2 matrix method based on the reaction diffusion equation.

Paper Details

Date Published: 5 January 2004
PDF: 9 pages
Proc. SPIE 5213, Liquid Crystals VII, (5 January 2004);
Show Author Affiliations
Matthew E. Sousa, Brown Univ. (United States)
Jun Qi, Brown Univ. (United States)
Michael J. Escuti, Brown Univ. (United States)
Gregory P. Crawford, Brown Univ. (United States)

Published in SPIE Proceedings Vol. 5213:
Liquid Crystals VII
Iam-Choon Khoo, Editor(s)

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